Sharks of Onslow County

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Following the Warm Water: Manatees in Onslow County

At first, it may look like a series of smooth rings spreading across the water.

Then bubbles rise. A dark shape moves beneath them. A broad back reaches the surface, followed by a rounded nose taking a quick breath before disappearing again.

Along the docks, channels, and marsh-lined sounds of Onslow County, we are used to watching for dolphins, sea turtles, rays, and the passing shadows of large fish. A manatee belongs to a different picture—one usually associated with Florida’s clear springs, mangrove rivers, and groups gathered in the warm water near power plants during winter.

Yet manatees have been appearing around Topsail Island, Surf City, and other parts of the North Carolina coast during the warmer months. In July 2024, drone footage captured several together in Topsail Beach Sound. By the following summer, the University of North Carolina Wilmington’s Marine Mammal Stranding Program reported receiving more than 100 manatee sightings from across North Carolina since 2024 (Bergin, 2024; UNCW, 2026; WECT/6, 2025).

That does not necessarily mean more than 100 different manatees visited our coast. The same animal may be seen several times as it moves from one sound or waterway to another. More people also have phones ready to photograph an animal that might once have surfaced briefly and disappeared without ever being reported.

Even so, the growing number of sightings gives us reason to look more closely.

A manatee in Onslow County may still be unexpected. It is not necessarily lost.

Farther North, but Not Entirely Out of Place

The manatees seen here are Florida manatees (Trichechus manatus latirostris), a subspecies of the West Indian manatee (Trichechus manatus) (Reep & Bonde, 2021).

Florida remains the center of their range in the United States, particularly during winter. Once the water warms in spring, however, some begin traveling.

They move into rivers, bays, estuaries, and coastal waters along the southeastern United States. Some remain within Florida. Others follow the Atlantic coast through Georgia and the Carolinas. A few have traveled as far north as Chesapeake Bay, New England, and beyond (Cummings, 2014; Deutsch et al., 2003; Rathbun et al., 1981).

Florida remains the center of the manatee’s U.S. range, but during warmer months some individuals travel north along the Atlantic coast into Georgia, the Carolinas, Virginia, and beyond. | Image credit: Manatee Migration and Facts

North Carolina manatee sightings are therefore not new. Records of animals north of Florida go back for generations (Cummings, 2014; Gunter, 1941; Irvine & Campbell, 1978; Rathbun et al., 1981). What may be changing is how frequently they are being seen and how much of their movement we are now able to record.

A growing Florida population may mean more animals are reaching the outer edges of their range. Warmer coastal water may allow them to travel farther north or remain here longer. Better reporting may also be filling gaps in a migration that was already happening but was easier to miss (Cloyed et al., 2025; Laist, 2019).

One sighting cannot tell us which explanation is responsible. A collection of sightings can begin to show a pattern.

Each report adds a location and a date. Over time, those points may reveal when manatees reach North Carolina, whether they return to the same places, how long they remain, and whether mothers eventually bring calves along routes they have traveled before.

A Coast Reached by Memory

Manatees do not look like long-distance travelers.

They usually move with slow strokes of a broad, paddle-shaped tail. They may appear to drift through a canal or graze without any particular destination. Their normal swimming pace is only a few miles per hour, although they can move much faster in a short burst when startled.

A slow pace does not prevent a long journey.

A manatee traveling north does not need to swim hundreds of miles without stopping. It can move for part of the day, rest, feed, explore a side creek, and then continue. Some migrations are fairly direct. Others stretch over weeks or months as the animal pauses along the route.

The path is not as simple as keeping the beach on one side and open water on the other.

A manatee traveling along the Atlantic coast must pass through inlets, move around shoals, cross open stretches of water, and enter branching networks of rivers, sounds, and tidal creeks. Along the way, it must find water deep enough to travel, warm enough to enter, and productive enough to make stopping worthwhile.

Many manatees return to familiar summer and winter habitats year after year. They can remember travel corridors, feeding areas, freshwater sources, and the warm-water refuges that become essential once winter arrives (Deutsch et al., 2003; Reep & Bonde, 2021).

That ability was once easy to underestimate because a manatee’s brain looks different from the deeply folded brains of dolphins, primates, and elephants. Behavioral research has since shown that manatees can learn visual and sound-based tasks, remember what they have learned, and solve some discrimination problems at levels comparable with animals better known for their intelligence, including dolphins and elephants. Their intelligence is not simply a slower version of a dolphin’s. It is shaped around the problems a manatee must solve: locating food, reading water movement, recognizing useful habitat, and finding its way through a large and changing network of waterways (Cook et al., 2025; Reep & Bonde, 2021).

They also experience that watery landscape through more than sight.

The coarse hairs around a manatee’s face are called vibrissae—the same word used for a cat’s whiskers. Manatees also have smaller sensory hairs spread across the rest of their bodies. Each hair can respond to touch and movement in the surrounding water (Reep et al., 2001, 2002).

Around the mouth, the stiffest hairs help examine, grasp, and pull vegetation. Across the body, the finer hairs may help the animal detect water currents and nearby movement, giving it information about surroundings that may be difficult to see in cloudy water. It is less like having fur and more like being covered in a field of small underwater sensors (Reep et al., 2001, 2002).

The vibrissae do not hold a map of the coast. They help supply some of the information from which that map can be learned.

A familiar current, bottom texture, channel, or opening between shorelines may become one part of the larger set of clues a manatee uses as it moves. Sight, sound, touch, water temperature, and memory work together rather than as separate navigation systems.

Some of that map is learned early.

A calf remains beside its mother through its first year and sometimes longer. During that time, it follows her between feeding grounds, resting places, travel corridors, and winter refuges. The calf is not only being led from one place to another. It is learning where those places are (Deutsch et al., 2003; Reep & Bonde, 2021).

If a female repeatedly travels north and later brings a calf with her, a North Carolina sound could become part of another manatee’s remembered landscape.

That does not mean every animal seen here learned the route from its mother. Manatees also explore, and individuals do not all follow the same migration. But the animal rising beside a local dock may not have arrived here by accident.

It may be returning to a place where it previously found the right combination of water, food, and shelter.

An Animal Guided by Temperature

A manatee may weigh more than half a ton, but its large body does not protect it from cold water as well as we might expect.

Unlike whales and seals, manatees do not carry a thick layer of insulating blubber. Much of their rounded shape comes from an enormous digestive system needed to break down the plants they eat (Reep & Bonde, 2021).

When water remains below about 68°F, or 20°C, they begin losing body heat faster than they can replace it. Prolonged exposure can cause cold stress, damage internal organs, weaken the immune system, and eventually kill the animal (Bossart et al., 2003; Laist & Reynolds, 2005; Reep & Bonde, 2021).

That lower temperature limit shapes their annual movement.

During winter, Florida manatees gather around places where the water remains reliably warm. Some use natural springs that stay near the same temperature throughout the year. Others depend on warm water released near power plants. These refuges allow them to survive cold periods, but they do not always provide enough vegetation for the animals to remain there throughout the year (Flamm et al., 2012; Laist & Reynolds, 2005).

When spring warms the rivers and coast, the manatees spread out again.

They are generally comfortable in water from about 70°F to 86℉, or roughly 21–30°C. During summer, some shallow Florida bays and lagoons may reach the upper 80s or low 90s—approximately 28–33°C—while coastal waters farther north finally rise above the lower limit manatees need (Cloyed et al., 2025; Reep & Bonde, 2021).

Florida manatees are grouped into four regional populations, each connected to a network of warm-water refuges that become essential when winter water temperatures fall. | Image credit: Laist et al., 2012

That helps explain the seasonal movement, although it does not prove that animals are leaving Florida simply because it has become too hot. Manatees already live in warm tropical and subtropical environments, and individual animals respond to more than temperature alone.

But temperature does open and close the route.

As the Atlantic coast warms through spring, areas that were dangerous in February become usable by May or June. A manatee can move north through a widening corridor of suitable water, stopping where it finds food, freshwater, quiet resting places, and channels it can safely navigate.

Warmer conditions may also keep that corridor open longer than it once did. Recent models suggest that future changes in temperature and habitat could alter where manatees occur within the continental United States. For now, however, sightings alone cannot tell us how much of the increase comes from changing water temperatures, population recovery, improved reporting, or individual animals exploring beyond familiar areas (Cloyed et al., 2025; Laist, 2019).

They tell us the animals are here.

Understanding why takes a much longer record.

What They Find in Onslow County

Warm water makes the journey possible.

Food gives a manatee a reason to remain.

Manatees are plant eaters. In coastal and estuarine water, they graze on seagrasses, algae, and other aquatic vegetation. Their divided upper lip works almost like two short fingers, grasping and pulling plants into the mouth. Their front flippers can help guide the vegetation as they feed (Reep & Bonde, 2021).

An adult manatee may spend several hours grazing each day. Finding a calm creek is therefore not enough if the bottom offers little to eat. So, manatees explore to find the best combination of resources.

Onslow County’s sounds, tidal creeks, river mouths, and sheltered shorelines can provide many of the pieces a visiting manatee needs. Shallow water allows underwater grasses and algae to grow. Marsh edges offer some protection from larger waves. Inlets and deeper channels connect one feeding area to another.

Much of this habitat is easy to overlook because its most important part lies below the surface.

Submerged aquatic vegetation—or SAV—is the underwater grass growing across parts of our sounds and estuaries. These grass beds are already important to the animals that live here.

Juvenile fish hide among the blades (Orth et al., 2006). Blue crabs, shrimp, snails, and other small animals feed and shelter there. The plants slow the water enough for suspended sediment to settle, hold parts of the bottom in place, release oxygen, and absorb nutrients that might otherwise feed large algae blooms (Heck et al., 2003; Orth et al., 2006).

Clearer water then allows more sunlight to reach the bottom, which helps more grass grow.

It is a habitat that helps maintain the conditions it needs.

To a visiting manatee, the same grass may also be food.

A few summer visitors are unlikely to graze enough to remake Onslow County’s grass beds. In Florida, however, large groups of manatees can remove substantial amounts of vegetation from places they use heavily. If North Carolina becomes a regular summer destination for more animals, researchers will eventually need to understand both sides of that relationship: whether our grass beds can support repeated grazing and whether the grazing changes the beds themselves.

What Changes What They Find Here

For now, the larger concern may be whether those feeding grounds remain available at all.

Underwater grass needs light. When runoff, algae, boat wakes, or disturbed sediment make the water cloudy, less sunlight reaches the bottom. The plants may thin even though the surface of the sound looks much as it did before (Burkholder et al., 2007; Sagerman et al., 2019).

Some changes happen directly within the grass beds. Boat propellers can cut trenches through shallow vegetation. Docks shade the bottom. Development adds more hard surfaces that send runoff toward the water instead of allowing it to soak into the ground. Each change may seem small when viewed from a single property, dock, or channel. Across an estuary, those changes begin to alter how much clear, shallow habitat remains (Burdick & Short, 1999; Sagerman et al., 2019).

Other changes begin farther away but still reach the same habitat.

Beach nourishment can affect this connected system, but the effects depend greatly on where sand is removed, where it is placed, and how the project is carried out. Sand borrowed from the nearshore bottom removes or alters habitat at the borrow site. Sediment escaping into nearby water may temporarily increase cloudiness, and misplaced sand can bury submerged plants or other bottom communities (Peterson & Bishop, 2005).

That does not make every nourishment project equally harmful. Beach nourishment can protect oceanfront infrastructure and restore parts of a storm-damaged beach. The ecological question is not simply whether sand is moved. It is what habitat occupies the borrow and placement areas, how closely the new sediment matches the original sand, how much enters surrounding water, and whether sensitive areas can be avoided (Peterson & Bishop, 2005).

The recommended draft Surf City beach nourishment plan (6/6/2024) identifies offshore borrow areas where sand would be removed before being placed along the beach. Each borrow site is also part of the nearshore habitat connected to the island, inlets, and sounds behind it. | Image credit: USACE

The ocean side of a barrier island and the sound behind it may look like separate shorelines, but they belong to the same moving island.

Barrier islands naturally respond to waves, storms, rising water, and shifting inlets by changing shape and gradually moving. Sand is carried along the beach, pushed over the island during storms, and moved through inlets into the sounds behind it. Those movements help rebuild beaches, create shoals, and allow marshes and shallow-water habitats to form in new places as older ones erode (FitzGerald et al., 2008; Nienhuis & Lorenzo-Trueba, 2019).

Those shallow sound-side habitats are part of what a traveling manatee encounters. The grass beds, marsh edges, shoals, and deeper channels behind the island are shaped partly by sand moving across and around the barrier island itself.

Hard structures are designed to stop part of that movement.

A seawall, revetment, terminal groin, or other hardened structure may protect a building, road, or inlet beside it. But the barrier island does not stop moving simply because one section has been fixed in place. Waves continue carrying sand. Storm water still crosses the island. Inlets and neighboring shorelines continue adjusting around the structure (Dugan et al., 2017; FitzGerald et al., 2008).

When sand can no longer move naturally through one part of the system, erosion may increase nearby or the beach in front of the structure may narrow (Dugan et al., 2017; Kraus & McDougal, 1996). Changes on the ocean side can also affect the amount and path of sediment reaching the inlet, shoals, marsh edges, and shallow sound-side habitat behind the island (FitzGerald et al., 2008; Hein et al., 2019).

That is why the current North Carolina debate over hard structures is larger than whether one structure protects one stretch of property. The question is also what happens to the connected habitats behind the barrier island when a moving shoreline is held in one place.

The same principle applies along the sounds.

A bulkhead may protect a particular property line, but it replaces the gradual meeting of land and water with a wall. Waves strike that wall and may scour sediment from its base or neighboring shoreline. Marsh plants lose the gently sloping ground they need, and as water levels rise, the marsh cannot move inland through a structure.

Living shorelines take a different approach. Marsh plants, oyster shell, low sills, and other natural materials soften waves while keeping more of the gradual connection between land and water. They do not fit every location, but where conditions allow them, they can protect a shoreline without removing all of the habitat at its edge (Gittman et al., 2015, 2016).

Marsh edges, shallow bottoms, shell beds, and underwater grasses do not function as separate pieces. They are part of the bigger ecosystem.

Young shrimp and fish shelter in the grass. Larger fish feed on them. Birds, dolphins, sharks, and people then depend on animals produced within those nursery areas. Remove enough bottom vegetation and the effect does not stop with the grass (Heck et al., 2003; Seitz et al., 2013).

It moves through the food web.

The manatee is not part of that food chain in quite the same way because it eats the plants directly. But its dependence on those grasses places it within the same connected system. Habitat that feeds a manatee also shelters prey for red drum, flounder, speckled trout, blue crabs, and many of the animals people come here hoping to catch or see (Heck et al., 2003; Orth et al., 2006).

A manatee allows us to view that familiar landscape from another direction.

The animal may be large enough to notice from a pier, but it depends on plants that can vanish from the bottom without most people realizing anything has changed. A sound may still look open and inviting from the surface while offering less food and shelter beneath it.

Dredging More Than a Channel

Dredging is part of living along a coast built from moving sand.

Inlets shoal. Channels fill. Boats need safe routes between docks, sounds, and the ocean. Removing sediment can reopen water that has become too shallow to navigate, and a maintained channel may also provide a deeper travel route for a manatee.

But dredging does more than deepen a line across a map.

Where dredging passes through shallow habitat, it may remove submerged grass, soft-bottom communities, shell material, worms, clams, and the small animals living within the sediment. Deepening shallow water may also change how light reaches the bottom and how water moves through the surrounding area (Erftemeijer & Lewis, 2006; Newell et al., 1998).

A patch of grass is not simply removed from the manatee’s menu.

The plants, shell material, and soft sediment form habitat for organisms living both on and beneath the bottom. When that bottom is removed, the community living within it is removed as well. How quickly it returns depends on the type of sediment, the organisms that lived there, surrounding currents, and whether the area is disturbed again before it can recover (Newell et al., 1998).

Sediment suspended during the work may spread beyond the channel itself. As it settles, it can cover nearby plants or shell bottom. While it remains in the water, it blocks light and makes it harder for underwater vegetation to grow. Suspended sediment can also affect fish and shellfish, although the severity depends on how much sediment is present and how long the organisms are exposed to it (Erftemeijer & Lewis, 2006; Wilber & Clarke, 2001).

The answer is not that dredging should never occur. Boats, commercial fisheries, emergency access, and coastal communities all depend on navigable waterways.

The important part is recognizing what lies beneath the proposed route before the bottom is removed—and understanding that a channel cannot be considered separately from the grass beds, marshes, shellfish areas, and shallow nurseries around it.

The same is true when we look at the coast as a whole.

Dredging, bottom trawling, beach nourishment, hardened shorelines, docks, and development are often considered one project or one management decision at a time. The habitat experiences all of them together.

A grass bed already weakened by cloudy water may then be crossed by propellers. A bottom community disturbed by dredging may have less time to recover if the same area is repeatedly trawled or altered by another project. A nursery area may also receive less sediment because of a structure farther along the barrier island.

One action may cause a temporary or limited change. Several disturbances layered across the same connected system can create a larger or longer-lasting effect than any one of them would create alone (Korpinen & Andersen, 2016; Stockbridge et al., 2020).

Protecting the coast therefore requires more than reducing the effects of each individual project. It requires looking at where those projects overlap, what has already changed, and how much working habitat remains before the next solution is added.

The habitat that draws a manatee here is not simply warm water or one patch of grass.

It is the connection among those places: enough food to feed, deeper water to travel, quieter areas to rest, and a route that remains open when it is time to move south.

When Summer Habitat Becomes a Winter Trap

The same waterway that supports a manatee in August may become dangerous by late fall.

Manatees can detect small differences in water temperature and use those differences to locate warmer areas. That sensitivity helps them follow changing conditions, but it cannot create a warm refuge where none exists.

Florida contains springs and heated outfalls that remain warm during winter. Onslow County does not offer the same dependable network.

A deep canal may appear sheltered from wind and waves. Its depth alone cannot keep the water above the temperature a manatee needs.

Because manatees have a relatively slow metabolism and little insulating fat, prolonged cold affects more than their comfort. Digestion begins to slow, appetite falls, and the animal may rapidly lose weight even though its body still needs energy to stay warm. Pale or white areas and open sores may develop across the skin, particularly around the face, flippers, and tail (Bossart et al., 2003).

Cold stress also weakens the immune system. A manatee that survives the first loss of body heat may then become vulnerable to pneumonia, bacterial infections, and a wider breakdown of normal body functions. What begins as exposure to water only a few degrees too cold can become a chain of problems the animal can no longer reverse on its own (Bossart et al., 2003).

The first documented live rescue of a manatee in North Carolina showed how quickly seasonal habitat can become a trap. In November 2024, responders removed a cold-stressed manatee from a canal connected to the Tar River in Greenville. The animal had remained in North Carolina after the surrounding water cooled and could no longer survive there safely. It was transported to Florida, rehabilitated, and later returned to the wild (Gurney, 2024).

The rescue succeeded because someone recognized that the animal was in trouble and reported it.

It also showed the narrow line between opportunity and danger at the northern edge of a species’ range. A longer warm season may allow manatees to travel farther north, but an abrupt autumn cold spell can close that seasonal window very quickly.

Reaching North Carolina is only half the migration.

The animal must also leave in time.

Sea Cows Before Manatees

A living manatee in Onslow County may seem like a new arrival, but it belongs to a much older coastal story.

Manatees are sirenians, members of the group that also includes dugongs and their extinct relatives. The name “sea cow” comes from the way they graze, but the comparison ends there. Their closest living land relatives include elephants, not cattle (Reep & Bonde, 2021).

The first known sirenians appeared about 50 million years ago, during the Eocene (Domning, 2001; Reep & Bonde, 2021).

The world they entered was warmer than ours. Sea levels were high, and broad areas along the edges of the continents were covered by shallow seas.

The earliest known members of the group did not yet look like modern manatees. Animals such as Prorastomus sirenoides still had four usable limbs and probably divided their time between shallow water and land. A later early sirenian called Pezosiren portelli had the heavy ribs and plant-eating teeth associated with sea cows, but it also had four well-developed legs capable of supporting its body on land (Domning, 2001; Reep & Bonde, 2021).

Life reconstructions of two early sirenians from the Middle Eocene. Prorastomus sirenoides (left) and Pezosiren portelli (right) still retained four usable limbs, showing stages in the long transition from land-capable ancestors to fully aquatic sea cows. | Image credit: N. Tamura

They were the beginning of the transition, not its finished form.

As later sirenians spent more of their lives in water, their bodies changed around that way of life. The front limbs became flippers used for steering, handling vegetation, and moving along the bottom. The hind limbs became smaller until they were no longer visible outside the body. Their ribs and other bones became unusually thick and dense, adding weight that helped keep them submerged while they grazed (Domning, 2001; Reep & Bonde, 2021).

By the end of the Eocene, some branches had become fully aquatic and carried the basic sea-cow shape we would recognize today (Uhen, 2007).

But the place beneath those animals would not have looked like the Onslow County coastline we know.

The Atlantic had not yet arranged our barrier islands, sounds, inlets, and tidal creeks into their modern positions. Shorelines lay elsewhere as sea level rose and fell. Rivers carried different loads of sediment across a coastal plain that repeatedly shifted between dry land, estuary, and shallow sea (Harris & Laws, 1997)

There was no Surf City Pier. There was no fixed line where today’s sound ended and ocean began.

Around 50 million years ago, much of the southeastern United States looked very different. Warm, shallow seas covered broad areas of the coastal plain where the earliest sirenians began adapting to life in the water. | Image credit: Dinosaurpictures.org

Warm, shallow water stretched across parts of the region. Ancient sea cows moved through those waters, grazing over sediments that would later be buried, compacted, lifted, exposed, and cut through again by waves and rivers (Harris & Laws, 1997; Vélez-Juarbe et al., 2012).

Different branches took different forms.

Both branches inherited a horizontal tail used for propulsion. Modern manatees have a broad, rounded paddle, while dugongs have a divided fluke shaped more like that of a whale (Buchholtz et al., 2007; Reidenberg, 2007).

By the late Oligocene, roughly 23 to 28 million years ago, dugong relatives lived along the coast that would eventually become North Carolina. Fossils of the extinct sirenian, Crenatosiren olseni, have been reported from deposits associated with Onslow Beach (Reep & Bonde, 2021).

A fossil found today is therefore not simply the remains of an animal that once lived near our modern beach.

A fossilized dugong bone found on Topsail Beach. Long before modern manatees followed warm water north, other sirenians lived along this ancient coast. | Image credit: D. Ames

It is a piece of an older coastline carried into the present.

Those ancient animals were not Florida manatees, and a manatee visiting today is not the return of the same local species. It is a distant relative entering a kind of warm, shallow habitat that sirenians used here millions of years before the first recognizable version of our coastline existed.

That makes the animal both new and familiar.

The back rising beside a dock belongs to a visitor from Florida.

The larger story of sea cows along this coast is written much deeper beneath us.

The Shadow Beside the Boat

The most dangerous part of a manatee’s journey may be the water it shares with us.

Manatees often feed, rest, and travel close to the surface. They do not have a dorsal fin cutting above the water like a dolphin or shark. Their gray backs can disappear beneath glare, cloudy estuarine water, or the reflection of the sky.

Sometimes the animal itself is not the first thing we see.

As a manatee swims beneath the surface, each stroke of its tail may leave a smooth circular swirl behind it. These rings are called their “footprint”. One appears and begins to fade. Another forms several feet away. Together, they trace the path of an animal that may remain almost completely hidden (Factheu et al., 2023).

To a boater, those circles should mean slow down and look more carefully.

A manatee may remain almost completely hidden beneath the surface, leaving only bubbles and a series of smooth rings—its “footprint”—to mark where it has passed. | Image credit: buggybuddy, iNaturalist

A manatee can make a brief burst of speed to escape danger, but that does not mean it can always avoid a boat. In shallow water, there may be nowhere for it to dive. Even when the animal hears or feels a vessel approaching, it still needs enough time and space to move out of the path.

A propeller can cut deeply into the back or tail. The force of a hull or lower-unit strike can break ribs and cause internal injuries even when the outside of the animal shows little damage (Ackerman et al., 1995; Reep & Bonde, 2021).

Some manatees survive repeated strikes. The pale lines and deep cuts across their backs become permanent scars. Researchers can sometimes use those patterns to recognize the same animal when it is photographed somewhere else (Ackerman et al., 1995; Reep & Bonde, 2021).

A scar can help us follow a migration.

It is still a wound the animal should never have received.

Propeller scars remain visible across the backs of many manatees. These permanent patterns can help researchers recognize individuals—but each one records a collision the animal survived. | Image credit: USGS

When Kindness Creates Danger

A manatee approaching a dock can be hard to resist.

It may raise its face near a running hose or move toward water draining while someone flushes a boat engine. Offering a drink may feel like helping an animal that has traveled hundreds of miles.

The problem is not only the water it receives. It is what the manatee learns from the encounter.

Manatees remember useful places. If a dock provides freshwater or food, the animal may return. It may begin approaching other docks and boats expecting the same reward. Instead of avoiding propellers, fishing lines, and crowded marinas, it learns to remain close to them.

The behavior that looks friendly may therefore place the animal in greater danger during its next encounter (SC DNR, 2014).

Never feed a manatee or offer it water. Turn off dock hoses when they are not being used. Do not touch, pursue, surround, or enter the water to approach one (SC DNR, 2014).

Manatees are protected under the Marine Mammal Protection Act and the Endangered Species Act, but the more immediate reason is simpler: an animal traveling this far needs to remain able to find what it needs without depending on people (Baier, 2023; Marine mammal protection act of 1972; Perry Roberts & Wieting, 2001).

The safest manatee is not the one that trusts every boat.

It is the one that continues to give boats room.

Sharing the Water

Because manatees are still unusual here, North Carolina boaters may not think to look for them.

Summer also brings more boats into our inlets, sounds, and narrow channels. Many are operated by visitors who may be unfamiliar with the waterway, the shifting shoals, or the wildlife moving beneath them.

Navigation rules are not separate from wildlife protection.

No-wake and idle-speed zones are not just navigation rules. Slowing down gives boaters more time to see a manatee near the surface—and gives the animal more time to move out of the way. | Image credit: Save the Manatee Club

No-wake zones, speed restrictions, channel markers, right-of-way rules, and safe-distance requirements serve much the same purpose as traffic rules on land. They give everyone using a shared space enough time to see a hazard, understand what is happening, and respond.

That includes swimmers, paddlers, anglers, other boaters, and animals resting or traveling near the surface.

A person driving too quickly through a narrow waterway is not simply breaking a rule marked on a sign. Speed reduces the time available to notice a kayak, a child in the water, a shallow bar, a floating log, a sea turtle—or the faint circles left by a manatee just below the surface.

Watching the water means looking beyond the next marker (Calleson & Kipp Frohlich, 2007; Laist & Shaw, 2006).

Before starting an engine, check around the hull, stern, and dock. A manatee may be resting nearby without making a sound. When underway, polarized sunglasses can reduce glare and make dark shapes easier to see.

Watch for a rounded nose, part of a broad back, a patch of bubbles, or a trail of circular footprints. If a manatee is present, slow to idle, steer away from its path, and allow it to leave on its own.

Do not follow it for a photograph or block it against a dock, seawall, or shoreline. If you are in a boat, keep the vessel at least 50 feet away when possible and allow the manatee to choose its own path (Langtimm et al., 2004; USFWS, 2023)..

A photograph taken from a safe distance can still be useful, particularly if it shows scars on the back or tail (Langtimm et al., 2004) .

Every North Carolina sighting should be reported to UNCW’s Marine Mammal Stranding Program. Reports help researchers determine whether several observations involve the same animal, identify locations manatees use repeatedly, and record how early they arrive or how late they remain (UNCW, 2026).

Manatee sightings can be reported to UNCW at 910-515-7354.

An injured, entangled, distressed, stranded, or dead manatee should be reported immediately to the North Carolina Marine Mammal Stranding Network at 252-241-5119 (UNCW, 2026).

Do not try to free, move, feed, or treat the animal yourself.

A sighting report may feel like a small thing after the animal disappears.

Placed beside reports from other docks, piers, and waterways, it becomes part of the record researchers need to understand what is changing.

A New Summer Neighbor

For now, Onslow County is summer habitat at the northern edge of a Florida manatee’s range.

It cannot provide the dependable winter warmth of Florida’s springs and heated refuges. Autumn still places a limit on how long an animal can safely remain.

Summer may be becoming a different story.

Our sounds offer protected water, underwater vegetation, tidal creeks, and connected travel routes. If manatees continue finding those resources here, some may return. A female may eventually travel the route with a calf beside her. A place first reached through exploration may become part of a migration remembered from one year to the next.

That does not mean Onslow County is suddenly becoming another Florida.

It means the familiar landscape may be serving an animal many of us never expected to find within it.

The first sign may be no more than a circle opening across the water. Then another. A dark body rises where we expected a dolphin, takes one breath, and disappears beneath the surface.

What happens next depends partly on the animal—where it travels, what it finds, and whether it returns.

It also depends on what it finds from us.

A mother and calf surface together. If manatees continue finding food, shelter, and safe passage along our coast, places reached by one generation may become part of the next generation’s remembered route. | Image credit: B. Garrett

References

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July 23, 2026
What’s in Tail? What the Shapes of Caudal Fins can tell us about a fish

Watch fish for more than a few minutes, and something begins to stand out.

They do not all move through the water the same way.

A school of mullet slips across a creek with steady, effortless motion. A red drum twists through flooded marsh grass, turning between oyster clumps where shrimp and juvenile crabs have nowhere left to hide. A southern flounder erupts from the sand where, a moment before, there seemed to be nothing at all. Farther offshore, a little tunny slices through baitfish near the surface, while a cownose ray appears to fly beneath the water with its long tail trailing quietly behind.

The water is the same.

The rules of physics are the same.

But each animal has answered those rules differently.

A fish’s tail is far more than the end of its body. It is a record of how that fish survives. It can reveal where the fish spends its time, how it captures prey, how it escapes predators, how much energy it can afford to spend moving, and the role it fills within the larger ecosystem.

Like wings on birds or feet on mammals, the tail, known as the caudal fin, carries the shape of a life lived in a particular place.

To read a tail is to begin reading how fish use the water differently.

Every Fish Faces the Same Challenge

Moving through water is expensive.

Water is nearly 800 times denser than air (Vogel, 1996). Every sweep of the body pushes against it. Every turn creates resistance. Every burst of speed requires energy that cannot later be used to grow, migrate, reproduce, or avoid becoming another animal’s meal.

No fish escapes those limits.

Instead, each species works within them.

A fish moves as muscles contract in waves along the body, transferring force toward the caudal peduncle, the narrow region where the body meets the tail (Borazjani & Daghooghi, 2013; Sfakiotakis et al., 1999). From there, energy reaches the caudal fin. Each sweep of the tail pushes against surrounding water, creating pressure differences and rotating vortices that help produce forward thrust (Borazjani & Daghooghi, 2013; Maia et al., 2021).

Before the tail ever pushes against the water the body has already done the work. The caudal peduncle is where that power is passed to the tail. | Image credit: Louisiana Department of Wildlife & Fisheries

The tail is where the body’s power meets the water.

Yet the same basic problem has produced many different solutions.

Some fish are built for steady cruising. Others are built for sudden bursts. Some rely on tight turns. Some barely use the tail in the way we expect at all.

There is no perfect fish tail.
There are only tails shaped by different lives.

A fish that spends its life crossing miles of open water faces different problems than one weaving through flooded marsh grass. A predator that depends on surprise needs something different than one chasing baitfish across the surface. Even the bottom itself asks different things of the animals that live there.

Every tail that follows is one answer to those demands.

The Tail Never Works Alone

It is easy to focus on the tail because it is the most visible part of the movement.

But no fish swims with its tail alone.

The body determines how much drag the fish creates. The muscles generate the force. The caudal peduncle channels that force into the tail. Pectoral fins stabilize, steer, brake, or produce lift. Even the stiffness of the body changes how efficiently motion travels through the water.

A tuna is not fast because of its crescent tail alone. Its narrow caudal peduncle, streamlined body, stiff swimming motion, finlets, and powerful muscle arrangement all work together to conserve energy while moving through open water.

A red drum is not shaped for that same kind of movement. Its broader body, muscular peduncle, and less deeply forked tail serve a different purpose in a different landscape.

A flounder’s tail only makes sense after the rest of the fish has flattened into the bottom.

A shark’s tail cannot be understood without its pectoral fins.

The tail is part of a system (Lauder & Drucker, 2004; Sfakiotakis et al., 1999).

And that system is built around how the animal earns its living.

Built to Cross Open Water

Away from oyster reefs, marsh grass, docks, and submerged roots, the water opens.

There are fewer places to hide.

Prey may be scattered across greater distances.

Movement becomes less about turning around obstacles and more about conserving energy across space.

Watch Spanish mackerel feeding from a pier in late summer and they rarely seem to stop moving. The same is true for little tunny exploding through bait schools just beyond the breakers. Their tails were never built for hovering over one patch of water. They were built for finding the next meal, wherever it happens to be.

Spanish mackerel, bluefish, Atlantic bonito, little tunny, and many jacks carry deeply forked or crescent-shaped tails (Lighthill, 1971; Song et al., 2020; Tack & Gemmel, 2022). Their narrow caudal peduncles and relatively stiff bodies limit unnecessary side-to-side motion, directing more of each tail beat into forward movement. The tall, narrow shape of the tail also reduces drag while allowing fish to maintain speed through repeated strokes.

Their speed is impressive.

But efficiency is the deeper story.

Out beyond the marsh and inlets, where prey may be separated by miles rather than feet, every unnecessary movement matters. A tail that saves a small amount of energy with each stroke can eventually become another mile traveled, another school of baitfish reached, another day survived.

In open water, the tail becomes a tool of endurance.

Built for Split-Second Decisions

The marsh asks something different.

As the tide rises, red drum move into flooded Spartina where shrimp, juvenile blue crabs, and small fishes scatter through stems and oyster clusters. Sheepshead pick around pilings and shell edges. Black sea bass patrol reefs where every ledge may conceal prey or danger. Oyster toadfish wait in crevices, relying less on pursuit than on the suddenness of their strike.

These fishes do not all carry identical tails or hunt in exactly the same way.

None of them needs to cross open water all day.

They need control.

Every oyster shell, grass stem, piling, and dock creates another obstacle. The fish that succeeds here is rarely the fastest. It is the one that can change direction before its prey—or predator—does.

Compared with the narrow crescents of open-water cruisers, rounded, truncate, and slightly emarginate tails move their broader bodies through water (Song et al., 2020; Tack & Gemmel, 2022). That creates more drag, but it also allows the fish to push hard against the water at low speeds, accelerate more quickly, stop abruptly, and turn within confined spaces. A broad, muscular caudal peduncle helps deliver power immediately rather than conserving energy over long distances.

Other fins join in. Pectoral fins brake and steer. The body bends around obstacles. The tail supplies the final shove that send the fish around an oyster clump or into a pocket of flooded grass.

In a maze of oyster reefs, roots, pilings and marsh grass, turning one body length tighter can matter far more than maintaining speed over ten miles.

This type of tail reflects that reality.

Built to Become the Bottom

Few fishes rewrite the body plan as dramatically as a southern flounder.

It does not begin life looking like the fish we recognize.

As a larva, it swims upright with one eye on each side of the head, shaped much like other young fishes drifting through the water column. Then the transformation begins.

One eye slowly migrates across the skull (Okada et al., 2003). The body flattens. Pigment concentrates on what becomes the upper surface. The fish settles onto one side and begins living as part of the seafloor (Midway et al., 2024).

Most people notice the eyes.

But the tail changed jobs, too.

A flounder does not need a tail built for constant cruising. It needs one capable of launching a body that has already disappeared. The fish may remain motionless on sand or mud until a shrimp or small fish comes close enough. Then the body bends, the tail snaps, and the flounder surges forward in a short, explosive burst before settling back into the bottom (Midway et al., 2024).

Its tail serves as surprise.

On an open sandy bottom, there may be no grass, reef, or submerged root behind which a predator can wait. The flounder solves that problem by matching the bottom beneath it, sometimes shifting its color and pattern as the surrounding sediment changes.

Rather than finding cover, the flounder became the cover.

Its tail became the spring that launches an attack from a place prey never realized was occupied.

Built for Places Others Cannot Reach

Some fish survive by entering spaces where others cannot follow.

American eels move through tidal creeks, undercut banks, submerged roots, culverts, marsh edges, and dark spaces beneath docks where a stiffer fish body would become a liability.

Their dorsal, caudal, and anal fins merge into one continuous ribbon (Stin et al., 2024). Instead of relying on distinct tail beats alone, waves of motion travel along much of the body, allowing the eel to bend through narrow openings and complex structure.

Speed is not the point.

Access is.

Yet, the same flexible body that lets an eel disappear beneath roots or slip through a flooded marsh also carries it across an ocean.

American eels hatch in the Sargasso Sea and reach the North American coast after drifting within ocean currents as transparent, leaf-shaped larvae (Secor, 2015; Tsukamoto, 2009). They enter estuaries as glass eels and gradually develop the long, muscular bodies that will carry them through tidal creeks, rivers, ponds, and wetlands.,

Years later, mature eels reverse that journey. They leave inland and coastal habitats and return toward the Sargasso Sea to spawn.

They do not cross ocean like tuna. Rather that holding most of the body stiff and driving a narrow tail rapidly from side to side, an eel sends broad waves of motion along its body (Stin et al., 2024). That swimming style creates more resistance at high speeds, but it remains effective over long distances and across changing environments.

One body design solves two very different problems: it allows the eel to move through open water, climb through a watershed, pass beneath roots and around obstructions; and the other allows it to eventually return to sea.

Its strength is not mastery of one kind of water. It is the ability to keep moving as the water changes. Flexibility opens doors that speed never could.

When the Tail Stops Being the Engine

At first glance, rays appear to have dramatic tails.

Atlantic stingrays, southern stingrays, and cownose rays all trail long, whip-like tails behind wide bodies moving through coastal waters, tidal creeks, sounds, and inlets.

But watch one closely and the story changes.

The tail is not doing most of the swimming.

The large pectoral fins are (Rosenberger, 2001).

Watch a cownose ray passing beneath the surface seems to fly through the water. Each pointed wing rises and falls in a smooth stroke, producing the thrust that carries the ray forward. It’s tail follows behind, sometimes so quietly that it appears almost disconnected from the movement of the animal.

Closer to the bottom, Atlantic and southern stingrays use their broad discs differently. Their pectoral fins ripple or undulate as they move over sand and mud, where they can settle into the sediment and wait nearly unseen. Once propulsion shifted from the tail to the expanded pectoral fins, the tail was no longer required to serve as the main engine (Rosenberger, 2001).

But it did not become useless.

These rays carry one or more serrated, venomous spines on or near the base of the tail. The spine is not used to hunt. It is defensive, capable of discouraging a shark or other predator that attacks from behind or above (Maia et al., 2012).

The placement of the tail also reflects how each ray lives. Bottom-dwelling stingrays can lift and swing it when threatened, especially when pressure from above traps the animal against the sediment. Cownose rays spend more time actively swimming with the tail streaming behind their wing-driven bodies.

The engine moved into the wings.

The tail was free to serve another purpose.

When Lift Matters

Sharks carry another kind of solution.

Unlike most bony fishes, sharks do not have a swim bladder to help regulate buoyancy (Maia et al., 2012). Their position in the water depends on several features working together: an oil-rich liver, body shape, pectoral fins, and the tail.

In many sharks, the upper lobe of the caudal fin is longer than the lower lobe. This heterocercal tail helps generate thrust while also influencing lift and body angle as the shark moves forward (Thomson, 1976; Maia et al., 2012). The pectoral fins, and in hammerhead sharks – their heads, help balance those forces, acting like underwater wings that stabilize the animal in the water column.

A shark’s tail and pectoral fins are not separate stories.

They are part of the same swimming system. But that system is adjusted for different lives.

A bull shark moving through a muddy estuary needs power at lower speeds and enough control to follow prey through channels, shorelines, and changing currents. A blacktip chasing anchovies near the breakers depends more heavily on speed and rapid changes in direction as a bait school folds and scatters around it. Atlantic sharpnose sharks remain active over sandy bottoms and within coastal food webs where they pursue fishes, shrimp, squid and other available prey.

Their tails share the same basic shark pattern, but they do not carry identical proportions. Differences in lobe length, stiffness, body shape, and musculature change how each species uses the pattern to transform into movement.

Farther offshore, the thresher shark pushes the design toward an extreme. Its greatly elongated upper tail lobe is not only part of the swimming system; it is also a hunting tool. The shark accelerates toward schooling fish and sweeps its tail through the water, gathering the school into a tighter pod to consume more fish at a time (Oliver et al., 2013).

Even among sharks, the tail is not one solution.

It changes as the shark’s habitat, prey, and method of hunting change with it.

Every Tail Has a Price

If one tail shape were truly best, fish would all look much more alike.

They do not.

Every tail carries a trade-off.

Evolution does not build perfect designs (Lauder & Drucker, 2004; Secor, 2015).

It builds workable compromises.

Every advantage comes with something surrendered. A narrow, deeply forked tail can conserve energy across open water but cannot push against the water at low speeds like a broad, rounded tail. A fish built to spin through marsh grass cannot match the endurance of a pelagic hunter. A flattened body and explosive tail make the flounder a nearly invisible ambush predator, but not a long-distance cruiser. The eel’s flexibility opens routes through an entire watershed, even though it cannot slice through water like a mackerel.

These are not failed versions of some ideal fish. They are specialists. Nature is full of specialists because environments reward specialists.

Each has inherited a way of moving that makes certain opportunities possible while placing others beyond reach. Over generations, the fish that moved well enough to feed, escape, migrate, and reproduce within a particular landscape passed that arrangement forward.

A tail is therefore more than a solution to water resistances. It is a compromise between everything an animal might do and the few things it must do well. Not a movement toward perfection – but towards belonging.

Reading the Water Differently

The next time you look at a fish, try not to begin with color.

Watch how it moves.

A steady glide across open water tells one story. A sudden turn among oyster shells tells another. A burst from the sand reveals a predator that survived by disappearing. A ray moving like a winged shadow reminds us that the tail is not always the engine. A shark’s movement shows how lift, thrust, and balance must work together in an animal without a swim bladder.

Long before we know a fish’s name, its movement has already begun telling us where it lives, how it hunts, how it escapes, and how it fits into the larger food web.

A tail gives us a place to begin..

It is the visible record of problems solved repeatedly: distances crossed, obstacles cleared, prey overtaken, predators avoided, and energy conserved..

Once we recognize these patterns, we no longer only see a fish passing through water.

We begin to see the life that shaped it.

By the time a fish passes from view, its tail has already revealed the story of the life it was built to live. | Image credit: Explore.org, Frying Pan Tower

References

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Lauder, G., & Drucker, E. (2004). Morphology and experimental hydrodynamics of fish fin control surfaces. IEEE Journal of Oceanic Engineering, 29(3), 556-571. https://doi.org/10.1109/joe.2004.833219

Lighthill, M. J. (1971). Large-amplitude elongated-body theory of fish locomotion. Proceedings of the Royal Society of London. Series B. Biological Sciences, 179(1055), 125-138. https://doi.org/10.1098/rspb.1971.0085

Maia, A. M., Wilga, C. A., & Lauder, G. V. (2012). Biomechanics of Locomotion in Sharks, Rays, and Chimeras. In Biology of Sharks and Their Relatives (2nd ed.). CRC Press.

Midway, S. R., Scharf, F. S., Dance, M. A., Brown-Peterson, N. J., Ballenger, J. C., Beeken, N. S., Borski, R. J., Darden, T. L., Erickson, K. A., Farmer, T. M., Fincannon, A., Godwin, J., Graham, P. M., Green, J. L., Hershey, H., Kiene, D., Lee, L. M., Loeffler, M. S., Markwith, A., … White, S. B. (2024). Southern flounder: Major milestones and remaining knowledge gaps in their biology, ecology, and fishery management. Reviews in Fisheries Science & Aquaculture, 32(3), 450-478. https://doi.org/10.1080/23308249.2024.2341017

Okada, N., Takagi, Y., Tanaka, M., & Tagawa, M. (2003). Fine structure of soft and hard tissues involved in eye migration in metamorphosing Japanese flounder (Paralichthys olivaceus). The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology, 273A(1), 663-668. https://doi.org/10.1002/ar.a.10074

Oliver, S. P., Turner, J. R., Gann, K., Silvosa, M., & D’Urban Jackson, T. (2013). Thresher sharks use tail-slaps as a hunting strategy. PLoS ONE, 8(7), e67380. https://doi.org/10.1371/journal.pone.0067380

Rosenberger, L. J. (2001). Pectoral fin locomotion in Batoid fishes: Undulation Versus oscillation. Journal of Experimental Biology, 204(2), 379-394. https://doi.org/10.1242/jeb.204.2.379

Secor, D. H. (2015). Migration ecology of marine fishes. JHU Press.

Sfakiotakis, M., Lane, D., & Davies, J. (1999). Review of fish swimming modes for aquatic locomotion. IEEE Journal of Oceanic Engineering, 24(2), 237-252. https://doi.org/10.1109/48.757275

Song, J., Zhong, Y., Du, R., Yin, L., & Ding, Y. (2020). Tail shapes lead to different propulsive mechanisms in the body/caudal fin undulation of fish. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 235(2), 351-364. https://doi.org/10.1177/0954406220967687

Stin, V., Godoy‐Diana, R., Bonnet, X., & Herrel, A. (2024). Form and function of anguilliform swimming. Biological Reviews, 99(6), 2190-2210. https://doi.org/10.1111/brv.13116

Tack, N. B., & Gemmell, B. J. (2022). A tale of two fish tails: Does a forked tail really perform better than a truncate tail when cruising? Journal of Experimental Biology, 225(22). https://doi.org/10.1242/jeb.244967

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Vogel, S. (1996). Life in moving fluids: The physical biology of flow (2nd ed.). Princeton University Press.

Wilga, C. D., & Lauder, G. V. (2002). Function of the heterocercal tail in sharks: Quantitative wake dynamics during steady horizontal swimming and vertical maneuvering. Journal of Experimental Biology, 205(16), 2365-2374. https://doi.org/10.1242/jeb.205.16.2365

July 11, 2026
How Sharks, Rays, and Ghost Sharks Read an Invisible Ocean

A shadow moves beneath the surface.

At first, it is only a darker shape inside darker water. Then the shape shifts, and the human mind does what it always does. It tries to make sense of what the eyes are seeing.

Fish? Ray? Shark? Something else?

We look harder. We search for a fin, a tail, a clear outline, some familiar clue that lets us name the animal before it disappears again. That is how we enter the ocean. We enter it as visual animals.

We rely on sight first.

On land, that makes sense. We look both ways before crossing a street. We recognize faces. We read signs. We notice color, distance, motion, and shape. Even when our other senses help us understand the world, sight usually leads the way.

But the ocean is not built for human sight.

Light bends and scatters. Sand clouds the water. Storms stir sediment. Tannins darken creeks and estuaries. Waves break the surface into fragments. A fish can vanish into shadow. A ray can disappear beneath one thin layer of sand. A shark can move through water we are staring directly into and still be almost impossible to see.

To us, the ocean often becomes less clear the moment we step into it.

To sharks, rays, skates, sawfish, and chimaeras, that same water is not empty. It is not silent. It is not blank.

It is filled with signals.

These animals belong to a group called chondrichthyans, fishes with skeletons made of cartilage instead of bone. Sharks, rays, skates, sawfish, and chimaeras all belong here. We often separate them by the way they look: sharks with their familiar fins and teeth, rays flattened against the bottom, skates moving quietly over sand, sawfish carrying a toothed rostrum, and chimaeras drifting through deeper water like something half-remembered from another age.

But they are connected by more than cartilage.

They share sensory worlds that are difficult for us to imagine because they include abilities we do not have in the same way. They use sight, smell, hearing, touch, and temperature, but they also read movement through the water with the lateral line. They detect weak electrical fields with ampullae of Lorenzini. They interpret the ocean through pressure, vibration, chemistry, contrast, motion, and life itself (Collin, 2012; Hart & Collin, 2015).

We may look into murky water and see almost nothing.

They may be reading an entire landscape.

The Ocean as a Different Kind of World

Sometimes, we do sense the world in ways that remind us we are not only visual.

A storm approaches, and some people feel pressure before the first drop of rain falls. Sinuses tighten. Migraines build. The air feels different. We walk into a dark room and suddenly sound becomes more important. A creak in the corner, a moving shadow, or a change in the air near our skin, these matter.

We still try to confirm everything with sight, but when sight weakens, the rest of the body steps forward.

Now imagine living in a world where sight is helpful, but never enough.

Water carries information differently than air. A fish swimming does not simply move from one place to another. It pushes water aside. A tailbeat sends movement outward. A struggling animal leaves a different pattern than a calm one. A crab moving under sand may be hidden from view, but its body is still alive. Muscles contract. A heart beats. Nerves fire. Gills pump. Chemicals dissolve and drift.

Every animal changes the water around it.

For chondrichthyans, that matters.

A shark does not have to wait until prey forms a perfect picture in front of its eyes. A ray does not need the seafloor to look busy in order for it to be busy. A skate does not need color to know the bottom is alive. A sawfish does not carry its rostrum only as a weapon. A chimaera in deep water does not move through darkness without information.

Their sensory systems allow them to gather information across different distances and conditions. Smell, hearing, vision, lateral line detection, and electroreception do not work as separate switches. They overlap, reinforce, and sometimes compensate for one another depending on habitat, prey, visibility, and behavior (Gardiner et al., 2014; Hart & Collin, 2015).

Their world is not less detailed than ours.

It is detailed differently.

Their world is not less detailed than ours.

It is detailed differently.

A Shark’s World

A shark moving through shallow water can be almost impossible to see until it is already there.

Its body color may match the shifting bottom. Sunlight breaks over its back. Ripples blur the outline. The water may be green, gray, brown, or blue depending on the tide, weather, and sediment. Even in clear water, the shark can appear as a shadow before it appears as an animal.

To us, the shark is barely more than a shadow. To the shark, the water is already full of information — movement, pressure, chemistry, and weak electrical signals that help it read the world before sight alone confirms what is there. | Image credit: D. Remmers

But the shark’s awareness does not begin when our eyes finally notice its shape.

Long before sight confirms what is nearby, other senses may already be gathering information. A fish moving ahead sends pressure changes through the water. A school changing direction creates a pattern of motion. A wounded or stressed animal moves differently than a calm animal. Muscle contractions and heartbeats create weak electrical fields. Odors move through the water as chemical trails.

To us, the ocean may look open.

To a shark, it is full of clues.

The lateral line runs along the body and head and helps detect movement, vibration, and changes in water flow. It is not vision, but it can reveal that something nearby is moving. It can help an animal sense direction, intensity, and disturbance (Webb, 2023).

The ampullae of Lorenzini add another layer. These small, jelly-filled pores are concentrated around the head and snout. They detect weak electrical fields produced by living animals. This is especially useful at close range, when prey is hidden, when light is low, or when the final decision about an object must be made (Bellono et al., 2017; Hart & Collin, 2015).

A hammerhead makes this easier to picture.

Its wide head may look strange to us, but that shape spreads sensory structures across a broader surface. Moving over the bottom, a hammerhead can sweep its head across the sand. A buried ray may be invisible to human eyes. To the shark, the sand may not be silent at all.

This is where our imagination reaches its limit.

We can compare electroreception to the feeling of standing near an electrical charge or sensing the strange energy in the air during an intense lightning storm. But even that comparison is weak. We do not move through the world constantly reading tiny electrical fields from other living bodies.

Sharks do.

Their world is not a human picture with extra details added. It is a different kind of picture altogether.

Sight Still Matters

Sharks have eyes, and those eyes matter.

They detect contrast, motion, light, shadow, and shape. Many sharks are well suited for low-light conditions. Some have reflective structures behind the retina that help make better use of dim light. This is part of why shark eyes may appear to glow when light catches them underwater. Vision is one piece of a broader sensory strategy that changes by species, habitat, and ecological role (Collin, 2012; Hart & Collin, 2015).

But shark vision is not human vision.

Humans rely heavily on color. We use it to separate objects, judge ripeness, read warning signs, choose clothing, and notice differences in our surroundings. Sharks appear to rely less on color and more on contrast, brightness, movement, and shape. They only have one type of cone photoreceptor with many rods. This makes them more likely to be color blind or have very limited color discrimination (Hart et al., 2019).

That does not mean sharks see poorly.

It means color may not be the priority in their world.

In water, color disappears with depth and distance. Red fades quickly. Light changes constantly. Suspended particles blur edges. A fish flashing silver, a silhouette against the surface, or a sudden burst of movement may matter more than whether something is red, green, or blue.

A shark’s visual world may be built more from shadow, contrast, motion, and form than from color.

This is important when we talk about shark-human encounters. A swimmer, surfer, or splashing person at the surface is not being interpreted through human categories. The shark is not thinking “person.” It is receiving a mixture of signals: movement, vibration, silhouette, chemical traces, electrical fields, contrast, and the surrounding activity of fish or bait.

Sometimes, those signals may be confusing.

The phrase “mistaken identity” is often used to explain shark bites, but it should be used carefully. It does not explain every bite. It does not mean sharks are foolish. It does not mean they are unable to tell anything apart. It means that, in some situations, the clues available to the shark may overlap with the clues produced by prey. This is why some human silhouettes at the surface can resemble seal and sea lion prey to a shark, especially when viewed from below and under certain movement conditions (Ryan et al., 2021).

We know a version of this ourselves.

Walk through a dark house at night and hear something move in the corner. Your eyes search for shape. Your ears sharpen. Your body tenses before your mind has enough information. You move closer. Maybe you speak into the darkness. Maybe you reach out with your hand or nudge with your foot.

Then the light turns on, and the intruder becomes a chair with a jacket over it.

You were not hunting the chair.

You were investigating a signal you did not fully understand.

A shark does not have hands. Its fins move it through the water, but they do not investigate the way our fingers do. Its mouth becomes one of the ways it tests the world. That does not make the animal cruel or mindless. It means its body solves a sensory problem differently than ours does.

For people, that difference can be dangerous. An investigative bite can still cause serious injury. But it is not the same thing as a shark deciding humans belong on the menu.

Most of the time, we do not match the full pattern of shark prey.

We smell different. We move differently. We do not behave like fish, rays, turtles, seals, or other natural prey. But in the wrong place, at the wrong time, with the wrong signals around us, we can become part of a confusing sensory scene.

This is why swimming near active fishing, bait, chum, or dense schools of baitfish matters. The shark is not being summoned by evil intent. It is following information.

The ocean is speaking in the language it knows.

The Ocean as Touch and Sound

A school of fish turns all at once.

There is no visible leader. No signal we can see. One moment the school moves in one direction, and the next it shifts like one silver body. Each fish keeps its place without crashing into the others. The turn happens faster than sight alone seems able to explain.

This is one of the easiest ways to understand the lateral line.

Fish do not only see their neighbors. They feel the water their neighbors move. Each tailbeat, each change in direction, each surge away from danger creates tiny changes in water motion. Those changes travel across the bodies of nearby fish.

The lateral line detects those movements.

This sensory system is found in many fishes, not only sharks and rays. It helps animals orient in currents, avoid obstacles, respond to predators, follow prey, and move together in groups. It turns water into a kind of touch-field. The structure and function of the lateral line vary across fishes, but its role in detecting water motion is central to how aquatic animals interpret movement around them (Webb et al., 2023).

In sharks, this sense is closely tied to the way sound and vibration move through water. We often think of hearing as something that happens only through ears, but underwater, the whole body can become part of how an animal detects vibration. The lateral line helps a shark feel nearby water movement across its body, while the inner ear detects sound and orientation. Together, these systems make the shark’s body seem less like a body moving through water and more like an instrument tuned to it (Collin, 2012; Hart & Collin, 2015; Webb, 2023).

For a shark, this means the ocean is never simply open space.

It has texture.

A mullet swimming calmly leaves one kind of disturbance. A frightened fish leaves another. A crab moving across the bottom creates a different pattern than a shrimp flicking backward. Waves break. Boat motors pulse. Rain hits the surface. Feet shuffle through sand. A fish struggles on a line. A school turns.

Each movement changes the water.

We might stand at the edge of an inlet and see only ripples. A shark, ray, or skate moving through that same water may sense layers of motion overlapping one another. Some signals fade into background noise. Others stand out.

A calm fish and a frantic fish do not write the same message.

Along the Onslow County coast, this matters. Our nearshore waters are not always clear. Wind, tide, storms, suspended sand, tannins from creeks, plankton blooms, and wave energy all change visibility. Animals living here cannot depend on sight alone in a world where the water can cloud overnight.

A shark does not need a perfect view to know something is moving.

A ray does not need to see every small animal beneath it to know the bottom is alive.

A fish in a school does not need to wait for its neighbor to bump into it before turning.

Water carries the conversation.

The Hidden Electricity of Living Things

The sandy bottom can look blank.

A flat stretch of seafloor may seem empty to us, especially when nothing obvious moves. But beneath that surface may be worms, clams, crabs, shrimp, small fish, or rays. Some are hiding. Some are resting. Some are feeding. Some are waiting for the tide to shift.

To our eyes, they disappear.

To an animal with electroreception, hidden does not always mean gone.

Ampullae of Lorenzini allow sharks, rays, skates, sawfish, and chimaeras to detect weak electrical fields. These fields are extremely small, but they are part of what living bodies produce. Muscles contract. Hearts beat. Nerves fire. In saltwater, and especially at close range, those signals can become useful information (Bellono et al., 2017; Collin, 2012).

The sand may cover the animal.

It does not erase it.

This is especially important for animals that feed along the bottom. A shark searching a flat may combine smell, movement, vision, and electroreception. A ray may use similar signals to locate prey in sediment. A sawfish carries this ability into one of the strangest-looking structures in the sea.

Electroreception also reminds us that the ocean is not only a visual habitat.

It is a habitat of fields and traces.

We are used to thinking an animal is hidden when we cannot see it. But concealment depends on who is looking, and how.

A crab hidden from a bird may not be hidden from a ray.

A ray hidden from us may not be hidden from a hammerhead.

A fish buried beneath sand may still be detectable to a predator passing overhead.

This does not make the ocean more frightening.

It makes it more alive.

A Ray’s World

A stingray resting in shallow water can vanish beneath a thin covering of sand.

Only the eyes may remain visible. Sometimes even those are difficult to see. The body becomes part of the bottom: a soft outline, a slight rise, a place where the sand seems smoother than the sand around it.

To us, a buried ray may feel like a surprise.

To the ray, the world is still open.

Its eyes sit high on the body, watching the water above. Its mouth is underneath, positioned for feeding along the bottom. Its spiracles allow water to move across the gills while the animal rests or feeds close to the seafloor. Its lateral line and electrosensory system help detect movement and electrical signals nearby (Bedore et al., 2014; Collin, 2012).

The ray does not need to see the world exactly as we do.

It lives in layers.

Above, there may be predators, shadows, swimmers, boats, birds, and changing light. Below and around it, there may be worms, shrimp, crabs, clams, and small fish hidden in or on the sediment. A ray’s flattened body makes sense in this in-between place. It is shaped for bottom life, but it is not cut off from the water column above it.

Its eyes are important, but they are not everything.

Rays can detect contrast, shape, motion, and orientation. Some rays may have stronger color discrimination than sharks. Some also have a reflective layer in the eye, the tapetum lucidum, that helps make better use of dim light (Hart et al., 2019). We often compare this to the eye shine seen in cats and other animals at night.

But a ray buried in sand is not simply waiting with its eyes.

It is reading pressure. It is reading smell. It is reading electrical traces from animals moving nearby. It is receiving information through more than one doorway.

This is why the stingray shuffle matters.

A stingray spine is not used to chase people. It is a defense. When a ray is stepped on or startled from above, the spine can rise quickly. The injury is real, but the behavior is not personal. The ray is responding to pressure and threat in the only way its body allows.

A shuffled foot gives warning.

It tells the hidden animal that something large is moving through the sand and gives it a chance to leave before contact happens.

That small human behavior recognizes something important: the shallow edge is shared space.

We may be wading through it.

The ray may be living in it.

A Skate’s World

Skates are often confused with rays.

From above, the difference may not seem important to a casual observer. Both are flattened. Both move close to the bottom. Both can disappear into the shape and color of the seafloor.

But skates are not simply stingrays without drama.

They are their own kind of bottom reader.

Like rays, skates use sensory systems that help them understand the seafloor without relying only on sight. Their eyes are positioned on top of the body, while the mouth is underneath. Their flattened form allows them to move close to the bottom, where many small animals hide in sand, shell hash, mud, and seagrass.

A skate moving over the bottom is not only looking.

It is sampling the landscape through touch, smell, pressure, and electricity.

This makes the bottom less like a floor and more like a page. Each small animal leaves some sign: a movement, a chemical trace, a disturbance, a weak electrical field, a change in sediment (Bedore et al., 2014).

Skates remind us that not every chondrichthian is built around speed, teeth, and open-water pursuit. Some are built for patience. Some are built for closeness. Some read the world by staying near the place where water meets sediment.

Along our coast, that meeting place matters.

Sand flats, tidal creeks, inlets, oyster edges, and shallow nearshore bottoms are not empty spaces between “real” habitats. They are habitats. They hold the smaller lives that larger animals follow.

To understand the skate or ray, we have to stop seeing the bottom as blank.

A Sawfish’s World

A sawfish looks almost impossible the first time you really consider it.

It has the flattened body of a ray, but extending from the head is a long, tooth-edged rostrum — the “saw” that gives the animal its name. It looks like a weapon, and it can be used that way. Sawfish can swing the rostrum through schools of fish, stunning or injuring prey. It can also help defend the animal.

But the saw is not only a blade.

It is also a sensory surface.

The rostrum contains electroreceptive organs, ampullae of Lorenzini, that help detect weak electrical signals from nearby animals. In other words, the part of the animal that looks most like a weapon is also part of how it reads the world.

That changes the way we see it.

A sawfish is not blindly sweeping through water with a strange tool attached to its face. It is carrying a detector through the habitat ahead of its body. The saw helps locate prey. It helps interpret the space in front of the animal. It turns the water ahead into information (Wueringer et al., 2011; Wueringer, 2012).

This is different from the way we usually imagine rays and skates sensing the bottom.

A ray or skate often reads the world close to and beneath its flattened body. Its mouth is underneath. Its eyes look upward. Its sensory systems help it interpret the bottom as it rests, glides, or feeds along the sediment. A sawfish, however, extends part of that sensory world forward. The rostrum projects into the water ahead of the body, giving the animal information about prey before the prey reaches the mouth or passes beneath the disc.

That changes the animal’s sensory shape.

A sawfish does not only sense what is under it.

It can sense what is ahead of it.

The saw becomes a leading edge of perception. As the animal moves, the rostrum samples the space in front of the body. A fish hidden in murky water, a prey item moving near the bottom, or a school passing just ahead may be detected through electrical signals before the sawfish strikes. The same structure that can stun prey can also help find it (Wueringer et al., 2011; Wueringer, 2012).

That is what makes the sawfish so fascinating.

The feature that looks most dramatic to us is not simply for attack or defense. It is part of the animal’s sensory map. It stretches the invisible world forward.

Smalltooth sawfish were historically found as far north as North Carolina, but today they are generally associated with Florida waters in the United States (NOAA Fisheries, 2025). Seeing one along the Onslow County coast would be unusual. Still, they belong in this story because they show how far the chondrichthian sensory world can go.

A body part we notice for its shape may be important because of what it senses.

The ocean often works that way.

The feature that looks strange to us may be perfectly sensible in the world where the animal lives.

A Chimaera’s World

Far from the beach, beyond the bright shallows and beyond the places most of us will ever swim, chimaeras move through deeper water.

They are sometimes called ghost sharks, though they are not true sharks. They are relatives within the larger chondrichthian group, with cartilage skeletons and a long evolutionary history. Their bodies seem stitched together from familiar parts in unfamiliar ways: large eyes, winglike fins, smooth skin, and tooth plates instead of the replaceable teeth we associate with many sharks.

They look like animals from the edge of imagination.

But their strangeness is not random.

Many chimaeras live in deep, dim environments where sight has limits. In that world, an animal cannot depend on color and daylight the way we do at the surface. Light fades. Pressure increases the deeper you go. The landscape becomes colder, darker, and harder for human senses to understand.

A chimaera still has eyes, and those eyes can be large. But like other chondrichthyans, chimaeras also use sensory structures that detect electrical fields. In deep water, where prey may be sparse and visibility limited, the ability to detect life without needing a clear visual image becomes essential (Bottaro et al., 2022).

A chimaera reminds us that “seeing” does not always mean forming a bright picture.

Sometimes it means detecting what is alive in darkness.

That may be the hardest part for us to imagine. We tend to picture the deep sea as emptiness because our senses fail there. But the animals that live there are not moving through emptiness. They are moving through a world shaped by pressure, chemistry, temperature, vibration, faint light, and electrical traces.

The deep sea is not empty.

It is written in a language we barely read.

Reading the Ocean Instead of Fearing the Shadow

It is easy to turn sharks into symbols.

Fear does that. So do movies, headlines, and stories told from the shoreline after something frightening happens. A fin becomes a threat. A bite becomes proof of intent. A shadow becomes a monster.

But the real animal is more interesting than the symbol.

A shark is not moving through the water thinking like a person. A ray is not buried beneath the sand waiting for a human foot. A skate is not a flat shadow without a story. A sawfish is not only a saw. A chimaera is not only a ghost.

Each animal is built for a sensory world we do not naturally share.

That does not mean we ignore risk. Quite the opposite. Understanding these senses helps us behave with more respect in the water. We can avoid swimming near fishing activity, bait, or chum. We can pay attention when baitfish are schooling near shore. We can shuffle our feet in ray habitat. We can remember that murky water changes the way animals rely on different senses. We can stop assuming that clear human intent matters in an animal’s sensory landscape.

The ocean does not interpret us the way we interpret ourselves.

We may enter the water as swimmers, surfers, paddlers, anglers, or beachgoers. But to the animals already living there, we are also movement, pressure, chemistry, vibration, shadow, sound, and electricity.

We are part of the signal.

That is humbling, and it should be.

Our world is three-dimensional, but it is still mostly built around what we can see. Their world is three-dimensional too, but it includes layers we barely notice.

They are not seeing less of the ocean than we are. They are reading more of it differently. And maybe that is the point.

Standing at the edge of the ocean, we see waves, color, and surface. Beneath that surface, other animals are reading movement, pressure, chemistry, and electrical traces in ways we cannot naturally feel.

The shark may not be looking for us.

The ray may not be hiding from us.

The fish may not be moving randomly.

They are reading the ocean.

We are only beginning to learn the alphabet.

Standing at the edge of the ocean, we see waves, color, and surface. Beneath that surface, sharks, rays, skates, sawfish, and chimaeras read movement, pressure, chemistry, shadow, and electrical traces in ways we cannot naturally feel. | Image credit: A. Mitchell

References

Bangley, C. (2026, January 26). Sharks of NC. Coastwatch. https://ncseagrant.ncsu.edu/coastwatch/the-sharks-of-north-carolina/

Bedore, C. N., Harris, L. L., & Kajiura, S. M. (2014). Behavioral responses of batoid elasmobranchs to prey-simulating electric fields are correlated to peripheral sensory morphology and ecology. Zoology, 117(2), 95-103. https://doi.org/10.1016/j.zool.2013.09.002

Bellono, N. W., Leitch, D. B., & Julius, D. (2017). Molecular basis of ancestral vertebrate electroreception. Nature, 543(7645), 391-396. https://doi.org/10.1038/nature21401

Bottaro, M. (2022). Sixth sense in the deep-sea: The electrosensory system in ghost shark Chimaera monstrosa. Scientific Reports, 12(1). https://doi.org/10.1038/s41598-022-14076-2

Collin, S. P. (2012). The Neuroecology of cartilaginous fishes: Sensory strategies for survival. Brain, Behavior and Evolution, 80(2), 80-96. https://doi.org/10.1159/000339870

Gardiner, J. M., Atema, J., Hueter, R. E., & Motta, P. J. (2014). Multisensory integration and behavioral plasticity in sharks from different ecological niches. PLoS ONE, 9(4), e93036. https://doi.org/10.1371/journal.pone.0093036

Hart, N. S., & Collin, S. P. (2015). Sharks senses and shark repellents. Integrative Zoology, 10(1), 38-64. https://doi.org/10.1111/1749-4877.12095

Hart, N. S., Lamb, T. D., Patel, H. R., Chuah, A., Natoli, R. C., Hudson, N. J., Cutmore, S. C., Davies, W. I., Collin, S. P., & Hunt, D. M. (2019). Visual Opsin diversity in sharks and rays. Molecular Biology and Evolution, 37(3), 811-827. https://doi.org/10.1093/molbev/msz269

NOAA Fisheries. (2025). Smalltooth sawfish. NOAA. https://www.fisheries.noaa.gov/species/smalltooth-sawfish

Ryan, L. A., Slip, D. J., Chapuis, L., Collin, S. P., Gennari, E., Hemmi, J. M., How, M. J., Huveneers, C., Peddemors, V. M., Tosetto, L., & Hart, N. S. (2021). A shark’s eye view: Testing the ‘mistaken identity theory’ behind shark bites on humans. Journal of The Royal Society Interface, 18(183). https://doi.org/10.1098/rsif.2021.0533

Webb, J. F. (2023). Structural and functional evolution of the mechanosensory lateral line system of fishes. The Journal of the Acoustical Society of America, 154(6), 3526-3542. https://doi.org/10.1121/10.0022565

Wueringer, B. E. (2012). Electroreception in elasmobranchs: Sawfish as a case study. Brain, Behavior and Evolution, 80(2), 97-107. https://doi.org/10.1159/000339873

Wueringer, B., Peverell, S., Seymour, J., Squire, Jr., L., Kajiura, S., & Collin, S. (2011). Sensory systems in Sawfishes. 1. The ampullae of Lorenzini. Brain, Behavior and Evolution, 78(2), 139-149. https://doi.org/10.1159/000329515

July 3, 2026
The Marsh’s Quiet Workforce: More Than a Rabbit

More Than Meets the Eye

Spend enough time walking along a salt marsh and you’ll eventually stop noticing the marsh rabbits.

Not because they’ve disappeared.

Because they’ve become part of the landscape.

They feed quietly along the marsh edge, slipping into the grasses when startled before appearing again somewhere you didn’t expect. Some evenings you may count half a dozen. Other days you wonder if there were ever any there at all.

Unlike the brighter cottontails many people are used to seeing, marsh rabbits are darker, with coarse brown to reddish-brown fur, a grayish underside, and a rusty cinnamon patch along the back of the neck. Even the tail gives them away. Instead of flashing bright white, it appears darker and more bluish, one reason marsh rabbits have sometimes been called “bluetails” (Chapman & Trani, 2007; Chapman & Willner, 1981).

Like so much of the marsh, they’re easy to overlook.

A marsh rabbit may look like a familiar backyard visitor, but its role reaches far beyond the grass beneath it. | Image credit: skylarkymalarkey, iNaturalist

For more than a century, naturalists have described marsh rabbits (Sylvilagus palustris) by documenting where they lived, what they looked like, and what they ate (Rhoads & Young, 1897). Those observations gave us our first understanding of the species. Today, ecology invites us to ask a different question.

What happens because marsh rabbits are here?

The answer reaches far beyond the rabbit itself.

We often measure an animal’s importance by how exciting it is to watch.

The marsh doesn’t.

The marsh measures importance by how many lives are connected to one another (Soulé et al., 2003).

Following One Rabbit

If you’ve ever taken a science class, you’ve probably learned the First Law of Conservation of Energy: energy cannot be created or destroyed. It only changes form.

For many of us, that idea remained in a textbook or written across a classroom whiteboard. It became something to memorize rather than something we expected to witness.

Yet every walk beside a salt marsh quietly brings that principle to life.

Standing beside a marsh, it’s easy to underestimate what you’re seeing. From a distance, much of it appears to be little more than grass. Yet every growing season those grasses capture enormous amounts of energy from the sun, making salt marshes among the most productive ecosystems on Earth (Frizzell, 1988).

That productivity, however, cannot remain in the plants.

It has to move.

Imagine following a single marsh rabbit through its life.

Following one marsh rabbit means following the grasses, cover, and hidden pathways that connect it to the larger marsh. | Image credit: jorgenols, iNaturalist

At only about 2.5 to 3.5 pounds, its small body holds energy gathered first by the marsh plants around it (Chapman & Trani, 2007; Chapman & Willner, 1981).The grasses it consumes become muscle, bone, blood, fur, and new life. That rabbit may one day feed a hawk, an owl, a fox, a bobcat, or a snake. Throughout its life it supports parasites. After its death it feeds scavengers, fungi, bacteria, and countless decomposers before eventually returning nutrients to the marsh where another season of growth begins.

Nothing has appeared from nowhere.

Nothing has truly disappeared.

The energy has simply changed form.

Every day, marsh rabbits transform marsh vegetation into something that can support an entirely different community of organisms (Chapman & Trani, 2007; Chapman & Willner, 1981).

The rabbit isn’t the end of the story.

In many ways, it’s where the story begins.

More Than a Meal

Spend a few minutes watching a marsh rabbit and it may not seem particularly busy.

It grazes along the marsh edge, pauses to listen, slips into dense cover, then returns to feeding when the danger seems to have passed. At first glance, it looks like a small animal moving through its day.

But even before a marsh rabbit becomes food for something else, it is already shaping the marsh around it.

Every bite influences which plants are grazed and which continue growing (Conner & Cherry, 2017). As it moves between the marsh edge, nearby cover, and slightly higher ground, the rabbit is also moving through the boundary between habitats most of us see as separate. The same dense vegetation that protects the rabbit also provides shelter for insects, reptiles, amphibians, birds, and countless other small lives moving through the marsh (Canepuccia et al., 2023; Larsen & Gray et al., 2021; Wigley & Lancia, 1998).

A marsh rabbit browses at the edge, where each ordinary bite helps move energy through the landscape. | Image credit: cadecampbell, iNaturalist

This is why the rabbit matters before the hawk ever appears.

Its value is not limited to becoming prey. Its ordinary life helps move energy, shape vegetation, and connect habitats long before that energy travels farther up the food web (Chapman & Trani, 2007; Chapman & Willner, 1981; Conner & Cherry, 2017).

Perhaps that is the quiet work of a marsh rabbit.

Not simply feeding something else.

But helping hold together the conditions that allow so much else to live there.

Why There Are So Many

Sometimes marsh rabbits seem to be everywhere — in yards, along road edges, near parking lots, and wherever the Spartina meets slightly higher ground.

A young marsh rabbit beside an adult shows the visible side of abundance, but reproduction is only part of the story. | Image credit: Wolfgang, iNaturalist

The easy explanation is that rabbits reproduce quickly. They can produce several litters in a year, often three to seven, with roughly 15 to 20 young produced annually under favorable conditions (Holler & Conaway, 1979).

That is true, but it is not the whole story.

Nature rarely invests heavily in something that does not matter. In a marsh, abundance is not waste. It is part of the system.

Marsh rabbits live under constant pressure. Every choice — where to feed, when to move, when to freeze, and when to disappear into the grasses — is shaped by predators, tides, weather, and the daily balance between finding food and becoming food (Hill et al., 2019; Holler & Conaway, 1979).

Predators influence far more than the animals they catch. Their presence can change where prey feed, how long they remain exposed, and how energy moves through the landscape (Suraci et al., 2019). When predator communities shift, those changes can ripple through the food web in ways that affect many other species (Bransford et al., 2024; Jiménez et al., 2019) .

Seen this way, abundant marsh rabbits are not simply evidence of successful reproduction.

They are evidence of how much work this one ordinary species performs.

The Rabbit You Didn’t See

Perhaps this also explains something you’ve probably noticed yourself.

One moment several marsh rabbits are feeding along the marsh edge.

You look away for only a moment.

When you look back, they’re gone.

They haven’t left the marsh.

Unlike many rabbits people are used to seeing, marsh rabbits are strong swimmers. Water is not simply something they avoid; it is part of the landscape they know how to use. In a place shaped by tides, wet ground, and narrow edges of cover, the ability to move through water helps explain how they can vanish so completely without ever leaving the marsh (Chapman & Trani, 2007; Chapman & Willner, 1981).

The same dense vegetation that feeds them also protects them. Slight changes in elevation, the rhythm of the tides, the angle of the evening sun, and generations of natural selection have shaped an animal that survives by knowing exactly when to be seen — and when not to be (Chapman & Willner, 1981; Holler & Conaway, 1979).

The rabbit disappeared from sight.

Its place in the marsh never did.

Looking at the Marsh Differently

The next time you notice a marsh rabbit quietly feeding along the marsh edge, pause before it disappears.

What once looked like an ordinary rabbit is now something entirely different.

Not because the rabbit has changed.

But because you can now see the countless connections passing through it (Soulé et al., 2003).

And once you see those connections, the marsh becomes harder to overlook.

A marsh rabbit slips back into the edge, leaving only a glimpse of the connections still moving through the marsh. | Image credit: maxnel, iNaturalist

References

Bransford, T. D., Harris, S. A., & Forys, E. A. (2024). Seasonal variation in mammalian Mesopredator spatiotemporal overlap on a barrier island complex. Animals, 14(16), 2431. https://doi.org/10.3390/ani14162431

Canepuccia, A. D., Fanjul, M. S., & Iribarne, O. O. (2023). Global distribution and richness of terrestrial mammals in tidal marshes. Diversity and Distributions, 29(5), 598-612. https://doi.org/10.1111/ddi.13683

Chapman, B. R., & Trani, M. K. (2007). Marsh Rabbit (Sylvilagus palustris). In The Land Manager’s Guide to Mammals of the South (pp. 247-251). Durham, NC: The Nature Conservancy; Atlanta, GA: U.S. Forest Service.

Chapman, J. A., & Willner, G. R. (1981). Sylvilagus palustris. Mammalian Species, (153), 1. https://doi.org/10.2307/3503947

Conner, L. M., & Cherry, M. J. (2017). Considering Herbivory and Predation in Forest Management. In Ecological Restoration and Management of Longleaf Pine Forests (1st ed., p. 12). CRC Press.

Frizzell, E. K. (1988). Mammals and Wetlands. In The Ecology and Management of Wetlands: Volume 1: Ecology of Wetlands (1st ed., pp. 213-226). Croom Helm Ltd.; Timber Press.

Hill, J. E., DeVault, T. L., & Belant, J. L. (2019). Cause‐specific mortality of the world’s terrestrial vertebrates. Global Ecology and Biogeography, 28(5), 680-689. https://doi.org/10.1111/geb.12881

Holler, N. R., & Conaway, C. H. (1979). Reproduction of the marsh rabbit (Sylvilagus palustris) in South Florida. Journal of Mammalogy, 60(4), 769-777. https://doi.org/10.2307/1380192

Jiménez, J., Nuñez-Arjona, J. C., Mougeot, F., Ferreras, P., González, L. M., García-Domínguez, F., Muñoz-Igualada, J., Palacios, M. J., Pla, S., Rueda, C., Villaespesa, F., Nájera, F., Palomares, F., & López-Bao, J. V. (2019). Restoring APEX predators can reduce mesopredator abundances. Biological Conservation, 238, 108234. https://doi.org/10.1016/j.biocon.2019.108234

Larsen-Gray, A. L., Loeb, S. C., & Kalcounis-Rueppell, M. C. (2021). Rodent population and community responses to experimental, large scale, long-term coarse Woody debris manipulations. Forest Ecology and Management, 496, 119427. https://doi.org/10.1016/j.foreco.2021.119427

Macarthur, R., & Levins, R. (1967). The limiting similarity, convergence, and divergence of coexisting species. The American Naturalist, 101(921), 377-385. https://doi.org/10.1086/282505

Rhoads, S. N., & Young, R. T. (1897). Notes on a Collection of Small Mammals from Northeastern North Carolina. Proceedings of the Academy of Natural Sciences of Philadelphia, 49, 303-312. https://www.jstor.org/stable/4062279?seq=1

Soulé, M. E., Estes, J. A., Berger, J., & Del Rio, C. M. (2003). Ecological effectiveness: Conservation goals for interactive species. Conservation Biology, 17(5), 1238-1250. https://doi.org/10.1046/j.1523-1739.2003.01599.x

Suraci, J. P., Clinchy, M., Zanette, L. Y., & Wilmers, C. C. (2019). Fear of humans as APEX predators has landscape‐scale impacts from mountain lions to mice. Ecology Letters, 22(10), 1578-1586. https://doi.org/10.1111/ele.13344

Wigley, T. B., & Lancia, R. A. (1998). Wildlife Communities. In Southern Forested Wetlands (1st ed., p. 32). Routledge.

June 26, 2026
Where the Sand Breathes: Life Beneath the Tide Line in Onslow County

Most beachgoers look across the shoreline and see a boundary.

The ocean ends. The land begins.

But the strip of sand where waves wash ashore and slide back toward the sea is not really either one. It is a threshold—a place that becomes ocean and land again with every passing wave.

At first glance, this narrow band of wet sand appears empty. There are no marsh grasses, no oyster reefs, and no obvious schools of fish. Yet beneath the surface, the sand is alive with animals digging, filtering, feeding, hunting, and breathing.

This is the swash zone: the constantly shifting seam between ocean and land.

It is one of the most overlooked ecosystems on the North Carolina coast.

The swash zone is the narrow strip of shoreline where waves wash ashore and then retreat back toward the sea. Though it may appear to be little more than wet sand, it supports a diverse community of animals adapted to life between ocean and land. | Image credit: J. Morales

The Beach That Never Stops Moving

Unlike a marsh, oyster reef, or seagrass meadow, the swash zone never stays still.

Each wave pushes seawater into the sand and then pulls it back out again. Water moves through the spaces between sand grains, carrying oxygen, microscopic algae, bacteria, and organic matter. The sand itself acts almost like a living filter, supporting communities of organisms adapted to conditions that change minute by minute (Brown & McLachlan, 2018; McLachlan & Defeo, 2018).

To survive here, animals must tolerate burial, shifting sediments, crashing waves, changing salinity, and predators arriving from both land and sea.

Few species can endure such instability.

Those that do are specialists (Defeo et al., 2009).

The Living Wave Riders: Mole Crabs and Coquina Clams

If you’ve ever noticed the wet sand suddenly shimmer or seem to move as a wave retreats, you’ve likely witnessed two of the swash zone’s most abundant residents.

Atlantic Mole Crabs (Emerita talpoida)

An Atlantic mole crab, in Surf City, NC, briefly exposed at the surface of the swash zone. Within seconds, these specialized crustaceans can bury themselves beneath the sand, where they spend most of their lives filtering food from the surf. | Image credit: johnnybirder, iNaturalist

Known locally as sand fleas, Atlantic mole crabs spend nearly their entire lives buried beneath the surface of the swash zone.

They are not true crabs. Instead, they belong to a group of highly specialized crustaceans adapted for life where waves break on the shore. Their bodies are smooth, streamlined, and shaped almost like a small bean. Using powerful rear legs, they can bury themselves in saturated sand in seconds (Abude et al., 2024).

When waves wash overhead, they extend feathery antennae into the water and filter microscopic plankton and organic particles from the surf (Abude et al., 2024).

Rather than remaining stationary, mole crabs occupy the constantly shifting swash zone, where food and oxygen are delivered by breaking waves. Their abundance makes them one of the most important food sources for shorebirds, fish, and ghost crabs (Abude et al., 2024).

Coquina Clams (Donax variabilis)

Sharing the same habitat is one of the most recognizable shells on Atlantic beaches.

Coquina clams are the tiny, brightly colored shells scattered across the tide line in shades of pink, yellow, purple, blue, orange, and white.

Most people only notice the shells.

The living animal beneath them is remarkably adapted to life in moving sand.

Coquinas live just beneath the surface of the swash zone where they filter microscopic algae and suspended particles from the water. As waves advance and retreat, they repeatedly rebury themselves, using a muscular foot to dig into the sand with astonishing speed (Ellers, 1995).

Like mole crabs, coquinas are adapted to the dynamic conditions of the swash zone. Their abundance provides food for fish, crabs, and shorebirds, making them a critical link between microscopic plankton and larger coastal predators (Wilson, 1999).

Standing at the water’s edge, it is easy to think the beach is motionless.

In reality, thousands of coquinas and mole crabs may be moving beneath your feet with every wave.

The Night Shift: Atlantic Ghost Crabs (Ocypode quadrata)

Higher on the beach, above the reach of most waves, another resident waits.

Atlantic ghost crabs spend daylight hours hidden inside deep burrows excavated into the sand. Their pale coloration blends almost perfectly with the beach, making them difficult to see unless they move.

Atlantic ghost crabs spend daylight hours hidden in burrows above the tide line. Their pale coloration provides excellent camouflage against the sand, making them surprisingly difficult to spot until they move. | Image credit: A. Mitchell

While the swash zone below is dominated by animals filtering food from the surf, ghost crabs are hunters and scavengers.

After sunset, they emerge to patrol the shoreline, feeding on mole crabs, coquina clams, stranded marine organisms, insects, carrion, and whatever other opportunities the beach provides (Wolcott, 1978).

Many beachgoers never see them at all. Instead, they notice the evidence they leave behind. Round burrow openings dot the upper beach. Fresh tracks crisscross the sand overnight and disappear with the next tide. Occasionally, a pale shape darts sideways through the beam of a flashlight before vanishing into darkness.

Those burrows tell a story of their own. Beaches with abundant ghost crab burrows often support richer communities of animals living both above and below the sand, which is why scientists sometimes use ghost crabs as one way of assessing beach condition and disturbance (Schlacher et al., 2016).

The next time you notice a round hole in the upper beach with a pile of freshly excavated sand nearby, you are likely looking at the entrance to a ghost crab burrow—and evidence that the beach is still very much alive after dark.

Between the Grains

The largest residents of the swash zone are only part of the story.

Beneath the surface lies an even larger community that most beachgoers never see. Between individual grains of sand are tiny water-filled spaces that form a hidden habitat known as the interstitial zone. To us, a handful of wet sand looks solid. To these organisms, it is an underwater landscape of tunnels, chambers, and passageways (Higgins & Thiel, 1988).

The beach is layered with hidden communities. From amphipods and ghost crabs higher on the shore to coquina clams and mole crabs at the water’s edge, different species occupy distinct zones shaped by waves, moisture, food availability, and shifting sand. | Image credit: Michel et al., 2016

Amphipods: The Cleanup Crew

The line of seaweed, shells, and debris left behind by the tide may look messy, but it is often one of the busiest places on the beach.

Hidden among the wrack, in the upper intertidal zone, are amphipods, small crustaceans often called Atlantic beach hoppers (Americorchestia longicornis). If you sift through a pile of damp seaweed or drift algae, you may catch a glimpse of them springing away before disappearing back into cover.

Much of what washes ashore eventually becomes food for something else. Amphipods feed on decaying seaweed, dead animals, and other organic material stranded by the tide. In doing so, they help break down material that would otherwise accumulate along the shoreline. They also become food themselves, supporting shorebirds, fish, and other invertebrates that forage along the beach (Dugan et al., 2003).

Polychaete Worms: Engineers Beneath the Sand

Most beachgoers never see the worms living beneath the tide line, but their work is happening constantly beneath the surface.

As polychaete worms burrow through the sand, they create tiny pathways that allow water and oxygen to penetrate deeper into the sediment. In many ways, they perform the same role that earthworms do in a garden, except their garden is the beach itself.

Some species spend their lives feeding on organic material trapped between the sand grains, such as Lugworms (Arenicolidae). Others hunt small crustaceans and worms moving through the sediment such as Bloodworms (Glyceridae) and Paddle Worms / Shimmy Worms (Nephtyidae). As they burrow, feed, and move through the beach, they continually mix the sand and help create conditions that allow countless other organisms to survive there (McLachlan & Defeo, 2018).

Ribbon Worms: Hidden Predators

Not every animal beneath the sand is feeding on algae, bacteria, or decaying material.

Ribbon worms (Nemertea) are predators, though few people ever realize they are there. Hidden beneath the surface, they hunt some of the same tiny animals that share the spaces between the sand grains, including small worms, crustaceans, and other invertebrates moving through the sediment (Thiel & Kruse, 2001).

Many possess a remarkable feeding structure called a proboscis that can be rapidly extended to capture prey (Thiel & Kruse, 2001).

Most beachgoers will never see a ribbon worm, yet they are part of the same hidden food web as the amphipods, copepods, and nematodes surrounding them. Even beneath a seemingly empty stretch of sand, animals are feeding, avoiding predators, and competing for resources every hour of the day.

Nematodes: Life at Microscopic Scale

If you could shrink yourself down and explore a handful of wet sand, the landscape would look very different.

What appears solid to us is actually filled with tiny spaces between the grains. Moving through those water-filled passages are microscopic animals called nematodes (phylum Nematoda).

These tiny roundworms feed on bacteria, algae, fungi, and organic matter coating the sand. Though nearly invisible, they are among the most abundant animals on many beaches and play an important role in breaking down organic material and recycling nutrients throughout the sediment (Coull, 1999; Schratzberger & Ingels, 2018).

Harpacticoid Copepods: Tiny Links in the Food Web

Sharing those same microscopic spaces are harpacticoid copepods (Paraleptastacus wilsoni), tiny crustaceans that spend their lives moving between individual sand grains.

They graze on algae and microbial films coating the sediment, feeding on resources too small for larger animals to use directly. In turn, they become prey for larger invertebrates and juvenile fishes.

Most beachgoers will never see a harpacticoid copepod. Yet every handful of wet sand may contain a community of animals like these, quietly connecting the microscopic world to the larger food web of the beach (Schratzberger & Ingels, 2018).

Individually, these animals are easy to overlook.

Collectively, they form much of the living foundation of the tide line. The coquinas, mole crabs, ghost crabs, fishes, and shorebirds visible along the shoreline all depend, directly or indirectly, on countless small interactions taking place beneath the sand.

Following the Birds

One of the easiest ways to observe this hidden ecosystem is not by looking down.

It is by looking up.Anyone who spends time on the beach has likely watched sanderlings (Calidris alba) racing along the edge of the surf. They dart forward as a wave retreats, stop suddenly to probe the sand, and then sprint away from the next incoming wave. A little farther up the beach, ruddy turnstones (Arenaria interpres) pick through wrack lines left behind by the tide. Along the surf edge, Eastern willets (Tringa semipalmata semipalmata) walk deliberately through the shallows, searching for movement beneath the water.

To many beachgoers, they are simply birds feeding along the shoreline.

What they are actually doing is reading the beach.

Each probe into the sand is a search for prey hidden beneath the surface. Mole crabs, small worms, amphipods, coquinas, and other invertebrates living within the tide line provide food for these birds (Dugan et al., 2003; Hubbard & Dugan, 2003).

The birds go where the food is.

When shorebirds gather along a stretch of beach, they are often revealing an ecosystem that would otherwise remain invisible. Their presence tells us that the sand beneath them is alive with prey, even if we cannot see it ourselves.

In many ways, shorebirds act as interpreters of the tide line. By watching where they feed, pause, and congregate, we gain a glimpse into the hidden community supporting them below.

Reading the Beach

From a distance, the tide line can seem almost empty. A narrow strip of wet sand separates the ocean from the rest of the beach. Waves arrive, waves leave, and little appears to change.

Spend a few minutes watching, however, and a different picture begins to emerge.

Shorebirds gather where the surf is most active. Tiny shells appear and disappear with the retreating waves. Fresh ghost crab burrows punctuate the upper beach. Even the wrack line left behind by the tide becomes a gathering place for scavengers and foraging birds.

What first appears to be a simple boundary between land and sea begins to look more like a busy shoreline neighborhood.

At first glance, the tide line can appear almost empty. Look a little longer, however, and the clues begin to emerge—feeding shorebirds, scattered shells, and the constant movement of the surf all hint at the hidden community living beneath the sand. | Image credit: A. Mitchell

The animals living here are responding to the same thing: the constant movement of the tide. Food arrives with the surf, becomes available for a brief moment, and is quickly claimed by whatever creature is best adapted to find it. Some filter it from the water. Some collect it from the sand. Others hunt the animals already feeding there.

Because these organisms live so closely tied to the conditions of the beach, changes in their numbers can provide clues about the habitat itself (Defeo et al., 2009). A shoreline where birds are feeding, ghost crab burrows remain active, and life continues to reveal itself at the edge of the surf is often a sign that this narrow strip of beach is supporting the community that depends upon it.

When those communities decline, the change may not be immediately obvious. Yet over time the beach can begin to feel quieter. Fewer birds stop to feed. Fewer burrows appear in the sand. The signs become harder to find. Those changes can ripple outward through the food web, affecting species both on the beach and beyond it (Peterson et al., 2006).

The Threshold

The next time you stand at the edge of the surf, watch where the waves pause before sliding back toward the sea.

It is easy to see this narrow strip of shoreline as a boundary. Ocean on one side. Land on the other.

But the tide line is not really a dividing line at all.

It is a place where both worlds meet.

With every passing wave, food, oxygen, and life arrive from the ocean. Beneath the sand, animals capture it, consume it, recycle it, and pass it on. Shorebirds search for it. Ghost crabs emerge after dark to hunt it. Countless organisms spend their entire lives within a space that is neither fully ocean nor fully land.

Most people walk across this strip of beach without ever noticing it.

Yet it is one of the busiest places along the coast.

The next time you see shells appearing and disappearing in the surf, a flock of sanderlings racing the tide, or ghost crab burrows scattered across the upper beach, remember that these are not separate observations. They are pieces of the same story.

What appears to be an empty stretch of wet sand is actually a living threshold—a place where ocean and land remain connected through countless interactions happening beneath every step.

And once you see it, it becomes difficult to look at the shoreline the same way again.

The tide line in Surf City, NC may appear to be little more than wet sand. Yet beneath every retreating wave lies a hidden community connecting ocean and land through countless interactions, most of them unseen. | Image credit: A. Mitchell

References

Abude, R. R., Lôbo-Hajdu, G., Moreira, D. A., & Cabrini, T. M. (2024). Sandy beach mole crabs (Decapoda: Hippidae: Emerita): A systematic review of the anthropic impacts, populations density, and conservation strategies. Marine Environmental Research, 202, 106745. https://doi.org/10.1016/j.marenvres.2024.106745

Coull, B. C. (1999). Role of meiofauna in estuarine soft‐bottom habitats. Australian Journal of Ecology, 24(4), 327-343. https://doi.org/10.1046/j.1442-9993.1999.00979.x

Defeo, O., McLachlan, A., Schoeman, D. S., Schlacher, T. A., Dugan, J., Jones, A., Lastra, M., & Scapini, F. (2009). Threats to sandy beach ecosystems: A review. Estuarine, Coastal and Shelf Science, 81(1), 1-12. https://doi.org/10.1016/j.ecss.2008.09.022

Dugan, J. E., Hubbard, D. M., McCrary, M. D., & Pierson, M. O. (2003). The response of macrofauna communities and shorebirds to macrophyte wrack subsidies on exposed sandy beaches of Southern California. Estuarine, Coastal and Shelf Science, 58, 25-40. https://doi.org/10.1016/s0272-7714(03)00045-3

Ellers, O. (1995). Behavioral control of swash-riding in the clam Donax variabilis. The Biological Bulletin, 189(2), 120-127. https://doi.org/10.2307/1542462

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June 5, 2026
When the Water Turns Gelatinous: The Hidden Filter Feeders of Onslow County

Sometimes the estuary changes before people notice why.

The water may look normal from shore, but drifting just beneath the surface are long ribbons of translucent gelatin — soft strands that gather along marsh edges, collect in eddies, or drift through the current like mucus suspended in the tide. In Surf City this week, people described them as “whale snot.”

Gelatinous material collected from Murrells Inlet, South Carolina at the low tide edge. Such suspended material may include colonial tunicates, salps, mucus-rich plankton aggregates, and other organic matter associated with productive estuarine conditions. | Image credit: J. Mattevi

They are more likely colonial tunicates or salps, gelatinous filter-feeders that can appear suddenly when conditions in the water favor rapid plankton growth (Bone, 1998; Madin & Deibel, 1998).

What matters is not only the organisms themselves, but what their appearance says about the estuary around them.

The drifting forms

These blooms often form when the water column becomes temporarily stable and productive (Madin, 1982). Warmer temperatures, calmer conditions, reduced wave turbulence, and elevated plankton concentrations create an environment where filter-feeding gelatinous organisms can reproduce rapidly. Water moving through the inlets may also transport offshore plankton communities into the estuary, concentrating them in tidal creeks and slower-moving surface water (Bone, 1998; Madin, 1982).

In these calmer stretches, the water column begins separating into layers. Suspended plankton remains concentrated near the surface while weaker turbulence allows fragile gelatinous colonies to persist long enough for blooms to form. What would normally disperse through wave action instead remains suspended within the estuary itself (Madin, 1982).

To most people, they look like debris.

Ecologically, they are processing the estuary in real time.

Salps and colonial tunicates continuously pump water through their bodies, removing suspended phytoplankton, bacteria, and organic particles from the water column. During bloom periods, enormous volumes of water can be filtered each day (Madin, 1982; Sutherland et al., 2010). In effect, the estuary briefly develops a drifting layer of living filtration suspended between the surface and the bottom.

Each colony filters continuously. Thousands moving through a tidal creek or marsh edge at once can collectively filter enormous volumes of suspended material over short periods of time, temporarily altering the clarity and composition of the surrounding water (Riisgård & Larsen, 2010).

That shift affects everything around them.

When these blooms are abundant, water clarity can temporarily improve as suspended particles are removed. Organic material becomes concentrated into mucus-rich waste pellets and decaying gelatinous tissue that sink toward the bottom, transferring energy from the surface into benthic food webs below (Madin & Deibel, 1998). Microbes, worms, crustaceans, and scavengers begin responding almost immediately (Madin, 1982; Madin & Deibel, 1998).

Instead of remaining suspended near the surface, nutrients and organic matter begin settling downward through the water column. What had been dispersed through open water becomes concentrated along the bottom, where deposit-feeding worms, small crustaceans, microbes, and scavengers begin incorporating that material into the estuary below (Madin, 1982).

The bloom itself becomes food.

The drifting masses also create temporary structure within otherwise open water. Small fish gather along their edges. Tiny invertebrates gather within folds and strands of gelatinous tissue. Predators begin responding not only to the bloom itself, but to the concentration of life forming around it (Bone, 1998; Madin & Deibel, 1998).

Small fish and invertebrates feed around the edges of these drifting masses. Juvenile fishes may remain near these drifting masses as food becomes concentrated around them. Sea turtles, some fishes, and other gelatinous predators may increase feeding activity where blooms become dense enough to concentrate prey (Bone, 1998).

But like many ecological events, balance matters.

If too few filter-feeders are present during periods of elevated nutrients, water grows murkier and oxygen conditions become less stable, particularly during heat and nighttime respiration. But filtration at the opposite extreme can also reshape the food web. Too many gelatinous filter-feeders, however, may strip large amounts of plankton from the water column, altering food availability for larval fishes and other plankton-dependent organisms higher in the food web (Petersen & Riisgård, 1992).

Most blooms are temporary.

Currents disperse them. Heat and bacteria break them apart. Waves fragment the colonies into nearly invisible strands that disappear back into the system as quickly as they arrived. Even in collapse, the bloom continues feeding the estuary. Decaying tissue is broken apart by bacteria, consumed by scavengers, and recycled back into the same nutrient pathways that allowed the bloom to form in the first place (Madin, 1982).

But for a short period, the estuary reveals something normally hidden: the water between the marsh and the bottom is not empty space. It is an active habitat, filled with organisms that filter, recycle, transport, and redistribute energy through the coastal ecosystem (Bone, 1998; Madin, 1982).

The attached forms

Not all tunicates remain suspended in the water column. Some attach themselves directly to the surfaces that hold still long enough for life to accumulate—dock pilings, oyster shell, ropes, marsh grass roots, floats, and the shaded undersides of piers where current continues moving but turbulence drops away.

Along the estuaries of Onslow County, these attached forms become part of what looks, at first glance, like simple buildup.

The surfaces beneath docks rarely stay bare for long (Wahl, 1989; Lindeyer & Gittenberger, 2011). Marine scientists often describe these layered growths as fouling communities, but along the estuary they appear simply as the layer of life that forms on anything left in the water long enough. First comes a film too thin to notice, then algae, then colonies of organisms layered over one another until wood, shell, and rope begin carrying part of the estuary itself.

Sea squirts and other attached filter-feeders beneath a dock in Surf City, North Carolina. | Image credit: A. Mitchell

Tunicates are part of that layer.

Along this coast, attached tunicates can include solitary species like the pleated sea squirt (Styela plicata) and the sea grape (Molgula manhattensis), as well as colonial species such as Clavelina oblonga and sea pork (Aplidium stellatum) (Van Name, 1945; Lambert, 2007).

Some grow individually, attached like soft sacs with openings at the top. Others spread as colonial sheets or clustered lobes, sharing a common outer covering while continuously filtering water moving past them. Around pilings and floating docks, entire communities can form this way—sponges beside hydroids, bryozoans layered against tunicates, all responding to current, salinity, temperature, and suspended food moving through the tide (Wahl, 1989).

To most people, these surfaces register as slime.

Ecologically, they are filtration, habitat, and nutrient transfer occurring simultaneously (Wahl, 1989).

Sea squirts

The organisms most people recognize first are usually sea squirts. They appear as rubbery sacs attached beneath docks or clustered along ropes, and shell. Press one accidentally and water jets outward through small siphons near the top of the body, giving rise to the common name.

A sea squirt partially coated in algae and sediment beneath shallow estuarine water in Surf City, North Carolina. The two siphon openings are part of the continuous filtration process occurring beneath docks and marsh edges. | Image credit: A. Mitchell

Species such as the pleated sea squirt (Styela plicata) often develop thick, wrinkled outer coverings ranging from tan and off-white to purple, while the sea grape (Molgula manhattensis) forms smaller rounded bodies attached within the layered communities growing beneath docks and along estuarine structure — what marine scientists often call fouling communities (Van Name, 1945).

What looks like a reaction is actually the visible end of a process already underway.

Sea squirts continuously pull water inward through one siphon, filter out phytoplankton, bacteria, and suspended particles from the water, then expel the filtered water back into the estuary through another opening. The animal does not begin filtering when disturbed. It has been filtering the entire time (Riisgård & Larsen, 2010).

In productive estuarine water, thousands of these organisms may be pumping simultaneously (Riisgård & Larsen, 2010).

That filtration matters.

As suspended particles are removed, nutrients become concentrated into waste and biomass that can be transferred downward into bottom communities. Water clarity may improve locally (Riisgård & Larsen, 2010). Microbial activity shifts around them. Small invertebrates begin using the folds and surfaces their bodies create.

Their presence also signals something about the surrounding water.

Sea squirts tend to cluster where flow remains steady enough to deliver oxygen and suspended food continuously, but not so violent that colonies are torn free. Around tidal creeks, dock edges, and quieter stretches of the Intracoastal Waterway, their abundance often reflects a system carrying enough suspended productivity to sustain constant filtration (Barros, 2009).

Sea pork

Some tunicates take a different form entirely.

One of these is sea pork, commonly associated with colonial tunicates such as Aplidium stellatum, which spread outward as shared gelatinous colonies rather than isolated individuals (Van Name, 1945).

Sea pork, a colonial tunicate, washed ashore along Surf City, North Carolina. Though it appears as a single gelatinous mass, it is made up of thousands of tiny filter-feeding animals embedded within a shared outer layer. | Image credit: D. Miles

Sea pork spreads across submerged surfaces in thick, rubbery colonies that look less like individual animals and more like flesh-colored mats attached beneath floats and pilings. Depending on the species and age of the colony, the surface may appear muted pink, tan, orange, or almost translucent beneath the waterline.

Most people don’t realize they are looking at colonies made up of thousands of tiny individual filter-feeding bodies embedded together within a shared outer layer.

The colony functions collectively (Van Name, 1945).

Water moves continuously through countless small openings across the surface, carrying suspended plankton and organic particles into the colony while waste and filtered water move back outward into the surrounding estuary (Riisgård & Larsen, 2010).

That structure changes the surface around it.

Sea pork colonies trap sediment and create small protected surfaces where microorganisms and invertebrates begin to accumulate between folds and protected edges. Tiny crustaceans move across them. Worms and microbial films develop within the folds and protected spaces between colonies. What appears smooth from above becomes, at smaller scales, complex terrain (Wahl, 1989).

Like other filter-feeding communities along this coast, sea pork helps transfer suspended energy from the water column into the attached world beneath docks and marsh edges.

And once that layered habitat forms, other organisms begin responding to it—including the nudibranchs moving slowly across its surface.

Nudibranchs

At low tide along the edges of the sound—where pilings hold a thin skin of life and oyster shells stack into uneven ridges—the water sometimes carries color that doesn’t belong to the sand or the grass. It moves slowly, almost deliberately, across surfaces that most people step over without noticing. What looks like a fragment of drifting algae or a soft piece of shell resolves, if you stop long enough, into something alive.

These are nudibranchs.

They are not fish, not worms, not plants. They are marine gastropods—relatives of snails—but without shells (Valdés et al., 2006). Along the coast of Onslow County, they appear in the quiet places: beneath docks in the Intracoastal Waterway, along the edges of Topsail Island marsh creeks, and on the submerged surfaces where current slows just enough for growth to take hold.

Along shallow estuarine structure in this region—beneath docks, across pilings, and within the layered growth attached to ropes and shell—nudibranchs may include species such as the striped nudibranch (Cratena pilata), the Brazilian aeolid sea slug (Spurilla braziliana), the fringeback dondice (Dondice occidentalis), Thecacera pennigera, Berghia rissodominguezi, and the brackish-water species Tenellia adspersa (Marcus, 1972; Valdés et al., 2006).

Most people never see them. But they are there, working through the same system that shapes everything else along this coast.

A nudibranch collected near Morehead City, North Carolina, viewed under magnification. The cerata along its back increase surface area for respiration and, in some species, store defensive stinging cells obtained from prey. | Image credit: marineinvertgirl, iNaturalist

Built for sensing, not speed

A nudibranch’s body is built for sensing and feeding, not speed. The two structures at the front—rhinophores—sample the water chemically, reading it the way a shoreline bird reads the wind. Along their backs, many species carry cerata, small extensions that look ornamental but function as both respiration and defense.

In aeolid nudibranchs like Spurilla braziliana, Cratena pilata, and Berghia rissodominguezi, these cerata become important sites for both respiration and defensive storage of stinging cells obtained from prey (Goodheart et al., 2018).

The Brazilian aeolid sea slug (Spurilla braziliana) moving across submerged structure near Morehead City, North Carolina. The cerata lining its back function in respiration and can store defensive stinging cells obtained from prey such as anemones and hydroids. | Image credit: wonglab, iNaturalist

They move slowly because they can afford to. Their food doesn’t run.

Sponges, hydroids, bryozoans—these are the surfaces most people would describe as “growth” on docks or shells. To a nudibranch, those surfaces are structure, habitat, and food all at once (Valdés et al., 2006).

The work they do (even when no one’s watching)

Along this coastline, growth is constant. Give any hard surface—an old piling, a piece of shell, a boat hull—enough time in the water and it becomes layered. First a film, then algae, then invertebrates. The system builds upward and outward, creating what scientists call structural complexity, but what you actually see is texture: roughness where there used to be smoothness (Wahl, 1989).

Along shallow estuarine bottoms, algae, shell, and attached growth begin forming the layered habitat that supports juvenile fish, crabs, filter-feeders, and the organisms moving through the estuary food web. | Image credit: A. Mitchell

Nudibranchs move through that texture selectively.

Many species feed on a single type of prey. One may specialize in a particular sponge. Another tracks hydroids, those delicate branching animals that resemble tiny underwater ferns. Species such as Dondice occidentalis, Cratena pilata, and Tenellia adspersa are commonly associated with hydroids and other organisms growing across submerged pilings, docks, ropes and shell in shallow coastal environments (Marcus, 1972; Valdés et al., 2006). This selectivity matters more than their size suggests. They are not removing everything. They are removing specific pieces of the system.

That kind of feeding does not flatten the landscape—it shapes it.

Where one organism begins to dominate, nudibranchs can limit its spread. Where surfaces would otherwise become uniform, their grazing introduces variation. Over time, this helps maintain the uneven habitat small fish, shrimp, and juvenile invertebrates depend on (Wahl, 1989).

Growth that begins as algae quickly becomes habitat. Along shallow estuarine edges, layered vegetation and attached organisms create shelter for crabs, juvenile fish, shrimp, and other small life moving through the system. | Image credit: A. Mitchell

It’s easy to miss because nothing dramatic happens. There’s no visible clearing, no sudden absence. But the balance of what grows, and where, shifts quietly in response to their presence.

Borrowed defenses, redistributed energy

Some nudibranchs do something that seems improbable until you see it up close: they take the defenses of what they eat and keep them.

Hydroids and certain cnidarians carry stinging cells—nematocysts—that function as protection. When a nudibranch feeds on them, those cells pass through the digestive system intact and are stored within the cerata along its back. The nudibranch doesn’t just consume its prey; it incorporates part of its defense (Goodheart et al., 2018).

This changes how energy moves through the system.

Instead of defenses being lost when prey is consumed, they are transferred upward. The nudibranch becomes both grazer and deterrent, a small organism that is less likely to be eaten because of what it has already eaten.

You can see the result in their coloration. Many are bright, almost out of place against the muted tones of sand and shell. That color is not decoration—it’s a signal (Avila, 1995). Along this coast, where predation pressure is constant, visibility can function as warning rather than risk.

Where they sit in the trophic cascade

They are not apex predators. They don’t regulate fish populations or move through the system in ways that draw attention. But they occupy a position that connects the base of the food web to everything above it.

They feed on organisms that build habitat.

Those organisms—sponges, hydroids, bryozoans—form the living surface that supports small invertebrates and juvenile fish. Those smaller organisms, in turn, become prey for larger fish, which then connect to the predators people are more familiar with along this coast—species like blacktip shark (Carcharhinus limbatus) and Atlantic sharpnose shark (Rhizopriodion terranovae) that move along the breakers and through the sounds.

Remove the visible predators, and people notice quickly.

Remove something like a nudibranch, and what changes is slower, but it moves in the same direction. Surfaces become dominated by fewer species. Habitat becomes more uniform. The small organisms that rely on variation lose space. That change works its way upward, not as a single event, but as a shift in the system’s capacity to support diversity.

Even small organisms attached to pilings and submerged structure become part of much larger coastal food webs. Scientific food-web models show nudibranchs, hydroids, bryozoans, worms, shrimp, and fishes linked together through the transfer of energy across the ecosystem.

Generalized food web showing how organisms associated with sponge and attached invertebrate communities connect upward through coastal ecosystems. Nudibranchs, hydroids, bryozoans, worms, shrimp, and fishes all participate in the transfer of energy through these layered habitats. Adapted from Archer et al. (2020).

Why they stay hidden

There’s a reason most beachgoers never encounter them.

They live where water movement slows just enough to allow growth to accumulate, but not so still that oxygen drops away. Around docks, inside creeks, along the quieter edges of the New River estuary, they remain attached to the surfaces that feed them.

Out in the open surf, where sand shifts constantly and hard structure is buried and exposed with each change in wind and tide, there’s less for them to hold onto and less for them to eat. The breakers are a moving environment (Wahl, 1989). Nudibranchs belong to the places that hold still just long enough for complexity to form.

What changes if they’re gone

Nothing you would notice in a single afternoon at the beach.

But over time, the surfaces beneath the waterline would begin to simplify. One or two fast-growing organisms would spread further, covering space that would otherwise remain shared. The small sheltered spaces used by larval fish, juvenile shrimp, and small crabs would begin to thin out.

That loss doesn’t stay at the bottom.

It moves upward, changing how much life the system can support, and how evenly that life is distributed. By the time it reaches the fish people see from the shore, the cause is no longer visible. But it started here, in the slow movement of something small across a surface most people never look at twice.

Nudibranchs don’t reshape the coastline in ways that draw attention. They don’t mark their presence with absence or disturbance. Instead, they work within what’s already there—adjusting, redistributing, and maintaining the uneven structure that makes this coast function.

If you happen to see one, it won’t be moving fast. It won’t need to.

What they’re feeding on (and why it looks familiar)

Along the docks and pilings of Onslow County, the surfaces most people notice first aren’t fish at all. They’re the things attached to everything.

The branching, plant-like fuzz that brushes your hand when you reach into the water—those are hydroids. The firm, uneven coatings that look like they’re part of the structure itself are often sponges or bryozoans.

It’s easy to group all of it together as buildup. Something slimy, something in the way.

But that “squirt” people laugh about isn’t random. A tunicate pulls water in, filters out plankton and suspended particles, and then expels that water back out. What looks like a reaction is just the visible end of constant filtration. They are processing the water column—removing particles, cycling nutrients, and clarifying the water in small, continuous ways (Riisgård & Larsen, 2010).

Hydroids are doing something different. They are predators at a scale most people don’t consider, capturing microscopic prey drifting past. Sponges filter continuously as well, pulling bacteria and organic matter from the water and converting it into biomass that other organisms can use.

A sea anemone beneath shallow estuarine water in Surf City, North Carolina. Organisms like these become part of the layered communities that nudibranchs, tunicates, hydroids, and other invertebrates move through beneath the surface. | Image credit: A. Mitchell

This is the surface layer of the ecosystem.
And it doesn’t stay unchecked.

The ones moving across the surface

Species like the Brazilian aeolid sea slug (Spurilla braziliana) often feed directly on anemones associated with these same submerged communities, while smaller species such as Tenellia adspersa are frequently associated with hydroids in brackish and estuarine waters (Valdés et al., 2006).

The nudibranchs moving across these surfaces are not all the same, and what they eat tells you what role they’re playing.

Some of the small, leaf-like sea slugs in this region—species in the genus Elysia—feed on algae and can even retain the chloroplasts from what they consume, briefly using sunlight as part of their energy system. They blur the line between grazing and something closer to plant-like function (Valdés et al., 2006).

Others, like Cratena pilata and Dondice occidentalis, track hydroids specifically. Where hydroids begin to spread across a piling, these nudibranchs follow, feeding in a way that limits how dense those colonies can become (Marcus, 1972).

Species such as Thecacera pennigera are often associated with the layered communities growing beneath docks and harbor structure, while Berghia rissodominguezi and Spurilla braziliana move through shallow cnidarian-rich habitat where anemones and hydroids provide both food and defensive material (Valdés et al., 2006).

Heavier-bodied nudibranchs—often in groups like Doris—tend to feed on sponges. Not all sponges, and not everywhere, but selectively enough that no single form easily dominates a surface for long.

Even their eggs reflect this connection. The ribbon-like spirals sometimes seen attached to docks are laid directly where food is available. The next generation doesn’t disperse randomly—it begins where the system is already functioning.

Beneath the surface layer

Most of the time, these organisms go unnoticed.

People see the drifting ribbons and call them whale snot. They scrape tunicates from pilings without thinking about what those colonies were filtering from the water. They brush past hydroids and sponges growing beneath docks without realizing those surfaces are part of the estuary’s food web just as much as the fish moving above them.

But the water between the marsh and the bottom is never empty.

It carries suspended plankton, drifting larvae, dissolved nutrients, bacteria, predators, scavengers, and colonies of organisms filtering continuously through the tide. Along the quieter edges of Onslow County—beneath floats, around oyster shells, beside marsh grass roots, and inside the slower water of creeks and sounds—entire communities form within that suspended layer (Wahl, 1989; Lindeyer & Gittenberger, 2011).

Some drift. Some attach. Some graze slowly across the surface consuming the organisms beneath them.

Together, they reshape the estuary constantly.

The gelatinous ribbons appearing this week are not separate from the rest of the system. They are one visible moment in a larger cycle of filtration, growth, decay, grazing, and redistribution that normally happens out of sight (Bone, 1998; Madin, 1982). For a short time, the estuary simply becomes easier to see.

What appears empty from above often contains layered communities of algae, filter-feeders, invertebrates, and microorganisms quietly redistributing energy through the estuary. Surf City, North Carolina. | Image credit: A. Mitchell

References

Avila, C. (1995). Natural products of opisthobranch molluscs: A biological review. In Oceanography and marine biology: An annual review (33rd ed., pp. 487-559). UCL Press.

Barros, R. (2009). Human-mediated global dispersion of Styela plicata (Tunicata, Ascidiacea). Aquatic Invasions, 4(1), 45-57. https://doi.org/10.3391/ai.2009.4.1.4

Bone, Q. (1998). The biology of pelagic tunicates. Oxford University Press on Demand.

Encarnação, J., Seyer, T., Teodósio, M. A., & Leitão, F. (2020). First record of the nudibranch Tenellia adspersa (Nordmann, 1845) in Portugal, associated with the invasive hydrozoan Cordylophora caspia (Pallas, 1771). Diversity, 12(6), 214. https://doi.org/10.3390/d12060214

Goodheart, J. A., Bleidißel, S., Schillo, D., Strong, E. E., Ayres, D. L., Preisfeld, A., Collins, A. G., Cummings, M. P., & Wägele, H. (2018). Comparative morphology and evolution of the cnidosac in Cladobranchia (Gastropoda: Heterobranchia: Nudibranchia). Frontiers in Zoology, 15(1). https://doi.org/10.1186/s12983-018-0289-2

Korshunova, T., Lundin, K., Malmberg, K., Picton, B., & Martynov, A. (2018). First true brackish-water nudibranch mollusc provides new insights for phylogeny and biogeography and reveals paedomorphosis-driven evolution. PLOS ONE, 13(3), e0192177. https://doi.org/10.1371/journal.pone.0192177

Lambert, G. (2007). Invasive sea squirts: A growing global problem. Journal of Experimental Marine Biology and Ecology, 342(1), 3-4. https://doi.org/10.1016/j.jembe.2006.10.009

Lindeyer, F., & Gittenberger, A. (2011). Ascidians in the succession of marine fouling communities. Aquatic Invasions, 6(4), 421-434. https://doi.org/10.3391/ai.2011.6.4.07

Madin, L. P. (1982). Production, composition and sedimentation of salp fecal pellets in oceanic waters. Marine Biology, 67(1), 39-45. https://doi.org/10.1007/bf00397092

Madin, L. P., & Deibel, D. (1998). Feeding and energetics of Thaliacea. The Biology of Pelagic Tunicates, 81-104. https://doi.org/10.1093/oso/9780198540243.003.0005

Marcus, E. D. (1972). On Some Opisthobranchs from Florida. Bulletin of Marine Science, 22(2), 284-308. https://www.ingentaconnect.com/content/umrsmas/bullmar/1972/00000022/00000002/art00002

Petersen, J., & Riisgard, H. (1992). Filtration capacity of the ascidian Ciona intestinalis and its grazing impact in a shallow fjord. Marine Ecology Progress Series, 88, 9-17. https://doi.org/10.3354/meps088009

Riisgård, H., & Larsen, P. (2010). Particle capture mechanisms in suspension-feeding invertebrates. Marine Ecology Progress Series, 418, 255-293. https://doi.org/10.3354/meps08755

Sutherland, K. R., Madin, L. P., & Stocker, R. (2010). Filtration of submicrometer particles by pelagic tunicates. Proceedings of the National Academy of Sciences, 107(34), 15129-15134. https://doi.org/10.1073/pnas.1003599107

Valdés, Á., Behrens, D. W., & DuPont, A. (2006). Caribbean Sea slugs: A Field guide to the opisthobranch mollusks from the tropical Nortwestern Atlantic. Sea Challengers Natural History Books.

Van Name, W. G. (1945). The North and South American Ascidians. Bulletin of American Museum of Natural History, 84, 1-476. http://hdl.handle.net/2246/1186

Wahl, M. (1989). Marine epibiosis. I. Fouling and antifouling: Some basic aspects. Marine Ecology Progress Series, 58, 175-189. https://doi.org/10.3354/meps058175

May 16, 2026
Where Wings Meet Water: Reading Birds Along the Edges of Onslow County

At the Line Where Air Meets Water

On a late spring morning along Surf City, the first movement is often above the water, not within it. Brown pelicans travel low and steady just beyond the breakers, their wingtips nearly touching the surface as they follow a line that seems invisible from shore. Farther out, a group of terns holds in place against the wind, hovering, adjusting, then dropping sharply into the water before rising again. Closer to the sound side of Topsail Island, an osprey circles once, then folds into a dive toward a channel edge that looks, at first glance, no different than the water around it.

Nothing about these movements is random. They are responses to structure that exists beneath the surface—structure shaped by tide, wind, and the movement of other organisms. What appears as scattered bird activity is, in practice, a map of where the water is concentrating life.

For someone standing at the edge of it, that movement is one of the most accessible ways to read what cannot be seen directly.

What Birds Are Following Beneath the Surface

The birds that move along this stretch of coast are not searching broadly; they are tracking concentration. Along barrier island systems like those in Onslow County, physical processes—tidal exchange through inlets, wind-driven surface currents, and subtle differences in bottom shape—create zones where small fish, shrimp, and other prey accumulate (Peterson & Peterson, 1979; Piersma, 1997).

When the tide moves through places like New River Inlet, water does not flow evenly across the landscape. It accelerates through constrictions, slows along marsh edges, and bends around sandbars and channels. These shifts in speed and direction compress organisms into tighter spaces, particularly along boundaries where moving water meets something that resists it—an edge, a drop-off, or a change in depth (Wright et al., 1985).

Small schooling fish respond to that compression by tightening their formation. In doing so, they become more visible and more vulnerable. Larger fish—bluefish, Spanish mackerel, and juvenile coastal sharks—often move in from below, using that same concentration to feed. The pressure from below pushes prey upward, sometimes all the way to the surface.

Coastal birds feeding where prey has been concentrated near the surface along the breakers. | Image credit: A. Mitchell

What appears overhead depends on which part of that concentration each species is built to exploit.

Terns hovering and diving are often responding to prey that has been driven upward by predatory fish (Safina & Burger, 1985). Brown pelicans, which rely on plunge-diving, tend to follow more stable schools of fish that remain near the surface for longer periods (Shields, 2014). Ospreys, in contrast, depend on clear water and individual fish they can visually isolate, which is why their activity often aligns with calmer conditions and defined channel edges (Poole et al., 2002).

Each species is not simply feeding in the same place; each is reading a different layer of the same system.

When Surface Activity Signals Pressure Below

From the shoreline, bird activity can appear as isolated events—one dive, then another, then a sudden shift down the beach. Watched over time, a pattern emerges. A cluster of terns may concentrate in one location for several minutes, then disperse abruptly, reforming farther along the shoreline. Pelicans may align along a narrow band just beyond the breakers, following it as it drifts.

These shifts often reflect changes in how prey is being compressed and released beneath the surface. When predatory fish move through a bait school, the school tightens, rises, and becomes briefly accessible from above. When that pressure dissipates, the school spreads out again, and the birds move on.

This movement of energy—from smaller organisms to larger predators, and upward through the water column—is one visible expression of a trophic cascade. The term itself is often used to describe longer chains of ecological influence, but along the coast it can be observed in compressed moments, where the effects of predation become visible within seconds (Heithaus et al., 2008).

Birds do not initiate this process. They respond to it. Their presence marks where the system has already intensified.

Indicator Species at the Water’s Edge

From the beach, the difference is subtle. The water does not change color dramatically, and the waves continue to break as they did before. The level of activity shifts within that band—first visible in the air, then inferred below– marking places where the system has tightened, energy is moving through multiple layers at once, and the distance between surface and depth has, for a time, narrowed (Heithaus et al., 2008; Estes et al., 2011).

For someone entering the water, these differences in bird behavior can offer practical information, not in a predictive or absolute sense, but as indicators of what is happening just below the surface.

Brown pelicans traveling low in a consistent line often indicate schools of fish moving parallel to shore. Terns repeatedly diving in a tight area suggest smaller prey being pushed upward, frequently by larger fish feeding below. Ospreys focusing on a specific channel edge reflect clearer water and individual prey availability, rather than broad schooling events. Along the shoreline, shorebirds probing the sand at low tide are responding to invertebrates exposed by receding water, signaling a different layer of the system entirely—one tied to sediment and tidal timing rather than active predation (Colwell, 2010; Piersma, 1997).

None of these signals point directly to a specific species beneath the surface. What they indicate is concentration, and concentration is what draws larger predators closer to shore.

Along the coast of North Carolina, nearshore and juvenile shark presence is often associated with areas of high prey density, particularly where schooling fish aggregate (Heupel & Hueter, 2002). These conditions are not constant, and they shift with tide, temperature, and time of day. Birds make those shifts visible in real time.

At times, that activity stretches into lines that run the length of the breakers.

For someone stepping into the water, that narrowing matters. Not as a warning in the abstract, but as a recognition that the conditions supporting visible feeding above often extend below, linking organisms that are rarely seen together into the same moving structure.

Where the System Tightens

The patterns become easier to see near places where the water is forced to narrow, turn, or accelerate. The most consistent bird activity along this coast tends to occur where water movement is constrained and redirected. Inlets, marsh edges, sandbars, and the transitions between the Intracoastal Waterway and adjacent sounds create these zones (Wright et al., 1985).

At New River and its inlet, tidal flow compresses water into narrow channels before releasing it into broader areas, creating gradients in speed and depth. Along these gradients, prey accumulates, predators follow, and birds gather above.

These are not fixed points. As tide rises and falls, and as wind reshapes surface conditions, the locations of these compression zones shift. The birds move with them, tracing patterns that are constantly changing but not random.

For someone watching from shore, these movements can be read as lines, clusters, and absences—places where activity intensifies, and places where it suddenly drops away.

Standing Within It

Entering the water along this coast means stepping into a system already in motion. The surface may appear uniform, but the activity above it often reveals where that motion is focused.

Birds diving repeatedly in a confined area, or tracking a narrow band just beyond the breakers, indicate where prey is concentrated. Those same conditions are what draw larger predators into closer proximity to shore, not as an anomaly, but as part of the same process.

Watching the birds does not eliminate risk, and it does not provide certainty about what is beneath the surface. What it offers is context—a way to recognize when the water is more active, more compressed, and more connected across its layers.

What appears as feeding from above is part of a larger structure moving through the water. The birds do not create it, and they do not remain once it passes. They mark it, briefly, making visible what is otherwise difficult to see.

Bird movement along the shoreline often draws attention toward activity that remains unseen beneath the surface. | Image credit: A. Mitchell

References

Castro, J. I. (1993). The shark nursery of bulls Bay, South Carolina, with a review of the shark nurseries of the southeastern coast of the United States. Environmental Biology of Fishes, 38(1-3), 37-48. https://doi.org/10.1007/bf00842902

Colwell, M. A. (2010). Shorebird ecology, conservation, and management. University of California Press.

Estes, J. A., Terborgh, J., Brashares, J. S., Power, M. E., Berger, J., Bond, W. J., Carpenter, S. R., Essington, T. E., Holt, R. D., C. Jackson, J. B., Marquis, R. J., Oksanen, L., Oksanen, T., Paine, R. T., Pikitch, E. K., Ripple, W. J., Sandin, S. A., Scheffer, M., Schoener, T. W., & Wardle, D. A. (2011). Trophic downgrading of planet Earth. Science, 33(6040), 301-306. https://doi.org/10.1126/science.1205106

Heithaus, M. R., Frid, A., Wirsing, A. J., & Worm, B. (2008). Predicting ecological consequences of marine top predator declines. Trends in Ecology & Evolution, 23(4), 202-210. https://doi.org/10.1016/j.tree.2008.01.003

Heupel, M. R., & Hueter, R. E. (2002). Importance of prey density in relation to the movement patterns of juvenile blacktip sharks ( Carcharhinus limbatus ) within a coastal nursery area. Marine and Freshwater Research, 53(2), 543-550. https://doi.org/10.1071/mf01132

Peterson, C. H., & Peterson, N. M. (1979). Ecology of intertidal flats of North Carolina: A community profile (79/39). FWS/OBS. https://pubs.usgs.gov/publication/fwsobs79_39

Piersma, T. (1997). Do global patterns of habitat use and migration strategies Co-evolve with relative investments in Immunocompetence due to spatial variation in parasite pressure? Oikos, 80(3), 623-631. https://doi.org/10.2307/3546640

Poole, A. F., Bierregaard, R. O., & Martell, M. S. (2002). Osprey (Pandion haliaetus). In The Birds of North America (1st ed.). Cornell Lab of Ornithology.

Safina, C., & Burger, J. (1985). Common tern foraging: Seasonal trends in prey fish densities and competition with bluefish. Ecology, 66(5), 1457-1463. https://doi.org/10.2307/1938008

Shields, M. (2014). Brown Pelican (Pelecanus occidentalis). In Birds of North America (1st ed.). Cornell Lab of Ornithology.

Wright, L., Short, A., & Green, M. (1985). Short-term changes in the morphodynamic states of beaches and surf zones: An empirical predictive model. Marine Geology, 62(3-4), 339-364. https://doi.org/10.1016/0025-3227(85)90123-9

May 9, 2026
Where the Water Moves Before the Storm: Sharks, Estuaries, and the Illusion of Shelter in Onslow County

Where the Water Turns Before the Storm

There’s a version of this story that shows up often—sometimes in films, sometimes in passing explanations—that when a large storm approaches, sharks move into estuaries to escape the violence of the open ocean.

It makes intuitive sense.

The ocean becomes something unmanageable—waves building, wind stacking energy across the surface. And just inland, the estuary appears contained. Narrower. Protected. A place where the water feels like it should be quieter.

But if you stand at the edge of a tidal creek before a storm, what you see first isn’t protection.

It’s change.

The surface tightens. Wind presses across it—not yet breaking it into waves, but organizing it into long, directional movement. The irregular texture of a normal day disappears into something aligned. Purposeful.

Water levels begin to rise before rainfall arrives. The boundary between water and marsh softens. Spartina no longer holds a sharp edge. The ground beneath your feet gives way more easily, saturated beyond its usual resistance.

Water moving through a beach access during storm conditions along the North Carolina coast, as rising levels and wind-driven flow begin to overtake the boundary between ocean and land. | Image credit: J. Armstrong

This is the first shift.

Not force, but redistribution.

And everything in the system is already responding.

What Lives Here When the System Starts Moving

The sharks that use estuaries are not here because these places offer protection from storms.

They are here because of what you can’t always see at first glance.

A juvenile blacktip shark (Carcharhinus limbatus) doesn’t move through open water the way people imagine sharks do. It stays in the shallows—along the edges where the water darkens slightly, where small schools of fish break apart and reform, where the bottom shifts from sand to scattered shell. These areas are harder for larger predators to move through quickly. Not impossible—but slower, more complicated.

Blacktip sharks move through estuaries in Onslow County, North Carolina, using shallow water where depth, structure and movement shape where they travel. | Image credit: kseym001, iNaturalist

That difference matters when you’re small.

What scientists describe as “structure” is this: broken bottom, uneven depth, patches of grass, oyster shell, shadow, current seams. From the shoreline, it just looks like variation. To a young shark, it’s the difference between being exposed and being able to disappear for a second.

That’s why these areas are used as nurseries—not because they are safe, but because they are less predictable in a way that favors smaller animals (Heupel et al., 2007).

From a distance, it looks like open water. Up close, it’s a series of edges—grass, mud, and channels—where movement slows, shifts, and concentrates. | Image credit: A. Mitchell

An Atlantic sharpnose shark (Rhizoprionodon terraenovae) uses that same space differently. You wouldn’t see it cruising the center of a channel. You’d find it where things intersect—along the drop where shallow water slips into deeper flow, near the edges of grass beds, or where current carries small prey out of the marsh and into open water.

It’s not avoiding predators in the same way a juvenile blacktip is.

It’s positioning itself where food moves, while still staying just out of the most exposed water (Ulrich et al., 2007).

Even the bonnethead shark (Sphyrna tiburo)—often described as a “benthic feeder”—is easier to understand if you ignore the word and watch the behavior. It spends time over the bottom, moving slowly across seagrass beds and sandy patches, nosing through the substrate for crabs and small invertebrates.

You’re most likely to notice it not by seeing the whole animal, but by the movement it leaves behind.

A subtle disturbance. A shift in the grass. A shape that doesn’t hold still long enough to resolve.

It’s also one of the few sharks you’re likely to find deeper into the estuary, where the water begins to lose its salt edge. Bonnetheads can tolerate lower salinity than many coastal sharks, which allows them to follow food farther into these mixed waters rather than staying closer to the inlet (Bethea et al., 2007).

Not because it’s calmer there.

Because the feeding opportunities extend into that space.

These sharks are here because the estuary offers layers—places to feed, places to pass through, places where movement is broken up just enough to matter (Knip et al., 2010; Bangley et al., 2018).

But all of those layers depend on something staying consistent—edges holding their shape, water moving in predictable directions, and clarity allowing animals to track one another.

And those are the first things a storm begins to take apart.

The Problem With “Shelter”

When a hurricane approaches, an estuary does not become a refuge.

It becomes harder to read.

If you stand on the ocean side of Topsail Island, you’ll see the change first as energy—waves building, spacing tightening, the surface lifting and falling with more force than it did the day before. But if you cross to the other side of the island—along the Intracoastal Waterway or into Stump Sound—it doesn’t look like that.

There, it rises.

Steadily. Quietly. Without the same visible force.

And that difference is exactly why the idea of “shelter” feels convincing.

On the ocean side, the storm is easier to recognize. Energy builds into waves, making the movement visible in a way it isn’t on the other side of the island. | Image credit: WITN-TV. On the sound side, it doesn’t look like a storm in the same way. The water rises and shifts along the shoreline, even as the system is already building offshore. | Image credit: A. Mitchell

Under normal conditions, these waters are connected—but they don’t move together. Ocean tides enter through New River Inlet and New Topsail Inlet, then work their way through the back-barrier system—the marshes, the Intracoastal, the sounds. That movement slows as it spreads out, which is why tides behind the island can lag the ocean by hours (Friedrichs & Aubrey, 1988).

From the shoreline, it feels like separation.

Like the ocean is doing one thing, and the water behind the island is doing another.

As a storm approaches, that timing begins to compress. Wind pushes water through the inlets faster than the system can distribute it, while water already inside has less opportunity to drain back out.

What was once staggered in time begins to overlap.

Storm surge doesn’t just raise water levels—it disrupts the normal exchange between ocean and estuary, forcing water inland and holding it there longer than a typical tidal cycle (National Oceanic and Atmospheric Administration, 2023).

That’s why the sound side doesn’t look violent at first.

It’s not because it’s protected.

It’s because it’s filling.

You can watch it happen without measuring anything. The usual drop after high tide doesn’t come when you expect it. Water continues to rise or holds in place. The difference between ocean and sound begins to disappear—not because the ocean calms down, but because the back-barrier system begins to behave more like a single body of water under pressure.

Edges blur as marsh grass floods from below. The bottom disappears as suspended sediment increases, and runoff and resuspension mix material into the water column faster than it can settle (Mallin et al., 1999).

The system is no longer cycling. It’s shifting faster than it can recover, with the patterns that usually hold it together breaking down in real time (Resh et al., 1988).

It’s accumulating.

And once that happens, the things that made this environment usable begin to disappear with it.

Where the Larger Sharks Actually Go

If an estuary loses the very structure that makes it usable during a storm, then the question shifts.

Sharks are not staying in place and enduring that change.

They are moving with it.

But not in the way we tend to imagine.

They don’t need to move into something more protected, because the ocean itself isn’t uniform. What looks chaotic at the surface is layered, and that layering holds even as a storm passes overhead. Wave energy dissipates quickly with depth, which means that the violence you see from the beach does not extend indefinitely downward.

A few meters below the surface, movement changes.

Deeper still, it stabilizes.

From above, the structure becomes visible—shallow bars, deeper channels, and the connections between ocean and estuary that shape how water moves through the system. | Image credit: Town of Topsail Beach

For larger coastal sharks like the bull shark (Carcharhinus leucas), that difference matters more than distance from shore. They are not choosing between rough ocean and calm estuary.

They are moving within a three-dimensional space.

And they sense the change before it arrives. It’s the same shift you feel before a storm—the air getting heavier, the pressure dropping, something changing before you can point to it. In the water, that change travels differently, and sharks begin responding to it well before anything looks different at the surface (Papastamatiou et al., 2015).

From the shoreline, it can feel like the storm suddenly arrives. But for animals in the water, it doesn’t. The change builds, and they are already moving within it—shifting position, adjusting depth, following the parts of the system that are still holding together as everything else begins to change long before it’s visible from the shoreline (Heupel et al., 2003).

Where the Shallow-Water Sharks Go

The sharks that spend their time in these shallow systems don’t have the same options as those offshore, because there is no deeper layer to move into when conditions begin to change. Instead, their response is tied to what parts of the system still hold together. As water levels rise and flow patterns begin to shift, the backs of creeks and the shallowest flats are often the first places to lose definition. These are areas where water can become cut off or overly mixed, where direction is no longer consistent, and where the features that usually structure movement begin to disappear.

What follows is not a movement further inland, but a gradual pulling back toward places that remain more stable. That often means deeper channels, intersections where water is still moving in a defined direction, or areas closer to inlets where exchange is still occurring. Rather than leaving the estuary entirely, many individuals consolidate within the portions of it that continue to function in a recognizable way. This kind of movement—shifting position as conditions change rather than holding in place—has been observed in coastal sharks as these systems begin to break down (Heupel et al., 2003).

At the same time, the system itself is expanding beyond its usual boundaries. Storm surge and flooding connect environments that are typically separate, allowing water to move across marsh, into low-lying land, and through built spaces like roads, canals, and retention areas. When that happens, animals already present in the water column move with it, not because they are selecting those environments, but because the physical structure that normally contains them is temporarily absent. Observations of sharks and other marine species in flooded coastal areas are most often associated with these short-lived hydrological connections rather than deliberate movement into unfamiliar habitats (Snelson et al., 1984).

As water spreads across the landscape, the system expands with it—connecting marsh, channels, and developed areas into a single, continuous space. | Image credit: C. Mitchell, AccuWeather

As water recedes, those connections close just as quickly as they formed. The system contracts, and the pathways that briefly allowed movement into those spaces disappear. Animals either move back with the retreating water or are left in conditions that no longer support them. What appears from the outside as unusual behavior is, in most cases, the result of a system that has temporarily lost its boundaries and then reestablished them.

Where the Assumption Breaks

The idea that sharks move into estuaries for shelter during storms rests on a simple assumption: that calmer-looking water offers protection. From the shoreline, that assumption is easy to make. The ocean side of Topsail Island shows the storm first—waves building, energy increasing—while the waters behind the island, along the Intracoastal Waterway and within Stump Sound, often appear quieter in the early stages. But that difference is not a separation of systems. It is a difference in timing.

Under normal conditions, tidal exchange through New River Inlet and New Topsail Inlet distributes ocean energy into the back-barrier environment with a delay, shaped by channel geometry and friction. That lag creates the appearance that one side of the island is responding differently than the other, when in reality both are part of the same connected system (Friedrichs & Aubrey, 1988). As storm conditions intensify, that delay compresses. Water is pushed through the inlets more rapidly than the system can accommodate, and the distinction between ocean and estuary begins to collapse into a single, continuous response driven by surge, wind, and pressure (NOAA, 2023).

Sharks are responding to that shift the entire time, not by seeking out calm water, but by staying within parts of the system that hold their structure for as long as they can. Offshore, that structure exists vertically, allowing movement into deeper, more stable layers. Within estuaries, it exists horizontally and can disappear quickly as gradients break down. The concept of “shelter” depends on the persistence of those gradients—clear edges, directional flow, and predictable relationships between different parts of the system—but during a storm, those features are among the first to be altered.

What remains after the storm is not evidence of animals moving into safer spaces, but the memory of contrast between what those spaces usually are and what they became under changing conditions. That contrast is compelling enough to shape interpretation, even when the underlying processes point to a different explanation.

After the water recedes, the boundary remains shifted—marking where movement passed through, rather than where it began. | Image credit: J. Lester

References

Bangley, C. W., Paramore, L., Shiffman, D. S., & Rulifson, R. A. (2018). Increased abundance and nursery habitat use of the bull shark (Carcharhinus leucas) in response to a changing environment in a warm-temperate Estuary. Scientific Reports, 8(1). https://doi.org/10.1038/s41598-018-24510-z

Bethea, D., Buckel, J., & Carlson, J. (2004). Foraging ecology of the early life stages of four sympatric shark species. Marine Ecology Progress Series, 268, 245-264. https://doi.org/10.3354/meps268245

Ebert, D. A., Dando, M., & Fowler, S. (2021). Sharks of the world: A complete guide. Princeton University Press.

Friedrichs, C. T., & Aubrey, D. G. (1988). Non-linear tidal distortion in shallow well-mixed estuaries: A synthesis. Estuarine, Coastal and Shelf Science, 27(5), 521-545. https://doi.org/10.1016/0272-7714(88)90082-0

Heupel, M., Carlson, J., & Simpfendorfer, C. (2007). Shark nursery areas: Concepts, definition, characterization and assumptions. Marine Ecology Progress Series, 337, 287-297. https://doi.org/10.3354/meps337287

Heupel, M. R., Simpfendorfer, C. A., & Hueter, R. E. (2003). Running before the storm: Blacktip sharks respond to falling barometric pressure associated with tropical storm Gabrielle. Journal of Fish Biology, 63(5), 1357-1363. https://doi.org/10.1046/j.1095-8649.2003.00250.x

Knip, D., Heupel, M., & Simpfendorfer, C. (2010). Sharks in nearshore environments: Models, importance, and consequences. Marine Ecology Progress Series, 402, 1-11. https://doi.org/10.3354/meps08498

Mallin, M. A., Posey, M. H., Shank, G. C., McIver, M. R., Ensign, S. H., & Alphin, T. D. (1999). Hurricane effects on water quality and benthos in the cape fear watershed: Natural and anthropogenic impacts. Ecological Applications, 9(1), 350. https://doi.org/10.2307/2641190

NOAA. (2024, June 16). What is storm surge? National Ocean Service website. https://oceanservice.noaa.gov/facts/stormsurge-stormtide.html

Papastamatiou, Y. P., Watanabe, Y. Y., Bradley, D., Dee, L. E., Weng, K., Lowe, C. G., & Caselle, J. E. (2015). Drivers of daily routines in an ectothermic marine predator: Hunt warm, rest warmer? PLOS ONE, 10(6), e0127807. https://doi.org/10.1371/journal.pone.0127807

Pine, W. E., Pollock, K. H., Hightower, J. E., Kwak, T. J., & Rice, J. A. (2003). A review of tagging methods for estimating fish population size and components of mortality. Fisheries, 28(10), 10-23. https://doi.org/10.1577/1548-8446(2003)28[10:arotmf]2.0.co;2

Resh, V. H., Brown, A. V., Covich, A. P., Gurtz, M. E., Li, H. W., Minshall, G. W., Reice, S. R., Sheldon, A. L., Wallace, J. B., & Wissmar, R. C. (1988). The Role of Disturbance in Stream Ecology. Journal of the North American Benthological Society; Freshwater Science, 7(4). https://doi.org/10.2307/1467300

Ulrich, G. F., Jones, C. M., Driggers III, W. B., Drymon, J. M., Oakley, D., & Riley, C. (2007). Habitat Utilization, Relative Abundance, and Seasonality of Sharks in the Estuarine and Nearshore Waters of South Carolina. American Fisheries Society Symposium, 50, 125-139. https://lowcountryinstitute.org/images/research/dox/Ulrichetal2007.pdf

Valiela, I., & Cole, M. L. (2002). Comparative evidence that salt marshes and mangroves may protect seagrass meadows from land-derived nitrogen loads. Ecosystems, 5(1), 92-102. https://doi.org/10.1007/s10021-001-0058-4

April 17, 2026
When the Bottom Moves: Rays in the Shallows of Onslow County

What People Are Seeing

In the last few weeks, the water along the edges of Onslow County has felt different.

Not because the water itself has changed—but because something beneath it has become harder to ignore.

Schools of cownose ray (Rhinoptera bonasus) move just below the surface nearshore, their wingbeats lifting faint clouds from the bottom as they pass. In the soundside shallows, where the water thins over sand and mud, Atlantic stingray (Hypanus sabinus) settle into the substrate, half-buried and nearly invisible until a step comes too close and the outline breaks.

People are seeing them more often now—but they’re also reacting to them.

A pause mid-step in shallow water.
A quick shift backward when something moves.
Fishermen lifting a line and stopping for a second longer than usual—not what they expected to find.

There is awe in it.

And sometimes hesitation.

Because the same thing that makes them easy to notice now also makes them easy to miss.

The question follows quickly:

Are there more of them this year?

Maybe.

But that question lingers longer than the answer.

Cownose rays migrating in Swansboro, NC. | Image credit: Pogie’s Academy

What Brings Them Here

As spring settles in along the North Carolina coast, the system begins to reorganize.

Water temperatures rise, and with that rise comes a shift in metabolism. Rays—like many coastal species—become more active as conditions move into a narrower range that supports feeding and movement (Smith & Merriner, 1987; Schwartz & Dahlberg, 1978).

For cownose rays, this seasonal transition includes a northward migration along the Atlantic coast, bringing large groups into nearshore and estuarine waters (Smith & Merriner, 1987).

Large groups of cownose rays like these move north along our coast each season, arriving together in shallow water. | Image credit: Vidyacharan A. Alchi

But movement alone does not explain what people are seeing.

What matters is where that movement meets the structure of the environment.

The water does not always look the same—some days it is flat and clear enough to see straight to the bottom, and other days the slightest movement turns it cloudy, changing what can be seen and what remains hidden (Peterson et al., 2001).

And beneath all of it is food.

Cownose rays move through the shallows, sweeping across the bottom and disrupting what lies beneath them, crushing clams, oysters, and other shelled invertebrates with broad, flattened tooth plates (Collins et al., 2007; Fisher, 2010).

Atlantic stingrays hold low against the bottom, burying into the sand as they feed and working within the sediment itself—not moving across it—uncovering and drawing in small invertebrates hidden below (Snelson et al., 1988; Schwartz & Dahlberg, 1978).

Atlantic stingrays hold close to the bottom, often blending in until something shifts and gives them away. | Image credit: Andy Murch

Where prey is accessible, rays follow.

Where prey is concentrated in shallow, warming water, rays do not just pass through—they stay, turn, feed, and linger.

And in doing so, they cross into the same narrow band of space where people enter the water (Bangley et al., 2018).

They are not simply “here more.”

They are here in ways—and in places—that make them visible.

What Happens When They Feed

When a ray feeds, the bottom does not remain the same.

A cownose ray moving across a flat is not just searching—it is actively restructuring the surface beneath it. As it passes, the bottom is turned over behind it, patches of sand and mud disturbed where clams and other buried life have just been uncovered and crushed (Peterson et al., 2001; Smith & Merriner, 1985).

Feeding pits left behind by rays. Easy to mistake for crab holes at first—until you start to recognize the pattern and what’s actually shaping the bottom. | Image credit: Giaroli et al., 2024

Atlantic stingrays leave a different kind of trace. Where they settle, the surface shifts more subtly—small depressions, softened patches, places where the sediment has been worked rather than overturned, as buried invertebrates are uncovered and drawn in (Snelson et al., 1988; Schwartz & Dahlberg, 1978).

This is bioturbation—the bottom being reworked by the animals moving through it and within it (Thrush & Dayton, 2002).

As they feed, the bottom lifts into the water—fine particles rising and hanging there, turning clear water slightly cloudy (Thrush & Dayton, 2002).

The water does not stay still—the bottom here is constantly shifting, the way much of this coastline does, even when it appears unchanged.

And neither does the system.

Oysters and clams quietly filter the water as they feed, and when their numbers shift—even in small areas—the water and everything moving through it begins to change with them (Newell, 2004; zu Ermgassen et al., 2013).

In places where rays have been feeding, those filtering communities can be reduced or redistributed (Peterson et al., 2001).

Not removed entirely—but changed.

And that change does not stay in one place.

It moves outward, carried in the way the water looks, the way it settles, and what it can hold.

Layers of the Food Web

Rays do not sit at the top of the system, and they are not at the bottom of it.

As mesopredators, they feed on what is buried in the sediment, but they are also available to what moves through the water above. That position—between—links parts of the system that do not often meet directly (Myers et al., 2007; Heithaus et al., 2008).

What they do in that space matters.

As cownose rays move through andAtlantic stingrays work within the bottom, they are not just feeding—they are shaping what persists there. Clams, oysters, and other invertebrates do not simply accumulate unchecked. Their numbers are reduced, redistributed, and in some places kept from becoming dominant (Peterson et al., 2001).

Movement like this doesn’t stay in one place for long.

That pressure shapes the bottom itself.

Bivalves filter the water. Invertebrates stabilize sediment. When their abundance shifts, the system responds—sometimes toward clearer water, sometimes toward more suspended material, depending on what remains and where (Newell, 2004; zu Ermgassen et al., 2013).

Rays do not create those conditions alone—but they influence which direction the system moves.

At the same time, they carry that energy upward.

Juvenile sharks moving through these shallow waters encounter not just prey, but a system already in motion—areas where the bottom has been disturbed, where feeding has recently occurred, where something has been uncovered or displaced (Bangley et al., 2018).

And in some cases, the rays themselves become part of that exchange.

This is what it means to sit in the middle.

Not just connecting layers—but regulating how energy and movement pass between them.

If that middle shifts, the balance does not disappear.

It changes direction.

Why It Feels Sudden

There is a moment, standing in shallow water, when the bottom stops feeling like something you can trust.

What looked like sand shifts.
What felt still is no longer still.

Sometimes you notice it in time—a shape lifting away, a shadow moving just beneath the surface. A plume of fine sediment rising to the surface under a paddleboard with a trail following it.

The moment when the bottom stops looking empty. | Image credit: iStock

Sometimes you don’t.

A step comes down where something is already settled.
Hidden in the sand.
Working within it.

The reaction is immediate.
Surprise first. Then pain. Then the realization of what was there all along.

It is easy, in that moment, to think something unexpected has happened—the same kind of sudden awareness that comes when something just beneath the surface reveals itself.

But what you are stepping into is not a single event.

It is a convergence.

Water temperatures have risen, bringing rays into the shallows as they feed and move through these systems (Smith & Merriner, 1987; Schwartz & Dahlberg, 1978).

Tides narrow the space, concentrating movement into a thinner band of water.

The bottom has already been worked—turned by cownose rays moving through, disturbed by Atlantic stingrays holding within it.

And at the same time, people have returned to the water.

For a brief window, all of it overlaps.

Not more.
But more visible.

It feels sudden because you are standing at the point where all of these things meet.

And for a moment, the system lets you see it.

References

Bangley, C. W., Paramore, L., Dedman, S., & Rulifson, R. A. (2018). Delineation and mapping of coastal shark habitat within a shallow lagoonal Estuary. PLOS ONE, 13(4), e0195221. https://doi.org/10.1371/journal.pone.0195221

Giaroli, M. L., Byrne, I., Gilby, B. L., Taylor, M., Chargulaf, C. A., & Tibbetts, I. R. (2024). The distribution and significance of stingray feeding pits in Quandamooka (Moreton Bay), Australia. Marine and Freshwater Research, 75(18). https://doi.org/10.1071/mf23247

Heithaus, M. R., Frid, A., Wirsing, A. J., & Worm, B. (2008). Predicting ecological consequences of marine top predator declines. Trends in Ecology & Evolution, 23(4), 202-210. https://doi.org/10.1016/j.tree.2008.01.003

Kolmann, M. A., Huber, D. R., Motta, P. J., & Grubbs, R. D. (2015). Feeding biomechanics of the cownose ray, Rhinoptera bonasus, over ontogeny. Journal of Anatomy, 227(3), 341-351. https://onlinelibrary.wiley.com/doi/full/10.1111/joa.12342

Myers, R. A., Baum, J. K., Shepherd, T. D., Powers, S. P., & Peterson, C. H. (2007). Cascading effects of the loss of APEX predatory sharks from a coastal ocean. Science, 315(5820), 1846-1850. https://doi.org/10.1126/science.1138657

Newell, R. I. (2004). Ecosystem influences of natural and cultivated populations of suspension-feeding bivalve molluscs: A review. 23(1), 51–61. Journal of Shellfish Research, 23(1), 51-61. https://go.gale.com/ps/i.do?id=GALE%7CA118543914

Peterson, C. H., Fodrie, J. F., Summerson, H. C., & Powers, S. P. (2001). Site-specific and density-dependent extinction of prey by schooling rays: generation of a population sink in top-quality habitat for bay scallops. Oecologia, 129, 349-356. https://link.springer.com/article/10.1007/s004420100742

Schwartz, F. J., & Dahlberg, M. D. (1978). Biology and ecology of the Atlantic Stingray, Dasyatis Sabina (Pisces: Dasyatidae) in North Carolina and Georgia. Northeast Gulf Science, 2(1). https://doi.org/10.18785/negs.0201.01

Smith, J. W., & Merriner, J. V. (1985). Food habits and feeding behavior of the Cownose ray, Rhinoptera bonasus, in lower Chesapeake Bay. Estuaries, 8(3), 305. https://doi.org/10.2307/1351491

Smith, J. W., & Merriner, J. V. (1987). Age and growth, movements and distribution of the Cownose ray, Rhinoptera bonasus, in Chesapeake Bay. Estuaries, 10(2), 153. https://doi.org/10.2307/1352180

Snelson, F. F., Williams-Hooper, S. E., & Schmid, T. H. (1988). Reproduction and ecology of the Atlantic Stingray, Dasyatis Sabina, in Florida coastal lagoons. Copeia, 1988(3), 729. https://doi.org/10.2307/1445395

Thrush, S. F., & Dayton, P. K. (2002). Disturbance to marine benthic habitats by trawling and dredging: Implications for marine biodiversity. Annual Review of Ecology and Systematics, 33(1), 449-473. https://doi.org/10.1146/annurev.ecolsys.33.010802.150515

Zu Ermgassen, P. S., Spalding, M. D., Blake, B., Coen, L. D., Dumbauld, B., Geiger, S., Grabowski, J. H., Grizzle, R., Luckenbach, M., McGraw, K., Rodney, W., Ruesink, J. L., Powers, S. P., & Brumbaugh, R. (2012). Historical ecology with real numbers: Past and present extent and biomass of an imperilled estuarine habitat. Proceedings of the Royal Society B: Biological Sciences, 279(1742), 3393-3400. https://doi.org/10.1098/rspb.2012.0313

April 11, 2026
Where the Coast Keeps Its Wrecks: Shipwrecks Along Onslow County, North Carolina

Encountering the Past in the Sand: When the Beach Opens

There are mornings when the beach feels newly made.

The tide has pulled back just enough to smooth the sand into a long, pale sheet, the wind from the night before erased except for faint ripples that catch the light at an angle. Ghost crab tracks cross and recross the surface, stitching together small territories that vanish with the next wave. The wrack line sits just above the reach of the water—shells, grasses, fragments of offshore life placed carefully along a boundary that shifts a little each day.

And then, walking that line, something interrupts the pattern.

At first it looks like driftwood. Dark. Angular. Out of place, but not unusual. But the closer you get, the more it resists that explanation. The pieces are too regular, too aligned. The sand around it feels different underfoot—firmer, compacted, as though something beneath it has been holding shape long before this tide receded.

What emerges is not debris, but structure.

Ribs of timber curve in a way that only makes sense once you recognize them as part of a hull. Iron fastenings stain deep into the grain. The geometry of a vessel that once moved across this water now rests within it.

The beach has not received this. It has revealed it.

What remains of the William H. Sumner when shifting sand briefly reveals it along the shoreline. | Photo credit: A. Mitchell

Along the Onslow County coast, shipwrecks do not arrive as singular events. They exist in cycles of concealment and return. Storms strip sand away. Longshore currents redistribute what was settled. A wreck that has been buried for decades can appear in a single tide cycle, as if placed there overnight, only to be covered again before the week ends.

The shoreline is not a surface. It is a moving archive (Riggs & Ames, 2003).

A Coast That Does Not Hold Still

Standing at the edge of the water, the coastline can appear steady, almost fixed, as though the boundary between land and ocean has settled into a reliable position. The horizon holds its line. Waves repeat their approach in familiar intervals. Even the inlets, from a distance, seem to occupy defined openings in the land.

But that stability is a surface impression.

Beneath it, the coastline is in constant adjustment. Sand moves even when the water appears calm, carried alongshore by currents that shift direction with changing wind and wave conditions. Bars form offshore, migrate, and dissolve. Channels deepen and fill. The openings at places like New River Inlet or Topsail are not permanent features so much as temporary alignments of water and sediment, reshaped seasonally and sometimes abruptly after storms.

For someone approaching from offshore, especially before modern navigation, this would not have presented as a clear pathway but as uncertainty. Depth changes could occur over short distances. A channel that allowed passage one season might be obstructed the next. What looked like open water could rise into a shoal just beneath the surface, invisible until it was encountered.

Ships moving along this coast were not simply traveling past it. They were moving across a landscape that was itself in motion.

When a vessel grounded here, it was often not because of a single error, but because the environment it relied on for passage had already changed. The ship met a bottom that no longer matched expectation, and once contact was made, wave energy did the rest—breaking the structure apart and distributing its remains across the same shifting system that had caused the grounding.

Over time, those remains became part of that movement. Buried, exposed, and buried again as sand continued to migrate, they settled into the coastline not as isolated events but as elements within an ongoing process.

What appears now as a sudden discovery—a line of timbers revealed after a storm—is not the arrival of something new, but a brief moment when the motion of the coast allows what has long been present to be seen again.

Vessels Carried Into This Coast

An early French map depicting the coastal regions of the Carolinas and Georgia before the American Revolution from an antique map, the “Carte de la Caroline et Georgie” by Jacques-Nicolas Bellin, published around 1773.

Walk this shoreline long enough and shipwrecks begin to feel less like isolated events and more like recurring encounters with the same conditions. Different vessels, different centuries, but the same meeting between movement and a coast that does not stay where it was. What changes is not only the vessel, but the way it is lost.

Two Ways a Ship Becomes Part of the Sea

Not all shipwrecks begin the same way. Some are lost far offshore, where depth replaces sand as the defining feature. A vessel may be damaged by storm, fire, or attack, take on water, and settle downward through open water until it reaches the seafloor. The descent is vertical, the structure often remaining largely intact as it comes to rest in deeper, more stable conditions. These wrecks lie beyond the horizon, where the bottom changes more slowly and the surrounding water does not rearrange them in the same way (Ward et al., 1999; Hoyt et al., 2021).

Others meet the coast itself. Along barrier shorelines like Onslow County, ships often do not sink all at once. They run aground. A hull meets sand where water had been expected, forward motion stops, and the energy of waves and tide begins to work against the structure. The vessel lifts, pivots, and settles unevenly as water moves beneath and around it. Over time, it breaks apart. What remains is not a single intact form, but a field of structure distributed across the seabed and shoreline (Riggs & Ames, 2003; Pilkey, 1998).

Both are shipwrecks, but they belong to different processes. One settles into depth. The other becomes part of a coast that does not hold still.

Pirate Waters

Model of the Queen Anne’s Revenge | Photo credit: Qualiesin, licensed under CC BY-SA 4.0.

Long before modern navigation, these waters were already understood as difficult to pass through cleanly. The channels around what is now Topsail Island were narrow, shifting, and often uncertain from offshore. What appears now as a continuous coastline is, and always has been, a series of openings that do not hold their shape for long.

Even today, that instability can be seen without leaving shore. After a strong storm or a week of changing wind, the edge of the waterline shifts, bars appear where there had been none, and shallow areas extend farther out than expected. A stretch of water that looked open a few days earlier begins to break differently, waves lifting and folding over something just beneath the surface. The bottom has moved, even if the horizon has not (Riggs & Ames, 2003; Pilkey, 1998).

For a vessel approaching from offshore, especially without precise depth measurements, that change would not be visible until it was too late. The hull would meet sand where water had been expected. Forward motion would slow abruptly, then stop, while the energy of the sea continued to act on the vessel. Waves begin to lift and drop the structure unevenly, pivoting it sideways, driving it further onto the bar. What had been a path forward becomes a fixed point under pressure (Riggs et al., 1995; Delgado, 1997).

Stories persist that pirates used this uncertainty to their advantage, positioning themselves within these shifting inlets where passing ships were forced into slower, more confined routes. Whether or not every account is precise, the setting itself made such encounters possible.Further north along this same coastline, in 1718, Blackbeard ran his flagship Queen Anne’s Revenge aground while entering what is now Beaufort Inlet. The ship struck a shallow shoal at the mouth of the inlet, where water depths even today remain modest—on the order of twenty to twenty-five feet at the wreck site. Rather than sinking intact into the deep ocean, it remained within a high-energy, shallow environment where waves and tidal currents gradually broke it apart. Its remains settled into the seabed and have since been buried and re-exposed as sediment continues to move across the inlet (Wilde-Ramsey & Carnes-McNaughton, 2016; Wilde-Ramsing & Carnes-McNaughton, 2018).

To learn more about Blackbeard’s Queen Anne’s Revenge Shipwreck, watch the Nautilus Productions video.

Colonial Trade and Storm-Driven Wrecks

By the mid-eighteenth century, heavily loaded merchant vessels were moving along this coastline as part of transatlantic trade. Their routes followed currents that offered efficiency, but those same currents carried them close to a shoreline that did not remain fixed.

In 1750, the Spanish ship El Salvador, part of a treasure fleet transporting gold and silver, encountered a hurricane that pushed it northward along the Gulf Stream. The storm did not introduce danger so much as concentrate it. Wind and current worked together, driving the vessel toward a coast already defined by shifting shoals and unstable inlets. Other ships in the same fleet were carried along the same path, driven ashore at different points along the Outer Banks, separated from one another by the same forces that moved them north (Shomette, 2008; Pilkey, 1998).

When El Salvador met the shoals, there was little margin left for recovery.

Only a small number of crew survived, carried ashore as the vessel came apart in the surf. The hull did not settle into the water as a whole. Instead, waves lifted and broke it against a bottom that would not hold it in one place. For a short time, portions of the structure remained visible—rigging, fragments of timber, the outline of something that had recently been intact. And then the shoreline resumed its movement. Sand shifted across what remained. Water moved through it. What had been a vessel became something distributed, its structure absorbed into sediment and carried within the same system that had stopped it, continuing to migrate along the coast (Riggs & Ames, 2003; Pilkey, 1998; Shomette, 2008).

The pattern holds: a vessel enters under force, meets a shifting bottom, and becomes part of it.

Steam and Certainty: Pulaski (1838)

The Pulaski is depicted during its boiler explosion | Image credit: C. Elms

By the early nineteenth century, steam navigation had begun to change expectations. Routes were more regular. Travel felt more predictable. Distance could be measured in time rather than uncertainty.

The coastline, however, had not changed.

When the steamship Pulaski exploded offshore of North Carolina in 1838, the rupture was immediate. What followed did not resolve as quickly. Survivors, separated into lifeboats and fragments of wreckage, were no longer traveling across water with direction. They were moving within it (North Carolina Department of Natural and Cultural Resources [DNCR], 2016).

They drifted for more than a day, in some cases closer to two.

There was no fixed path in that movement. Coordinates were not precisely recorded, and what direction remained was shaped by current, wind, and wave rather than intention. The horizon held its line, but offered no reference. The sun marked time without marking progress. Salt settled into the skin. Thirst extended the length of the day. Movement continued, but without a way to measure where it led.

Some survivors eventually reached the barrier islands along this stretch of North Carolina, carried by those same forces rather than guided toward land. Their arrival was not coordinated or immediate, but scattered—individual landings along a shoreline that did not announce itself as destination, only as the end of exposure (DNCR, 2016). Of its 150 passengers and 37 crew, only 59 survived (Falk, 2025).

The wreck remains offshore, beyond the shifting bars where waves no longer break it apart in the same way. It does not return to the surface in the way some grounded vessels do. It settles instead into deeper water, where structure changes more slowly and remains largely out of view.

The shoreline holds something else. Not the wreck itself, but the moment when motion without direction became arrival. A place where drifting resolved, not into discovery, but into contact—where water gave way to land, and movement, at last, found its edge.

Want to learn more about the Pulaski? Listen to a podcast from Shipwrecks and Seadogs about its history.

War Along the Inlets: New River

Blockade runner, Teaser, near Fort Monroe, Virginia, is an example of the blockade runners along our coastline. | Photo credit: MPI/Getty Images

During the Civil War, this coastline was not only a place of navigation, but of control.

New River Inlet, leading inland toward what is now Jacksonville, served as a potential access point between coastal waters and interior routes. Union naval forces patrolled the coast as part of a broader blockade, attempting to restrict movement of goods and supplies, while Confederate forces relied on smaller vessels and local knowledge of the waterways to move through the system (Browning, 2002; Stick, 1990).

For any vessel entering New River, the challenge would have been familiar.

The inlet itself was shallow and shifting, defined by sandbars that changed position with storms and tides. Navigation required timing, local knowledge, and an ability to read water that did not present itself clearly from offshore (Riggs & Ames, 2003).

Unlike some of the more widely known Civil War wreck sites along the North Carolina coast, there is no clear record of a major vessel sinking within New River itself. But the absence of a wreck does not mean the absence of difficulty. The conditions that prevent passage do not always leave a visible record. Any ship moving through that inlet would have encountered the same conditions that shape it today.

Shallow approaches, moving sand, and water that changes faster than it can be mapped. The difference is not in the coastline, only in the ships that attempt to pass through it.

Farther south along this same stretch of coast lies the Cape Fear Civil War Shipwreck District, a cluster of documented wreck sites near the approaches to the Cape Fear River and the port of Wilmington. These wrecks, concentrated off Brunswick, New Hanover, and parts of Pender County, represent vessels involved in the Confederate blockade-running trade. Ships attempting to slip past Union naval patrols carried cargo that ranged from military supplies and weapons to manufactured goods and cloth desperately needed in the South. Many were narrow, fast steamers built with shallow drafts and reinforced hulls designed to move quickly through inlets and across shoals. Their loss was not incidental, but patterned—occurring in a region where shifting channels, shallow bars, and the pressure of pursuit converged. Archaeological surveys of this coastline describe a dense concentration of wreck sites associated with these movements, forming one of the most significant Civil War maritime landscapes along the Atlantic seaboard (North Carolina Office of State Archaeology, n.d.; Browning, 2002; Hall, 2004).

Working Maritime Coast: William H. Sumner (1919)

The William H. Sumner circa 1919 and what remains today. | Photo credits: Cape Fear Museum of History and Science (left); A. Mitchell (right)

In 1919, the schooner William H. Sumner approached this same coastline carrying cargo northward. The conditions it encountered were not new. The channel it relied on had shifted beyond what the vessel could safely cross.

The grounding was not violent, but it was final.

Accounts from the time suggest that by the final days of the voyage, conditions aboard the vessel had already begun to shift. Rations had reportedly run low, and attention moved away from navigation. In the hours after the grounding, the captain was found dead in his cabin from a gunshot wound, and the ship’s mate was later charged with mutiny and murder. Testimony conflicted. Some described tension among the crew, others described familiarity and routine. The trial that followed ended without resolution, leaving the cause of the captain’s death uncertain (North Carolina Shipwrecks, n.d.; Wrightsville Beach Magazine, 2015).

Once the hull met the sandbar near Topsail Inlet, where multiple vessels have grounded over centuries of shifting channels, wave energy began to work against it, gradually breaking the structure apart (Riggs & Ames, 2003; Pilkey, 1998; Hall, 2004). Salvage efforts removed what could be taken. What remained did not leave with it. It settled into the shoreline system, where it was taken in and buried beneath moving sand (Riggs & Ames, 2003; Pilkey, 1998).

Over time, and then at intervals shaped by storms, it appeared again.

Storms and low tides continue to strip away the sand that covers portions of the wreck, exposing curved timbers that seem, for a short time, to return. These exposures are often described as discoveries, but the structure has been present throughout, shifting between visibility and concealment as sediment moves across it (Riggs & Ames, 2003). When these timbers reappear, they are not simply objects to be collected. As registered historic shipwreck remains, they are protected under state law, and removing or disturbing them is prohibited, preserving both the structure and the record it represents (ABC45 News, 2024).

The wreck does not travel. The coastline moves around it.

Wrecks Beyond the Shoals

Farther offshore, beyond the shifting bars and inlets, the nature of shipwrecks begins to change.

In deeper water, vessels are less likely to run aground and more likely to be lost through damage that begins within the ship itself—fire, structural failure, or, in the case of the North Carolina coast during World War II, torpedo strikes from German U-boats operating just off the continental shelf (Hoyt et al., 2021; Blair, 2000).

By the time of World War II, this stretch of coastline was already part of what is often called the “Graveyard of the Atlantic,” a name shaped by centuries of shipwrecks driven by storms, shifting shoals, strong currents, and difficult navigation along the North Carolina coast (Stick, 1990; Hoyt et al., 2021). The war did not create this pattern, but added to it, concentrating losses offshore as vessels were targeted in transit. Tankers and cargo ships moving along the eastern seaboard were struck at sea, often at night, their hulls breached below the waterline as they traveled.

The process is different. Instead of grounding, there is descent.

A vessel lists, loses buoyancy, and slips beneath the surface, settling onto the seafloor often in a more intact form than those broken apart in shallow surf. Once compromised, these ships took on water rapidly and sank into deeper channels where the seabed lay far below the reach of waves (Wells & McNinch, 1991).

In some cases, even when a wreck is located, its identity remains uncertain. Historical comparisons of structure, propulsion, and location have led to tentative identifications—such as the possible association of certain offshore remains with Civil War–era blockade runners—but these connections are not always definitive and may remain unresolved despite decades of study (Stallman, 2011).

Off the coast of Onslow County, these deeper wrecks remain present, though rarely visible from shore.These wrecks are not isolated features, but part of a broader offshore field of structure, scattered across the continental shelf. Some have been mapped and studied, while others remain only partially defined, their forms intact below the reach of waves. What defines them is not their visibility, but their persistence—structures that remain in place long after the events that created them, shaping the surrounding environment in ways that are not immediately seen.

Storm Without Shore: Normannia (1924)

The Normannia | Photo credit: Library of Congress

Vessels in deeper water faced a different kind of exposure than those nearer to the shoals.

In 1924, the Normannia foundered during a storm offshore. The forces at work were not those of shifting shoals, but of sustained wind, wave height, and structural stress. Far from the influence of the coastline’s sandbars, the vessel did not run aground. It remained in open water until the structure failed (Gentile, 1992).

As the hull lost integrity, water entered faster than it could be expelled. Stability gave way. The vessel listed, settled, and slipped beneath the surface (Gentile, 1992).

There was no bar to hold it, no shoreline to break it apart—only depth to receive it.

March 1942: A Concentrated Loss Offshore

In March of 1942, multiple vessels moving along this coastline were struck within a matter of days, part of a concentrated period of U-boat activity along the North Carolina coast.

Other vessels from this same period reflect the intensity of offshore loss during the war. The tanker Naeco, more than 400 feet in length, was struck by a torpedo from U-124 and broke apart before sinking, its bow and stern sections settling separately on the seafloor miles apart. The tanker Esso Nashville was also torpedoed that year; its bow section sank offshore while the stern remained afloat long enough to be recovered, later refitted and returned to service. When the tanker John D. Gill was struck by U-158, where 23 were lost and 26 survived, burning oil ignited on the water, creating a fire visible from shore, extending the event into the night sky itself (Taylor, 2025).

The John D. Gill (left) and the Naeco (left) | Photo credits: G. Gentile (left) and Marines Museum {right}

These vessels did not meet the coast through sand. They were lost to force applied below the waterline, their structures descending into deeper channels beyond the reach of waves (Hoyt et al., 2021; Blair, 2000; Wells & McNinch, 1991).

Over time, these wrecks become stable structures in deeper water, less influenced by shifting sand and more by currents, corrosion, and biological growth. They are still part of the same coastal system, but they are shaped by depth rather than motion (Paxton et al., 2023).

Likely a picture of the Esso Nashville, due to its stern configuration (left) and the starboard and bow anchor of the Esso Nashville (right) | Photo credits: G. Gentile (left) and P. Hudy (right)

War Along the Shore: Observation Without Contact

While vessels were being lost offshore, the coastline itself became part of the wartime landscape.

Along Topsail Island, a series of observation towers were constructed as part of Operation Bumblebee, where military personnel tracked missile tests and coastal activity from elevated positions above the shoreline. From these towers, the ocean was not empty space but an active field—ships moving along the horizon, and at times, evidence of conflict unfolding beyond direct reach (Island Life NC, 2025).

The coastline did not receive these wrecks.

But it witnessed them.

Collision in Transit: Cassimir (1942)

Not all vessels lost during this period were the result of attack.

The Cassimir, built in 1920, sank in 1942 following a collision with the freighter Lara. The loss occurred offshore, in deeper water, where the structure did not ground but instead descended to the seafloor. Its presence reflects a different kind of vulnerability—navigation intersecting with proximity rather than conflict or storm (Gentile, 1992).

The outcome, however, remains consistent.

The vessel did not meet sand.

It entered depth.

The Cassimer circa 1920 (left) and its anchor at the wreck site (right) | Photo credits: G. Gentile (left) and P. Hudy (right)

Modern Abandoned Vessels: Those That Become Something Else

Along the coast today, abandoned vessels follow a similar trajectory, though their timeline is still unfolding. Shrimp boats grounded on shoals or left after mechanical failure may remain in place for years, shifting slightly with storms but never fully leaving.

Abandoned shrimp vessel in Stump Sound | Photo credit: L. Caldwell

During that time, they begin to change.

Osprey use the elevated structure for nesting. Barnacles attach to submerged surfaces. Fish gather beneath the hull where shade and form offer protection. In a sandy coastal system, any stable structure creates opportunities for life to organize around it.

But what develops on these vessels depends strongly on where they come to rest.

When a boat grounds on a shoal or nearshore bar, the surrounding environment remains in constant motion. Waves pass through the structure with each tide cycle, sand migrates around the hull, and storms periodically bury or expose different portions of the wreck. Habitat in these places is shaped by disturbance. The organisms that establish themselves must tolerate shifting sediment, abrasion, and periodic exposure to air.

The first arrivals appear quickly. Within weeks, thin microbial films and algae coat the surfaces of exposed wood, steel, or fiberglass. Barnacles and oysters follow, attaching themselves wherever water continues to move across the hull. Mussels cluster along beams and ribs where currents deliver suspended food. Small fish begin to gather in the shadows beneath the structure—pinfish, blennies, and juvenile black sea bass slipping into crevices created by broken ribs or propeller shafts. Sheepshead move in to feed on barnacles and shellfish, while blue crabs and shrimp occupy pockets where sand collects between fragments.

Over time, the wreck becomes less a single object than a patch of structure embedded in the moving beach system. Sandbars migrate across it. Portions disappear beneath sediment, only to reappear after storms. Habitat here is temporary and episodic, shaped by the same forces that buried the vessel in the first place.

View interactive Map of Derelict Vessels in North Carolina.

Farther offshore, the process unfolds differently.

When a vessel sinks into deeper water beyond the reach of breaking waves, the surrounding seabed is more stable and the structure often settles largely intact. Steel hulls, decks, and internal compartments create vertical relief in a landscape otherwise dominated by sand. Hard surfaces are scarce along this portion of the continental shelf, and life responds quickly when they appear.

Shipwrecks in North Carolina reflect rich maritime history and are home to a diversity of marine life. | Photo credit: T. Casserley, NOAA.

Within weeks, bacterial films coat the structure. Barnacles, hydroids, and tube worms attach soon after, followed by sponges, anemones, and soft corals that require firm substrate to establish. Over months and years, these organisms layer over one another, transforming the wreck from bare metal or timber into something resembling natural reef.

Within weeks, bacterial films coat the structure. Barnacles, hydroids, and tube worms attach soon after, followed by sponges, anemones, and soft corals that require firm substrate to establish. Over months and years, these organisms layer over one another, transforming the wreck from bare metal or timber into something resembling natural reef.

Fish respond just as quickly. Small schooling species—tomtate, baitfish, and spadefish—begin to circle the structure, drawn to shelter and feeding opportunities. As prey accumulates, larger predators follow. Snapper and grouper hold close to the hull, amberjack patrol the upper water column, and barracuda and sharks move through the surrounding water where prey becomes concentrated (Bohnsack & Sutherland, 1985; Paxton et al., 2023).

In waters off North Carolina, these offshore wrecks are also known for attracting one of the coast’s most recognizable predators. Sand tiger sharks often patrol the edges of wreck sites along the continental shelf, moving slowly through the water column where schools of fish gather around the structure (Castro, 2011; Paxton et al., 2023). Unlike fast-moving pelagic sharks, sand tigers tend to hover deliberately near reefs and wrecks, conserving energy while watching the dense concentrations of prey that form there (Castro, 2011). Divers frequently encounter them circling shipwrecks in loose groups, their presence marking the final stage of a habitat that began as bare metal or timber settling onto an otherwise sandy seafloor (Paxton et al., 2023).

Over decades, these deeper wrecks can support complex communities that persist long after the vessel itself begins to corrode. The structure weakens slowly, but before it collapses it may host a dense network of organisms comparable to natural hard-bottom reefs.

A sand tiger shark patrols the SS Tarpon shipwreck. Scientists believe these sharks use shipwrecks as “rest stops” on their long migratory path from New England to Florida and can be beneficial for their conservation. | Photo credit: NOAA

Artificial Reefs and Intentional Sinking

Recognizing this ecological potential, many coastal states—including North Carolina—have intentionally sunk vessels as part of artificial reef programs. Before sinking, ships are stripped of fuels, wiring, plastics, and other materials that could pollute surrounding waters. What remains is the structural framework: steel decks, beams, and bulkheads that provide vertical complexity.

Once placed on the seafloor, these vessels follow much the same ecological trajectory as accidental wrecks, often more quickly because the structure is intact and positioned on a stable bottom. Fish communities can begin forming within months, with predators arriving as prey species establish themselves (Bohnsack & Sutherland, 1985; Pickering & Whitmarsh, 1997).

The resulting reef does more than host new organisms. It changes the surrounding environment. Currents interacting with the hull create eddies that trap plankton and organic material. Sand that once held little structure becomes a landmark on the seafloor where life gathers.

But the distinction between prepared artificial reefs and abandoned vessels remains important. Ships intentionally sunk for reef programs are cleaned to reduce contamination, while vessels left to deteriorate in place undergo corrosion and material breakdown that can introduce contaminants into surrounding waters as their structure degrades (MacLeod, 2006).

Even so, the ecological impulse is the same. Wherever the coast receives structure, life organizes around it.

In some cases, this ecological response has led coastal managers to intentionally place vessels on the seafloor as artificial reefs, recognizing that stable structure can support complex marine communities. Along this coastline, however, similar structures are not treated in the same way. Some wrecks are preserved as part of the historical record, protected because they represent events that cannot be reconstructed once disturbed. Others are managed as hazards, their removal shaped by environmental risk and navigational safety. Still others are placed deliberately, prepared and sunk to provide habitat without the long-term effects of deterioration. What appears similar from the surface carries different meanings depending on how it is understood—as a record, a risk, or a design.

Along the Topsail Island coast, vessels have been intentionally placed on the seafloor as part of North Carolina’s artificial reef program, where cleaned ships are sunk to create habitat for fish and other marine life while providing new structure in otherwise sandy environments (Report, 2024).

What the Coast Does With What We Leave Behind

Shipwrecks are often described as endings, but along the Onslow coast they function more as transitions.

A vessel moves through stages. It carries people and cargo, meets a coastline that does not hold still, and becomes structure. That structure gathers life, shifts within the movement of sand, and settles into memory. The boundaries between these stages are not fixed. They move with the same currents and tides that shape the shoreline itself.

Nothing here is entirely lost. It is redistributed.

Wood, iron, fiberglass, and story all enter the same system, resurfacing when conditions allow. What appears after a storm is not new, but newly visible—a brief alignment of movement and exposure that allows what has long been present to be seen again.

The beach does not keep everything in sight. But it keeps everything, waiting for the moment the sand moves and the past becomes visible again.

The surface returns to quiet. The system does not. | Photo credit: A. Mitchell

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March 21, 2026