Sharks of Onslow County
Shark teeth aren’t just pointy souvenirs—they’re precision tools evolved over millions of years to match each shark’s preferred prey. In Onslow County, North Carolina, our coastal waters are home to a variety of shark species, each with teeth designed for specific feeding strategies and a story to tell. By looking closely at tooth shape, size, and serration, you can often identify which shark it came from and what it was built to eat.
Each shark tooth is made up of several specialized parts:
Traditionally, these structures have been celebrated as one of nature’s most effective feeding tools (Whitenack & Motta, 2010). However, new studies show they are increasingly vulnerable to environmental change.
Recent experiments simulating rising pH from increasing CO₂ emissions or ocean acidification— has revealed that it directly corrodes shark teeth. In laboratory tests, blacktip reef shark (Carcharhinus melanopterus) teeth placed in simulated future ocean conditions (pH 7.3) showed severe corrosion after just eight weeks. Damage included cracks, holes, loss of serrations, and weakened crowns (Baum et al., 2025). Media reports confirmed that acidified conditions caused up to 50% more deterioration compared to present-day seawater (Carrington, 2025; Sample, 2025).
Although sharks can continually replace their teeth, researchers warn that weaker, more brittle teeth increase energetic costs for replacement and may lower hunting efficiency (Baum et al., 2025). Even apex predators may face feeding challenges if climate-driven acidification continues to progress.
| Tooth Type | Likely Shark Species | Prey Preference |
| Broad, serrated triangle | Bull shark, sandbar shark | Fish, turtles, rays |
| Slender, pointed | Blacktip, spinner | Baitfish |
| Flat, rounded | Bonnethead (rear teeth) | Crustaceans, mollusks |
| Notched, curved | Tiger shark | Variety – fish, shellfish, carrion |
Onslow Bay is also famous for fossil shark teeth, including Otodus megalodon and Otodus chubutensis. Many fossil teeth recovered offshore show borings from invertebrates, evidence of how these giant teeth became part of seafloor lag deposits (Maisch et al., 2019).
Tooth form reflects diet: needle-like teeth for baitfish, serrated triangles for larger prey, and molariform crushers for shelled invertebrates. This functional diversity is critical to shark ecology, and new threats like acidification highlight how even small changes to tooth integrity could alter feeding success (Baum et al., 2025; Corn et al., 2016).
This video will walk you through shark anatomy, crown vs. root, serrations, and how tooth shape maps to diet. You can apply those cues to common Onslow County species.
Direct link: Watch on YouTube: https://www.youtube.com/watch?v=TV6g8BMiImM
Not every tooth you find along the shore tells the same story. Some were shed by a living shark just days or weeks ago, while others are relics from ancient seas.
Though the sediment’s mineral content is a major driver, color patterns can get complex:
On the beaches of Topsail, Emerald Isle, and Bear Island (Hammocks Beach State Park), collectors may find fossilized teeth spanning extinct and modern lineages:
Onslow Bay’s Miocene–Pliocene sedimentary deposits make it a rich source of permineralized shark teeth—and the colors seen reflect the local sediment chemistry (e.g., phosphate vs. iron-rich layers) rather than the teeth’s exact age (FossilGuy.com, n.d.; Maisch et al., 2019). Many fossil hunters prize these finds not only for their form and rarity but also for the geological story encapsulated in their hues.
Shark teeth can be found along the beach and come in all sizes and colors. Some are so tiny that they can only be seen by close examination of the sand or even under the microscope!
Every shark tooth found in Onslow County tells a story—of predator and prey, adaptation, and even global climate change. By learning how form meets function, we not only identify species but also glimpse the pressures shaping their survival today.
Baum, M., Haussecker, T., Walenciak, O., Köhler, S., Bridges, C. R., & Fraune, S. (2025). Simulated ocean acidification affects shark tooth morphology. Frontiers in Marine Science, 12, 1597592. https://doi.org/10.3389/fmars.2025.1597592
Carrington, D. (2025, August 27). Toothless sharks? Ocean acidification could erode predator’s vital weapon, study finds. The Guardian. https://www.theguardian.com/environment/2025/aug/27/ocean-acidification-erodes-sharks-teeth-affecting-feeding
Corn, K. A., Farina, S. C., Brash, J., Summers, A. P., & Kolmann, M. A. (2016). Modeling tooth–prey interactions in sharks: The importance of dynamic testing. Royal Society Open Science, 3(5), 160141. https://doi.org/10.1098/rsos.160141
FossilGuy.com. (n.d.). Why are fossil shark teeth different colors? An explanation of why fossils are different colors. Retrieved September 1, 2025, from https://www.fossilguy.com/topics/shark-teeth-colors/index.htm
Goodman, K., Goldbogen, J. A., & Bizzarro, J. J. (2022). Ontogenetic changes in the tooth morphology of bull sharks (Carcharhinus leucas). Journal of Fish Biology, 101(6), 1396–1408. https://doi.org/10.1111/jfb.15181
Höltke, O. (2024). A review of the paleobiology of some Neogene sharks. Diversity, 16(3), 147. https://doi.org/10.3390/d16030147
Maisch, H. M. IV, Becker, M. A., & Chamberlain, J. A. Jr. (2019). Macroborings in Otodus megalodon and Otodus chubutensis shark teeth from the submerged shelf of Onslow Bay, North Carolina, USA. Ichnos, 26(4), 377–388. https://doi.org/10.1080/10420940.2019.1693755
Sample, I. (2025, August 27). How ocean acidification is taking the bite out of sharks’ teeth. The Times. https://www.thetimes.co.uk/article/ocean-acidification-corrodes-shark-teeth-fk985lnw7
Whitenack, L. B., & Motta, P. J. (2010). Performance of shark teeth during puncture and draw: Implications for the mechanics of cutting. Journal of Morphology, 271(3), 469–479. https://doi.org/10.1002/jmor.10809
