Ecological Morphology of Shark Teeth

Morphology, the structure and form of an organism, has often been used to infer an animal’s ecology since the performance and behavioral application of different structures can constrain movement and feeding. Sharks are well known for their many rows of teeth and wide variety of shapes and sizes, but less is known about how tooth shape varies over ontogeny (growth and development). Additionally, the extent of differences in tooth shape within a single set of shark jaws has widely gone untested. Since these differences in tooth shape within a single jaw or over ontogeny can have implications for feeding performance and energy expenditure, the tooth morphology of bull (Carcharhinus leucas), blacktip (Carcharhinus limbatus), and bonnethead sharks (Sphyrna tiburo) were analyzed since they are known to undergo ontogenetic dietary shifts and each feed on different types of prey.

Significant differences in tooth morphology were only observed in bull sharks at four different positions (of six) tested. However, only one of these appears to have any functional differences in shape over ontogeny. When comparing tooth morphology throughout the jaws of each species, bull sharks exhibited the greatest heterodonty. A comparison of teeth at each jaw position among all three species found significant differences at all but two positions (where bull and blacktips were similar). These findings support the generalist feeding strategy of bull sharks that may need a greater variety of tooth shapes to process prey with different material properties. Blacktip and bonnethead sharks had much less heterodonty throughout their jaws, indicative of specialists on fish and crustaceans, respectively. It is possible that the tooth morphology of each species may confer an increased net energy intake with teeth that are well suited to process certain types of prey than other types of prey those species typically do not consume.

Published work on this topic can be found here.

Josh Cullen, PhD
Josh Cullen, PhD
NSF Postdoctoral Research Fellow

My research interests include animal movement ecology, Bayesian modeling, and R stats.