Meeting Abstract

P2-108   -   Chomping at the bit: the effects of wear on shark tooth puncture performance and morphology Sesler, R; Whitenack, LB*; Allegheny College, Meadville, PA; Allegheny College, Meadville, PA lwhitena@allegheny.edu https://sites.google.com/a/allegheny.edu/whitenack/

Sharks replace their teeth regularly, producing thousands of teeth in their lifetime. However, previous work has shown that shark teeth are structurally strong under biologically relevant loading conditions, suggesting the frequent replacement of teeth is not likely due to tooth breakage. Instead, the frequency of replacement may be due to tooth wear, rather than tooth failure. As the tooth tip and edges wear, the surface area of these features increases, which should lead to less stress produced by the tooth during a bite and more force required to puncture the prey item. Our aim is to analyze the impact that wear holds on puncture performance and tooth morphology. For our preliminary experiment, serrated teeth from three species were utilized: Carcharhinus plumbeus, C. leucas, and C. limbatus. Each tooth punctured a fish prey item 400 times. Force was measured every 10 to 30 punctures, followed by photographing the tooth tip and cutting edges through a dissection microscope at each interval. We found that over 400 punctures, tooth wear occurs and force to puncture increases. The radius of curvature of the tooth apex increases by 5.8 to 9.9 microns, while the serrations decrease in height by 0.1 to 0.8 microns and the radius of curvature increases by 0.1 to 2.0 microns. The rate of wear in each location varies, as some serrations wear at an increased rate when compared to adjacent serrations. As the tooth wears, forces increase by 10.6 to 19.1 N, depending on the species. In a more dramatic example, one C. plumbeus tooth tip broke midway through the trials. The tooth apex radius of curvature went from 6.3 microns to 47.9 microns, while the puncture force increased from 6.2 to 47.9 N. While all of these forces are below the bite forces of the species measured to date, these preliminary results suggest that even small amounts of wear may affect tooth performance.