Meeting Abstract
10.10 Sunday, Jan. 4 Performance of Shark Teeth during Puncture and Draw: Implications for the Mechanics of Cutting WHITENACK, L.B.**; MOTTA, P.J.; Univ. of South Florida whitenac@mail.usf.edu
The performance of an organisms feeding apparatus has obvious implications for its fitness and survival. In this vein, a number of recent studies of elasmobranch functional morphology have specifically addressed feeding, though the role of teeth has largely been ignored. Here we report the results of performance testing of teeth in puncture, which mimics biting, and unidirectional draw, which mimics lateral head shaking behavior for ten species of extant shark and three extinct sharks. Teeth were mounted to a MTS 858 MiniBionix II universal testing system with a 5 kN load cell and moved through the prey item at 400 mm/s. For puncture teeth were tested on five prey items representing a range of material properties (Elops saurus, Haemulon plumieri, Archosargus probatocephalus, Sphyrna tiburo, Callinectes sapidus), and force to puncture, maximum puncture force, and energy to puncture were measured. Draw testing was limited to H. plumieri, and maximum force during draw was recorded. Overall, forces required for puncture were low, averaging 6.7 to 21.4 N for fish prey and 47.7 N for crab prey. Differences in puncturing performance occurred among different prey items and among tooth morphologies, though no discernable pattern was found for the latter. No differences in draw performance occurred among tooth morphologies. When considering both biological roles, the majority of the teeth did not perform better in puncture versus unidirectional draw. These results as well as an independent morphometric analysis do not support the functional classification of shark teeth as either tearing and cutting morphotypes suited for various prey types. These results have implications for studies of fossil chondrichthyans, where typically tooth morphology is used to predict feeding ecology in the absence of behavioral data.
