Meeting Abstract

67.4  Tuesday, Jan. 6  Feeding Biomechanics and Bite Force in bull sharks (Carcharhinus leucas) over ontogeny HABEGGER, M.L*; MOTTA, P.J; HUBER, D.R; University of South Florida; University of South Florida; University of Tampa mhabegge@mail.usf.edu

Bull sharks (Carcharhinus leucas) are one of the most aggressive coastal shark species inhabiting subtropical and tropical seas around the world. Several morphological characteristics such as a broad head, robust jaws, and large serrated teeth are obvious and notorious features of C. leucas, making this species an interesting model to study. Surprisingly, however, the feeding biomechanics of this species have not been investigated. The goal of this study is to describe the functional morphology of the jaw apparatus and investigate the ontogeny of bite performance in this top level predator. Theoretical calculations of jaw leverage and bite force were performed for an ontogenetic series of twenty individuals (73 to 258 cm TL) using a three dimensional static equilibrium model. Theoretical anterior bite force ranged from 36 to 1023 N, while theoretical posterior bite force ranged from 170 to 3720 N. Mechanical advantage at the anterior teeth ranged from 0.2 to 0.3 and at the posterior teeth from 1 to 1.2 over ontogeny, characterizing this species with a forceful jaw. Absolute values of bite force increased exponentially, with an abrupt increase in animals above 120 cm TL. Although their feeding ecology is not well known, dietary literature suggests that bull sharks exhibit an ontogenetic dietary shift from bony fishes to elasmobranchs and mammals at approximately 140 cm TL. This dietary data correspond with our results suggesting that animals above 120 cm TL may be more capable of processing harder and/or larger prey. Studying bite force, as a measurement of performance, can provide a better understanding of the feeding ecology and foraging capabilities of this apex predator over ontogeny.