Meeting Abstract

P3.97  Friday, Jan. 6  Muscle, shell, and tooth: a comprehensive investigation of durophagy in the cownose ray KOLMANN, Matthew A*; HUBER, Daniel R; DEAN, Mason; ERICKSON, Gregory M; GRUBBS, R Dean; Florida State University; University of Tampa; Max Planck Institute; Florida State University; Florida State University mkolmann@bio.fsu.edu

Durophagy is a feeding strategy which implies not only the ingestion of hard-shelled prey but also the dismantling of the prey carapace. The cownose ray, Rhinoptera bonasus, is a large coastal pelagic stingray thought to specialize on bivalves. Investigation of feeding performance in such an animal is particularly interesting in such that the ray’s skeletal structure is oftentimes much more compliant than the skeleton of its prey. Traditional morphometric analysis of jaw adductor muscle architecture coupled with physiological estimations of muscle forces have allowed development of a three dimensional static equilibrium model which calculates bite forces in cownose rays over their ontogeny. Live bivalve samples representing the ontogenetic and species diversity of cownose ray prey will be subjected to materials testing whereby the exoskeleton of the shellfish will be forced to failure. Failure events will be filmed at high speed and the wear patterns on the tooth plates of Rhinoptera will be characterized in order to qualitatively validate a normal loading regime during feeding. The forces at which shellfish valves exhibited failure will be compared to bite forces from Rhinoptera and used to determine the susceptibility of the prey to predation over the ontogenetic size range of both predator and prey. Preliminary data regarding bite force production in Rhinoptera over their ontogeny show force production spanning from 17 N in neonate animals to over 200 N in mature adults. An ecomorphological approach to this feeding system implies that typical predator-prey interactions are complicated by morphological considerations such as gape limitation, differential allometry of muscle forces, and skeletal component strength.