SANFORD, Christopher P.; Hofstra University, New York: Comparative Kinematic Analysis of a Novel Feeding Mechanism in Salmonid Fishes

Salmonid fishes possess a novel feeding mechanism that involves structural modification of the hyoid system. This tongue-bite apparatus of salmonids consists of a set of well-developed teeth on the dorsal surface of the anterior hyoid region and an opposing set of teeth on the roof of the mouth. This novel functional system is used in �raking� behavior to immobilize and shred prey following capture. In a study of three species of salmonids (the rainbow trout Oncorhynchus mykiss, brown trout Salmo trutta, and brook trout Salvelinus fontinalis), I used high-speed video (250 Hz) and frame-by-frame analysis to analyze the kinematic patterns of this novel feeding behavior. In spite of very similar structural features of the tongue-bite apparatus the kinematic patterns are different in all three species studied. From a discriminant function analysis the variables most important in distinguishing differences among species involved movements of the neurocranium, lower jaw and hyoid. The multivariate relationships of kinematic differences are congruent with the known phylogeny of the group. This supports the potential use of functional observations as additional characters with which to reconstruct phylogenies.