SANFORD, Christopher P.*; AJEMIAN, Matt J.; Hofstra University, New York; Hofstra University, New York: Evaluating the importance of new structures versus new muscle activity patterns in the evolution of a novel feeding mechanism in salmonid fishes.

Understanding how new functions evolve within the framework of a tightly integrated system has been one of the greatest challenges to evolutionary biology. Yet new functions are one of the most important mechanisms by which organisms can expand their potential niche and increase the likelihood of survival. Clearly identifiable examples are rare in which both the anatomical structures and muscle activation patterns have lead to new functions. The feeding mechanism of salmonid fishes represents an excellent case study in which to approach these issues in an integrative way. Salmonids possess a modified anterior hyoid, the �tongue bite� that consists of an impressive set of teeth on the surface of the bony tongue and an opposing set of teeth on the roof of the mouth. I will present the results of a kinematic and electromyographic study of feeding in the rainbow trout, Oncorhynchus mykiss. This tongue-bite system is used in a novel feeding behavior termed raking that is used to shred and disable prey following capture, and is distinct from other feeding behaviors analyzed. It is notable that when compared to the strike, differences in muscle activity pattern associated with this new raking behavior are relatively minor, primarily involving the jaw closing adductor manidbulae muscle. These minor changes have resulted in an entirely new feeding behavior that I predict have increased the feeding success of these fishes.