FOUGEROLLE, M.F.*; TURINGAN, R.G: The effects of prey type on the feeding biomechanics of Archosargus probatocephalus.

Ubiquitous species in heterogeneous, coastal habitats typically encounter variable prey-resources. The biomechanical basis for the ability of A. probatocephalus to consume both soft and hard prey organisms within its environment was examined in an attempt to understand the mechanisms that underlie the abundance and distribution of this species. Fish from the same location within the Indian River Lagoon were reared under two diets: whole bean clams (Donax gouldii) [hard prey] and D. gouldii with shells removed (soft prey). At the end of a 70-day rearing period, fish were measured for key biomechanical features of the prey-capture and processing mechanism. Analysis of Covariance revealed that biting muscles and bones of fish fed hard prey were more massive than fish fed soft prey. For a given body size, estimated biting strength of fish reared in hard-prey diet was greater than fish reared in soft-prey diet. Total body mass and mechanical advantage of the feeding mechanism did not differ between diet treatments. We hypothesize that the ability of A. probatocephalus to consume different prey organisms is associated with its ability to alter the development of its feeding mechanism. Phenotypic plasticity appears to be one of the mechanisms that underlie a species ability to exploit locally available prey-resource.