JANOVETZ, J.; Sweet Briar College: The Functional Morphology of Prey Capture in Serrasalmine Fishes

Despite being the characteristic method of feeding for a number of species-rich and ecologically important groups, the kinematics of biting prey capture in fishes have rarely been investigated. This study compares both biting and suction prey capture in three species of characin fishes from the subfamily serrasalminae; Piaractus brachypomus, a pacu, Metynnis argenteus, a silver dollar, and Pygocentrus nattereri, a piranha. These closely related species differ drastically in their natural diets, but all depend primarily on biting with the oral jaws to capture and process prey. All three species retain the ancestral ability to suction feed. The sequence and extent of cranial movements during suction feeding are within the range of values reported for other fishes during this behavior, although the time required for these movements is considerably longer in serrasalmines. Biting is a statistically distinct behavior from suction feeding in most measures of cranial movement and in the timing of these movements. Biting pieces from squid is characterized by a relatively large degree of cranial expansion in both Piaractus and Pygocentrus. Herbivorous bites on leaves in Piaractus and Metynnis, and squid biting in Metynnis, are characterized by relatively low displacement of cranial elements. Despite these differences in displacement, the timing of these movements is similar during both carnivorous and herbivorous bites. Biting is modulated according to differences in prey, but the extent to which strikes are modulated differs between the species in this study.