Morphological basis of kinematic diversity in feeding sunfishes

The effects of differences among species in the scaling of lower jaw levers on the scaling of prey-capture kinematics are explored in three species of centrarchid fishes. We consider the jam opening and closing lever systems and calculate the consequences of differences in the scaling of the in-leve rs for the scaling of the time taken to open the mouth (T-o) and the time t aken to close the mouth (T-c) during prey capture. Predictions of T-o and T -c, based on differences in the scaling of jaw in-levers, are compared with the observed scaling of T-o and T-e in three centrarchid fishes, Video rec ordings (200 and 400 images s(-1)) were made of prey capture in largemouth bass Micropterus salmoides (33-206 mm standard length, SL), spotted sunfish Lepomis punctatus (24-145 mm SL) and bluegill sunfish Lepomis macrochirus (24-220 mm SL), and the fastest values of T-o and T-c were taken from the f astest recorded feeding event for each fish. The scaling exponents of T-o a nd T-c regressed on fish SL for largemouth bass were 0.592 and T-c regresse d on fish SL for largemouth bass were 0.592 and 0.572, respectively. Expone nts observed for sunfishes were not significantly different from predicted values, based on scaling exponents in largemouth bass and interspecific dif ferences in jam lever proportions. Two conclusions are emphasized. First, b etween 25 and 220 mm SL, the time taken to open and close the mouth during the strike increases with body size in all three species, suggesting a gene ral pattern for this family. Second, evolutionary changes in jaw lever mech anics are a major determinant of the diversity of prey-capture kinematics i n this sample of centrarchid fishes.