MILLER, T.*; CARRENO, C. A.; FERRY-GRAHAM, L. A.; O’NEILL, M. W.; GIBB, A. C.; Ashland University; Northern Arizona University; California State University; Northern Arizona University; Northern Arizona University: Performance ramifications of premaxillary protrusion: buccal pressure and capture success in small mouth bass with immobile premaxillae

Teleosts are the most successful group of aquatic vertebrates and most of these fishes use suction feeding to capture prey. Upper jaw protrusion (premaxillary protrusion) is thought to enhance suction production by increasing the volume of the buccal cavity and decreasing the mouth diameter, thus increasing the overall pressure change inside the head and increasing the velocity of water as it moves into the mouth. We used smallmouth bass (Micropterus dolomieu) as a model system because they exhibit premaxillary protrusion and produce suction in the buccal cavity during prey capture. We predicted that the loss of premaxillary protrusion would result in a decrease in suction generation and prey capture success. In this experiment, a pressure transducer was inserted into the buccal cavity of a smallmouth bass to record pressure changes during prey capture. After recording baseline feeding pressures, one half of the individuals had their premaxilla surgically sutured to the maxilla to prevent premaxillary protrusion. The other half of the individuals received a sham surgery that consisted of tying suture around the premaxilla without attaching it to the maxilla. During all feeding events, simultaneous digital images were recorded to measure feeding events. Our preliminary results suggest that fish with no premaxillary protrusion (i.e., fish with surgically restricted premaxillae) produce less suction and have reduced prey capture success relative to unmanipulated fish or fish that received a sham surgery. These results support the general hypothesis that premaxillary protrusion enhances suction feeding performance in teleost fishes.