82.1 Monday, Jan. 6 10:30 Comparison of cranial and axial muscle power for suction feeding in largemouth bass CAMP, A.L.*; ROBERTS, T.J.; BRAINERD, E.L.; Brown University, Providence RI; Brown University, Providence RI; Brown University, Providence RI email@example.com
Suction feeding relies on substantial muscle power to expand the mouth cavity so that volume increases, pressure decreases, and water and prey are accelerated inside. The power for suction expansion must be generated by muscles, but we know little about how much power is required and the relative contributions of cranial and axial muscles. All actively shortening muscles generate some power, but the magnitude depends on a muscle’s mass, activation, and shortening velocity. Both cranial and axial muscles have the appropriate attachments to generate mouth expansion, but the cranial muscles have been hypothesized to be too small to power this motion. We calculated the total power generated during mouth expansion, and compared it to the power each cranial and axial muscle is capable of producing. To calculate suction expansion power, we measured pressure and volume change of the mouth cavity during suction feeding strikes in largemouth bass (Micropterus salmoides). The maximum power output of each axial (epaxial, hypaxial) and cranial (levator operculi, dilator operculi, sternohyoid, levator arcus palatini) muscle was calculated from measurements of mass and in vivo shortening velocity. The cranial muscles together could not produce the power required for suction expansion, even assuming optimal activation and shortening velocity. However, the axial muscles were capable of substantial power production, exceeding that required for suction expansion. This was true even when non-optimal (i.e., in vivo) shortening velocities were considered. The relatively small size of the cranial muscles limits their ability to generate power for feeding. Fish appear to use much of their massive body muscles to provide the power required for suction feeding.