SANFORD, C. P.*; WAINWRIGHT, P. C. : Suction Feeding Performance in the Largemouth Bass Micropterus salmoides: Linking Buccal Cavity Kinematics using Sonomicrometry to Pressure

Suction feeding in fishes is the result of highly coordinated explosive expansion of the buccal cavity that results in the generation of subambient pressures. Buccal expansion draws water into the oral cavity through the mouth, quickly equalizing the buccal pressure. Larger subambient pressures generated in the oral cavity will generally result in a greater flow of water entering the mouth. On a theoretical level, the link between volumetric change and pressure change during suction feeding is well demonstrated. However, attempts to establish an empirical link between buccal kinematics and subambient pressure during suction feeding have met with only moderate success. In a study of feeding in largemouth bass we analyzed the relationship between suction pressure and simultaneous recordings of cranial movement based on sonomicrometric recordings from six crystals positioned inside the buccal cavity. From the positional relationship of these six crystals we were able to monitor the internal movements of the buccal cavity in both a mid?sagittal and transverse plane. We found that peak subambient pressure is reached very early in the kinematic expansion of the buccal cavity, and on average 24 ms before the first kinematic variable reaches its peak (gape). Using sonomicrometry we were able to consistently explain over 90% (and in the best models 99%) of the variation in buccal pressure using kinematics. Pressure changes in the buccal cavity during suction feeding are linked to several kinematic events and cannot be correlated with any single variable, or class of variable.