Hydrodynamics of Prey Capture by Teleost Fishes

Abstract

The dominant mode of prey capture in teleost fishes is inertial suction: rapid expansion of the mouth cavity creates a negative (suction) pressure relative to the surrounding water. This pressure differential results in a flow of water into the mouth cavity carrying in the prey. Previous models of the suction feeding process have predicted the pattern and magnitude of pressure change in the mouth cavity based on kinematic profiles of jaw bone movement and the application of the Bernoulli equation and the Hagen-Poiseuille relation. These models predict similar pressure magnitudes and waveforms in both the buccal and opercular cavities, and rely on the assumption of a unidirectional steady flow. In vivo simultaneous measurement of buccal and opercular cavity pressures during feeding in sunfishes shows that (1) opercular cavity pressures average one-fifth buccal pressures (which may reach −650 cm H20),(2) the opercular and buccal cavities are functionally separate with distinct pressure waveforms, (3) a flow reversal (opercular to buccal flow) probably occurs during mouth opening, and (4) the kinetic energy of the water and inertial effects must be considered in hydrodynamic models of suction feeding.