Meeting Abstract

76.4  Sunday, Jan. 6  Jaw protrusion increases the hydrodynamic forces suction feeding fishes exert on their prey HOLZMAN, R*; DAY, SW; MEHTA, RS; WAINWRIGHT, PC; Univ. of California, Davis; Rochester Inst. of Technology; Univ. of California, Davis; Univ. of California, Davis raholzman@ucdavis.edu

Jaw protrusion is a major innovation found in several groups of modern fishes. Unlike the fused upper jaws of more basal fish lineages and most tetrapods, the jaws of many living fishes are highly kinetic and connected to the braincase by a series of joints that enable their forward protrusion during feeding. Despite the prominence of jaw protrusion as a major axis of diversity in teleosts and widespread speculation about its role in trophic evolution, little is known about its mechanical consequences for feeding. We hypothesize that rapid forward protrusion of the oral jaws during suction generation can augment hydrodynamic forces exerted on the prey by increasing the acceleration of the fluid around the prey. Using a combination of a fluid mechanical model and empirical measurements of suction feeding centrarchid fishes, we show that protrusion enhances the force exerted on prey by up to 50% compared to slow-protruding and non-protruding jaws. Independent contrast analysis performed using a well-resolved phylogeny of centrarchid fishes indicates that the ability to produce strong suction pressure has evolved in association with the ability to quickly protrude the jaws toward the prey. This work suggests a substantial enhancement in suction feeding performance as a result of jaw protrusion and may provide a causal link between this innovation and the remarkable evolutionary success of jaw-protruding fish lineages.