RICE, Aaron N.; WESTNEAT, Mark W.; Univ. of Chicago; Field Museum of Natural History: Coordination of Feeding and Locomotor Systems in the Labridae

To capture prey, fishes must coordinate complex movements of both the feeding and locomotor systems. Despite the extensive research on both systems in fishes, few studies have integrated these areas of study to explore one in the context of the other. We used high-speed digital video of feeding events of two predatory wrasses, Cheilinus fasciatus and Epibulus insidiator, and two herbivorous wrasses, Scarus vetula and Sparisoma radians, to ask: how do feeding and locomotion coordinate, and how does this coordination differ based on trophic strategy? Digitization of morphological landmarks from feeding events provided data on: linear and angular velocity and acceleration, fin movement, oculomotor movement, oral gape angle, and jaw protrusion. Predators have an increased number of fin beats to more precisely align themselves to the prey item and a relatively slower initial approach, whereas herbivores had a higher speed of approach with less adjustment of body orientation and a lower number of fin beats during approach to the prey. In Cheilinus, Epibulus and Scarus, jaw protrusion was immediately followed by a quick, forward braking stroke of the fins to prevent collision with the prey, whereas Sparisoma thrust forward during its biting strategy. Oculomotor data show that predators� eyes remained shifted forward upon the prey item, whereas herbivores� eyes were shifted laterally well before the contact with the food item. In summary, carnivore and herbivores showed differences in feeding and locomotor behavior that are consistent with differing prey. Biomechanics and neuromuscular activity during coordination of feeding may clarify the role of sensory systems in complex behavior and reveal patterns of differentiation and evolution of divergent trophic strategies in coral reef fishes.