Lateral line stimuli can override vision to determine sunfish strike trajectory

Although all fishes have a mechanosensory lateral line system — a system of water flow detectors (neuromasts) in canals or free on the skin’s surface — particular behavioral functions are documented for only a few species. Work on lateral line use for feeding has focused on either cavefishes or night-active species (Montgomery, 1989). While surface-feeding fishes with well-developed eyes do use the lateral line to locate prey (Müller and Schwartz, 1982), it is generally assumed that diurnal/crepuscular fishes are visual predators. We show that a hydromechanical stimulus detected by the cephalic lateral line system in two sunfishes (Centrarchidae) can be the sole determinant of a strike trajectory. The response occurs without reinforcement and appears to be an unconditioned response.