Strike feeding behavior in the muskellunge, Esox masquinongy: Contributions of the lateral line and visual sensory systems

The muskellunge, Esox masquinongy, is a predatory esocid fish with well-dev eloped visual and lateral line systems, The purpose of this study was to de termine the relative roles of these two sensory modalities in organizing th e strike behavior of the animal. Subadult muskellunge were videotaped in a test arena while feeding on fathead minnows (Pimephales promelas). Animals were tested under five conditions: (i) control animals in which the visual and lateral line systems were intact; (ii) animals with lateral line affere nce suppressed by immersion for 12-24 h in 0.1 mmol l(-1) CoCl2; (iii) anim als blinded by bilateral optic nerve transection; (iv) animals that had bee n unilaterally blinded; and (v) animals in which the lateral line system ha d been unilaterally denervated. The feeding behavior of the muskellunge consists of two phases: a slow stal k of the prey with minimal body movement followed by an explosive C- or S-s tart lunge at the prey, Quantitative comparisons of animals in the five tes t groups indicate that, although vision is used in the initial acquisition of the prey, both vision and the lateral line system play important roles i n determining the initiation of the rapid strike. The lateral line system m ay play a critical role in the final capture of the prey at the end of the strike. In addition, lateral-line-suppressed muskellunge strongly alter the ir approaches to more distant prey. Bilaterally blinded muskellunge do not stalk their prey, but will lunge only at prey that are at close range. Unil aterally blinded or denervated muskellunge also alter their detection of an d approach to prey, attending to a wider region of the intact sensory hemis phere. Our data suggest not only that the visual and lateral line systems play com plementary roles in the feeding behavior sequence but also that each system plays a more or less dominant role during consecutive phases of the behavi or.