Interrelation of Feeding Behavior and Accommodative Lens Movements in Some Species of North American Freshwater Fishes

Abstract

Accommodation, in response to atropine and pilocarpine, was measured retinoscopically and photographically in seven species of freshwater fishes. These species accommodate in varying magnitudes and directions by means of lenticular movements. The common white sucker (Catostomus commersoni) and the goldfish (Carassius auratus) accommodate mainly in the lateral direction (5–10 diopters), whereas the common bluegill (Lepomis macrochirus), northern rock bass (Ambloplites rupestris), and yellow perch (Perca flavescens), exhibit a larger accommodative ability which occurs primarily along the rostral–caudal axis (up to 40 diopters in the yellow perch). The rainbow trout (Salmo gairdneri) accommodates equally along the lateral and rostral–caudal axes. No accommodative response occurs in the northern black bullhead (Ictalurus melas). Reference to the diets and feeding habits of the above species suggests that the magnitude and principal direction of accommodation is a response to the visual demands of a particular life history.