Behavioral choice and habituation in the marine mollusk Pleurobranchaea californica MacFarland (Gastropoda, Opisthobranchia)

Abstract

1. Complex behavior in the carnivorous marine gastropod Pleurobranchaea californica is described (Figs. 1–6). 2. Situations requiring behavioral choice can be created by simultaneously delivering the stimuli for two different behavior patterns. In such situations feeding is elicited in preference to other behaviors, including sexual activity and righting responses. 3. Two behaviors have been examined in detail, the withdrawal response to light and feeding. The withdrawal response habituates; correlated studies on the nervous system showed that the habituation has two causes, adaptation of the visual response (Figs. 8, 9) and habituation of the participating central pathways (Figs. 10–12). The central habituation is specific to pathways involving the visual input. Neuromuscular adaptation is not involved in the behavioral habituation. 4. The sequence of muscular activity causing the rhythmic feeding movements was determined by cinematography (Fig. 14) as well as anatomical (Fig. 15) and electromyographic (Figs. 16, 17) methods. Central nerve cells were located which either excite or inhibit efferent outflow to the feeding apparatus (Figs. 21, 22).