ONTOGENY OF COPEPOD PREDATION IN JUVENILE SQUID (LOLIGO-OPALESCENS)

Copepods are the major prey of juvenile squid, and small species of sq uid such as Loligo opalescens face a great challenge in catching these erratically moving crustaceans. We studied the ontogeny of copepod pr edation in laboratory-reared animals and found that mastery of copepod capture develops progressively, starting shortly after hatch with str ong attacks of a simple type. Modifications of the initial basic attac k lead to more specialized strategies that effectively extend the rang e of capture to both longer and shorter distances. This progression cu lminates, by approximately 40 days post-hatching, in adult-like prey c apture behavior involving tentacle extension and retraction. Squid rai sed exclusively on easily captured Artemia nauplii and introduced to a copepod diet 40 days after hatching displayed only basic attack behav ior, characteristic of very young squid. All of these attacks were uns uccessful, and very few of these animals survived the transition. Cope pod capture thus appears to be a skill that must be acquired in an exp erience-dependent manner early in post-hatching life.