Laboratory Behaviour of Mosshead Sculpins Clinocottus Globiceps Toward Their Sea Anemone Prey

Abstract

Mosshead sculpins, Clinocottus globiceps, of the North American Pacific coast commonly feed upon sea anemones and in doing so make frequent body contact with the anemone tentacles. An attempt was made to determine if some sort of acclimation process, as seen in certain pomacentrid anemone fishes, is necessary for C. globiceps to engage in such repeated contacts. The laboratory experiments with C. globiceps and three species of anemones (Anthopleura xanthogrammica, A. elegantissima, Urticina crassicornis) revealed no obvious and consistent acclimatory behaviours by the fish toward anemones following a period of enforced isolation from anemones. Actions by C. globiceps toward anemones included frequent bites to tentacles, touches to tentacles without biting (whether intentional or not), and bites to the anemone's base or column. Tentacle bites occurred, on average, significantly earlier than tentacle touches in trials with Anthopleura elegantissima. There was no evidence that either tentacle bites or tentacle touches occurred earlier than the other in trials with A xanthogrammica and U. crassicornis. In paired trials where individualC. globiceps were tested first with A. xanthogrammica and then with U. crassicornis, the fish showed no significant difference in response to the two anemone species, either in the frequencies of different types of actions (bites or touches) or in the average order in which tentacle bites or tentacle touches occurred. Experiments were also conducted to compare the degree to which different sculpin species avoided contact with anemone (A. elegantissima) tentacles. Clinocottus globiceps seemed more tolerant of contact with tentacles than were the other sculpins, and only C. globiceps appeared intentionally to touch tentacles, sometimes leaning against or biting them.