BEHAVIORAL INTERACTIONS BETWEEN THE ACTINIAN TEALIA-PISCIVORA (ANTHOZOA, ACTINIARIA) AND THE ASTEROID DERMASTERIAS-IMBRICATA

Interactions between the sea anemone Tealia piscivora and the sea star Dermasterias imbricata have been studied in the laboratory and in subtidal habitats. Dermasterias imbricata have been studied in the laboratory and in subtidal habitats. Dermasterias causes the release of the pedal disc of smaller T. piscivora. The response is specific. Nineteen other sea stars did not cause release; four other species of Tealia did not respond to Dermasterias. The response is size dependent; unfailing and quick in small T. piscivora, less frequent and slow T. piscivora, less frequent and slow in those of intermediate size, it did not occur at all in large specimens. Unrestrained T. piscivora generally survived interactions with Dermasterias but when prevented from detaching, most of the small anemones were devoured. Tealia piscivora have been observed to detach and engulf small Dermasterias. Most small anemones were found at greater depths; most large anemones were found at lesser depths where Dermasterias were most abundant. It is suggested that by releasing the pedal disc; small T. piscivora eventually end up in deeper water where there are few Dermasterias and thus the anemones escape predation.