AN ANALYSIS OF THE DEFENSIVE MECHANISMS OBSERVED IN THE ANEMONEANTHOPLEURA ELEGANTISSIMAIN RESPONSE TO ITS NUDIBRANCH PREDATORAEOLIDIA PAPILLOSA

Abstract

1. The defensive mechanisms shown by the west coast, intertidal sea anemone, Anthopleura elegantissima, in response to its nudibranch predator Aeolidia papillosa are identified and evaluated in the context of the environment where A. elegantissima occurs. The defensive mechanisms include intertidal distribution, clone formation, alarm response, bulging of the column, crawling and releasing from the substrate.2. A. papillosa are primarily located at the periphery of clones so that anemones in the interior of the clone have a refuge from predation. Assuming that cloning is an adaptation for space competition in A. elegantissima, then the additional advantage derived as a defensive mechanism should increase selection for clone formation.3. A. papillosa was less able than A. elegantissima to withstand desiccation from exposure at low tide. This suggests that the intertidal distribution of A. elegantissima is a defensive adaptation which reduces the threat of predation by A. papillosa at least during the warme...