INTRASPECIFIC AGGRESSION AND ITS EFFECT ON THE DISTRIBUTION OF ANTHOPLEURA ELEGANTISSIMA AND SOME RELATED SEA ANEMONES.

Abstract

Contiguous aggregations of the west coast sea anemone Anthopleura elegan tissima are composed of individuals from a single clone, the products of asexual reproduction. In the field, adjacent clones of anemones are observed to be iso lated from each other by anemone-free spaces ; and in the laboratory a group of anemones of mixed clonal origins will reaggregate into isolated uniclonal groups. (Francis, 1973) . In the field I have also observed that individuals of the large solitary form of Anthopleura elegantissima also remain isolated from adjacent members of the species. Contacts between genetically different individuals of this species initiates in one or both individuals an elaborate behavior pattern that usually results in damage to one or both animals. This is aggressive behavior according to the definition of Carthy and Ebling ( 1964) , “?�An animal acts aggres sively when it inflicts, attempts to inflict, or threatens to inflict damage on another animal. The act is accompanied by recognizable behavioral symptoms and de finable physiological changes” (page 1 ) . This behavior has never before been reported for this species, and my purpose here is to describe this specialized aggres sive behavior and to investigate the relationship between the aggressive behavior of this and related species and the observed field distributions.