Abstract
A study of behaviour of certain organisms displaying avoidance reactions to sea stars was part of an investigation to determine the substances responsible for such reactions. Research during 1964–65 in Scandinavian and British coastal areas focused on the reactions of 13 gastropod molluscs, 3 lamellibranch molluscs and 1 sea star following asteroid contact and suggested the possible adaptive significance of these responses. Sea stars used were Marthasterias glacialis, Asterias rubens, Crossaster papposus, Solaster endeca, and Asterina gibbosa. Although most recorded observations have been from temperate waters, a few observations suggest that avoidance behaviour to sea-star presence or contact is a world-wide phenomenon. Types of movements resulting from asteroid contact varied, but similarities were detected in related genera.