Movement as a necessary stimulus of Octopus predation.

Abstract

IT is usually supposed that movement is a necessary stimulus to initiate the attack of Octopus vulgaris on a crab and, for example, Boycott and Young say1 that “this movement is absolutely necessary; a crab which remains still, even in full view of an octopus, is not attacked”. In many experiments, the presentation of stimuli has been based on this conclusion; the stimuli were moved to attract the octopus2,3. My observations indicate, however, that O. vulgaris frequently attacks crabs which are not moving at the time and for some time before.