BEHAVIORAL-RESPONSES OF HERMIT-CRABS TO SHELL CUES, PREDATOR HEMOLYMPH AND BODY ODOR

This study tested the hypothesis that predator odours alter behavioura l responses of hermit crabs to other chemical stimuli. Stimuli that ca use alarm and shell-related behaviour (hermit crab haemolymph and two gastropod flesh extracts), and stimuli that did not cause shell-relate d behaviour (sea-water and predator haemolymph) were used. Individual hermit crab responses to stimuli were observed in ambient sea-water an d predator odour. In the absence of predator odour, hermit crab haemol ymph and gastropod flesh extracts stimulated shell grasping behaviour. Locomotion was the major response to sea-water and stone crab haemoly mph. Crabs behaved consistently when repeatedly exposed to a particula r stimulus. In general, addition of predator odour to mixtures, result ed in decreased shell grasping and increased locomotion. Shell fit was a poor predictor of behaviour for the size range of crabs tested. Her mit crabs respond to, and discriminate, a variety of complex odour mix tures.