Behavioural Responses of Hermit Crabs to Shell Cues, Predator Haemolymph And Body Odour

Abstract

This study tested the hypothesis that predator odours alter behavioural responses of hermit crabs to other chemical stimuli. Stimuli that cause alarm and shell-related behaviour (hermit crab haemolymph and two gastropod flesh extracts), and stimuli that did not cause shell-related behaviour (sea-water and predator haemolymph) were used. Individual hermit crab responses to stimuli were observed in ambient sea-water and predator odour. In the absence of predator odour, hermit crab haemolymph and gastropod flesh extracts stimulated shell grasping behaviour. Locomotion was the major response to sea-water and stone crab haemolymph. Crabs behaved consistently when repeatedly exposed to a particular stimulus. In general, addition of predator odour to mixtures, resulted in decreased shell grasping and increased locomotion. Shell fit was a poor predictor of behaviour for the size range of crabs tested. Hermit crabs respond to, and discriminate, a variety of complex odour mixtures.