BEHAVIORAL MECHANISMS OF PREY SELECTION IN CRABS

Laboratory experiments were designed to investigate key stimuli used b y blue crabs, Callinectes sapidus, when selecting prey. Results were c ompared with behaviour predicted, or assumed, by optimal foraging theo ry. Both live prey and simple models were employed to monitor the resp onses of blue crabs foraging either in tactile mode, as when feeding o n marsh mussels, Geukensia demissa, attached to the substratum, or in visual mode, as when foraging on fiddler crabs, Uca spp., moving over the substratum. We suggest that foraging blue crabs simply respond to the strongest stimuli received from the prey. Items are rejected after a certain persistence time if the attack is proving unsuccessful. Per sistence time is adjusted, through experience, to expectations of loca l prey quality or availability. The integrated result of this key-stim ulus mechanism of prey selection will be a close match to diets predic ted by other behavioural models, including that based on optimal forag ing theory.