The behavior ofDardanus arrosorin association withCailiactis parasiticain artificial habitat

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Abstract
In the artificial habitat of an aquarium specimens of hermit crabs carrying commensal sea anemones gradually lose their anemones, surprisingly because the crabs frequently damage or eat them. On the Mediterranean association Dardanus arrosor and Calliactis parasitica, the influence of feeding, of population density, or the activity of Dardanus towards Calliactis, and the presence or absence of a predator, were investigated as possible factors responsible for the disappearance of the anemone and the anomalous behavior of the crabs. Both lack of food and high population density increased the numbers of anemones that disappeared. It was noted that these artificial conditions probably do not occur in the natural habitat. All freshly collected Dardanus (both sexes), and presumably all Dardanus in their natural habitat, are active in acquiring Calliactis but during 4–5 months in the aquarium most of this activity is lost. In the presence of a probable predator, the octopus Eledone, these inactive crabs become active again in transferring anemones to their shells. This suggests that predation in the natural habitat is one of the factors responsible for the activity of the crab in acquiring anemones, at least in the association between Dardanus arrosor and Calliactis parasitica.