Orientation of Coenobita rugosus (Crustacea: Anomura): A field study on Aldabra

Experiments were designed to determine whether anemotaxis shown by the terrestrial hermit crab Coenobita rugosus H. Milne Edwards is (i) an orientational strategy leading the crabs to sea or (ii) a strategy improving rectilinear flight. In an arena with uniform landscape, hermit crabs from different beaches of the Aldabra atoll orientated during daylight in the direction of the sea of their own beach; this orientation was only slightly affected by wind direction. Under artificial wind conditions, at night, all hermit crabs displayed positive anemotaxis, independent of the orientation of the home beach, thus leaving little support for the first hypothesis. During the day, with the sea and beach both visible, all the hermit crabs on the beach moved landwards irrespective of wind and home beach direction.