Substrate (acoustic/vibrational) communication and ecology of the ghost rab Ocypode jousseaumei (Brachyura: Ocypodidae)

Abstract

Semi-terrestrial ghost crabs, Ocypode jousseaumei, are active on sheltered beaches at low tide. Each tidal cycle, males construct courtship burrows that spiral according to the handedness of the crab's major chela. Burrows are over-dispersed since residents prevent other crabs from excavating burrows too close and some emerging crabs abandon their burrows. Other wandering crabs may enter courtship burrows eliciting threatening displays or fights which are more severe in like-handed crab social interactions. Sometimes residents are evicted. The details of vibrational/acoustic signalling of male O. jousseaumei are reported, including the first complete description of stridulation. The approach of crabs of any species or sex elicits increased rapping behaviour by residents, but close passage or entry elicits stridulation from within the burrow. Rapping is probably a signal to advertise residents’ location while stridulation is used for burrow defence. It is probable that male crabs’ vibrational/acoustic signalling is also influenced by that of neighbours.