Acoustic calling and the mechanisms of its production are described or the ghost crabs Ocypode jousseaumei, O . platytarsus, O. rotundata, and O. saratan from Oman. Sounds generated by the major cheliped suggest the existence of species specific differences, predominantly in the temporal properties of rapping and in the physical structure of stridulation. The spectral energy of all sounds is concentrated at frequencies below 4 kHz. O. rotundata and O. saratan build sand pyramids adjacent to their courtship burrows and are considerably less acoustically active than O. jousseaumei and O. platytarsus that do not build pyramids, suggesting that the visual signal is substituted by an auditory one.
acoustic calling, Ocypode, rapping, stridulation