2018 年 47 巻 p. 35-41
The social behaviors of crabs in the families Dotillidae and Macrophthalmidae inhabiting mangrove swamps in southern Thailand were observed in the field. The cheliped motion and duration of the waving display were determined for four dotillid crabs (Dotillopsis brevitarsis, Ilyoplax delsmani, Ilyoplax gangetica, and Ilyoplax orientalis) and two macrophthalmid crabs (Macrophthalmus erato and Macrophthalmus pacificus), and their motion patterns were compared with those of congeneric species. The sequential events of coupling by a male and a female were observed in D. brevitarsis, I. gangetica, and Ilyoplax obliqua. Fighting events were noted for D. brevitarsis, I. gangetica, I. obliqua, and M. erato. A threat display based on the vertical movement of the chelipeds was observed in the dotillid species Dotilla myctiroides. The chela-quivering display by male I. obliqua was described based on the cheliped motion and the context in which the display occurred.
