Comparison of social behaviors among six grapsoid species (Brachyura) of different habitat conditions

摘要

Social behaviors were observed in the field for six grapsoid crabs living under different habitat conditions from exposed to sheltered conditions, i.e. Helice tridens, H. japonica, H. leachi, Chasmagnathus convexus of the family Varunidae, and Chiromantes dehaani, and Perisesarma bidens of the family Sesarmidae. Fighting behaviors in these six species, cheliped-displays in H. tridens, H. japonica and P. bidens, and copulatory behaviors in H. tridens, C. dehaani and P. bidens were described. Elementsof fighting behavior varied among species irrespective of taxonomic group. The three species that showed cheliped-displays occurred in more exposed habitats compared to the other species, suggesting the importance of habitat conditions in the evolution of such displays. Copulatory behaviors were observed in three species, but precopulatory courtship was absent.