SEASONALITY OF REPRODUCTIVE ACTIVITY IN ILYOPLAX PUSILLA(BRACHYURA : OCYPODIDAE)

Abstract

Field study of reproductive activity in the ocypodid crab Ilyoplax pusilla was carried out at Tanabe Bay (33°41′N, 135°24′ E). Ovigerous females were found from April through August and most abundant in June-July. Males' sexual behaviors were observed from May through July or August and most frequent in June-July. Females were suggested to spawn or release their larvae around spring tide. Daily frequency of males' sexual behaviors did not fluctuate according to tidal condition of spring to neap tides. Proportions of waving males and wandering crabs declined in the late breeding to the nonbreeding season, indicating relation of waving and wandering to reproductive activity.