Abstract
The habitats, nest burrows, hibernation, awaking, molting, copulation. oviposition, egg-bearing, zoea-liberation (spawning) , beach landing of the tiny young, and so on of the land-crab, Sesarma (Holometopus) haematocheir (DE HAAN), were studied from April, 1979 to November, 1980. Field observation was made in the rocky shore near the Sado Marine Biological Station of Niigata University located on the west coast of Sado Island in the Japan Sea. When the ground temperature (GT) fell gradually 16℃, the crabs emerged from the nest and went to the beach for feeding. Molting occurred from late June to middle September, although in mother crab it took place since August after the release of zoeal larvae. Copulation was found from late June to early August, and the frequency of copulation and next oviposition in one spawning season were two to three times per crab. Zoea release took place almost every night about one or two hours after sunset (ca. 19:00) during the period from late July to early September, although no spawning was encountered in stormy weather. Beach landing of an infant crab just metamorphosed from megalopa was seen in late September, and the first molting occurred in a pool two or three days after landing. Difference between the spawning behavior of this land-crab occurring in the Japan Sea coast and in the Pacific coast was discussed in relation to the difference of the tidal changes in the both coasts.
