Abstract
Population structures and reproductive activities of two intertidal ocypodid crabs, Ilyoplax pingi and I. dentimerosa, were compared at Kanghwa Island, western Korea. Density at abundantly populated area was higher in I. pingi (mean = 238 per m^2) than in I. dentimerosa (159 per m^2). Ovigerous females of I. pingi occurred from May to August, with the peak in August, resembling other temperate ocypodids, whereas females of I. dentimerosa brooded from April to August, with the marked peak in April. Females of both species appear to commence breeding at age of 1 year. Female I. dentimerosa carried eggs of larger size (mean = 0.3753 mm × 0.3543 mm) and smaller number (mean = 1136 eggs) than female I. pingi (0.2869 mm × 0.2725 mm, 2192 eggs). Pair formation of both species was completed by entry of the male and the female into the same burrow; in I. pingi the female usually entered the male's burrow, while the reverse case occurred more often in I. dentimerosa.
