Helice tridens
Helice tridens is a species of crab which lives on mudflats around the coasts of Japan and the Korean Peninsula.
Ecology
It is semi-terrestrial, returning to the sea to spawn. The species appears to be adversely affected by the presence of raccoons, an invasive predator. H. tridens has a salinity requirement which lies between those of two other estuarine crabs in Japan, Helicana japonica and Chiromantes dehaani.Smaller individuals shelter in burrows in reed marshes, apparently in order to avoid cannibalism; this may also be the reason for the migration of larger individuals to brackish water lagoons in summer, when the crabs exceed their carrying capacity.