Helice tridens

Helice tridens is a species of crab which lives on mudflats around the coasts of Japan and the Korean Peninsula.^[3]

Helice tridens
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Malacostraca
Order:	Decapoda
Suborder:	Pleocyemata
Infraorder:	Brachyura
Family:	Varunidae
Genus:	Helice
Species:	H. tridens
Binomial name
Helice tridens (De Haan, 1835) [1]
Synonyms [2]
Ocypode tridens De Haan, 1835 Cyclograpsus latreillii H. Milne-Edwards, 1837 Helice latreillei H. Milne-Edwards, 1837

Ecology

It is semi-terrestrial, returning to the sea to spawn.^[4] The species appears to be adversely affected by the presence of raccoons (Procyon lotor), an invasive predator.^[4] H. tridens has a salinity requirement which lies between those of two other estuarine crabs in Japan, Helicana japonica and Chiromantes dehaani.^[5]

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.^[6]

Taxonomy

Helice tridens was first described by Wilhem de Haan in an 1835 volume of Fauna Japonica, as Ocypode tridens.^[7] The former subspecies H. t. wuana and H. t. sheni are now recognised as a separate species, Helicana wuana.^[2]