Helice tridens

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Helice tridens
Helice tridens (Kohnoura).jpg
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
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

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


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]


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]


  1. ^ "Helice tridens". Crabs of Japan. Retrieved January 31, 2009. 
  2. ^ a b P. K. L. Ng, D. Guinot & P. J. F. Davie (2008). "Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world" (PDF). Raffles Bulletin of Zoology. 17: 1–286. Archived from the original (PDF) on 2011-06-06. 
  3. ^ Hsi-Te Shih & Hiroshi Suzuki (2008). "Taxonomy, phylogeny, and biogeography of the endemic mudflat crab Helice/Chasmagnathus complex (Crustacea: Brachyura: Varunidae) from East Asia" (PDF). Zoological Studies. 47 (1): 114–125. 
  4. ^ a b Hisayo Hayama, Masato Kaneda & Mayuh Tabata (2006). "Rapid range expansion of the feral raccoon (Procyon lotor) in Kanagawa Prefecture, Japan, and its impact on native organisms". In F. Koike; M. N. Clout; M. Kawamichi; M. De Poorter & K. Iwatsuki. Assessment and Control of Biological Invasion Risks (PDF). Shoukadoh Book Sellers, Kyoto, Japan and IUCN, Gland, Switzerland. pp. 196–199. 
  5. ^ Bambang Irawan & Akihiro Kijima (1994). "Difference of salinity requirements among the three estuarine crab species, Chiromantes dehaani, Helice tridens and H. japonica (Brachyura: Grapsidae)" (PDF). Tohoku Journal of Agricultural Research. 44 (1-4). 
  6. ^ Yasushi Kurihara, Katsuhiro Sekimoto & Masahide Miyata (1988). "Wandering behaviour of the mud-crab Helice tridens related to evasion of cannibalism" (PDF). Marine Ecology Progress Series. 49: 41–50. doi:10.3354/meps049041. 
  7. ^ Wilhem de Haan (1835). "Ocypode (Helice) tridens sp. nov.". In Philipp Franz von Siebold. Fauna Japonica. p. 57. 

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