Helice tridens explained

Helice tridens is a species of crab which lives on mudflats around the coasts of Japan and the Korean Peninsula.^[1]

Ecology

It is semi-terrestrial, returning to the sea to spawn.^[2] The species appears to be adversely affected by the presence of raccoons (Procyon lotor), an invasive predator.^[2] H. tridens has a salinity requirement which lies between those of two other estuarine crabs in Japan, Helicana japonica and Chiromantes dehaani.^[3]

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.^[4]

Taxonomy

Helice tridens was first described by Wilhem de Haan in an 1835 volume of Fauna Japonica, as Ocypode tridens.^[5] The former subspecies H. t. wuana and H. t. sheni are now recognised as a separate species, Helicana wuana.

Notes and References

1. . Taxonomy, phylogeny, and biogeography of the endemic mudflat crab Helice/Chasmagnathus complex (Crustacea: Brachyura: Varunidae) from East Asia . Hsi-Te Shih . Hiroshi Suzuki . amp . 47 . 1 . 114–125 . 2008 . 2010-03-27 . 2017-08-09 . https://web.archive.org/web/20170809075913/http://zoolstud.sinica.edu.tw/Journals/47.1/114.pdf . dead .
2. Book: Rapid range expansion of the feral raccoon (Procyon lotor) in Kanagawa Prefecture, Japan, and its impact on native organisms . Hisayo Hayama, Masato Kaneda . Mayuh Tabata . amp . 196–199 . F. Koike . M. N. Clout . M. Kawamichi . M. De Poorter . K. Iwatsuki . Assessment and Control of Biological Invasion Risks . Shoukadoh Book Sellers, Kyoto, Japan and IUCN, Gland, Switzerland . 2006 . 2009-01-31 . https://web.archive.org/web/20110722080721/http://vege1.kan.ynu.ac.jp/isp/pdf/Hayama_et_al.pdf . 2011-07-22 . dead .
3. . 44 . 1–4 . 1994 . Difference of salinity requirements among the three estuarine crab species, Chiromantes dehaani, Helice tridens and H. japonica (Brachyura: Grapsidae) . Bambang Irawan . Akihiro Kijima . amp . 2009-01-31 . https://web.archive.org/web/20120602075333/http://ir.library.tohoku.ac.jp/re/bitstream/10097/29948/1/KJ00000715049.pdf . 2012-06-02 . dead .
4. Wandering behaviour of the mud-crab Helice tridens related to evasion of cannibalism . Yasushi Kurihara, Katsuhiro Sekimoto . Masahide Miyata . amp . 49 . 41–50 . 1988 . . 10.3354/meps049041. free . 1988MEPS...49...41K .
5. Book: http://edb.kulib.kyoto-u.ac.jp/exhibit/b04/image/01/b04s0137.html . . Wilhem de Haan . Wilhem de Haan . Philipp Franz von Siebold . Philipp Franz von Siebold . 1835 . Ocypode (Helice) tridens sp. nov. . 57 . 2009-01-31 . 2011-07-25 . https://web.archive.org/web/20110725014805/http://edb.kulib.kyoto-u.ac.jp/exhibit/b04/image/01/b04s0137.html . dead .