King Crab

King crabs are a taxon of decapod crustaceans chiefly found in cold seas. Because of their large size and the taste of their meat, many species are widely caught and sold as food, the most common being the red king crab (''Paralithodes camtschaticus'').

King crabs are generally thought to be derived from hermit crab-like ancestors within the Paguridae, which may explain the asymmetry still found in the adult forms. This ancestry is supported by several anatomical peculiarities which are present only in king crabs and hermit crabs. Although some doubt still exists about this hypothesis, king crabs are the most widely quoted example of carcinisation among the Decapoda. The evidence for this explanation comes from the asymmetry of the king crab's abdomen, which is thought to reflect the asymmetry of hermit crabs, which must fit into a spiral shell.

Controversial taxon

Although formerly classified among the hermit crabs in the superfamily Paguroidea, king crabs are now placed in a separate superfamily, Lithodoidea.
This is not without controversy, as there is widespread consensus in the scientific community that king crabs are derived from hermit crabs and closely related to pagurid hermit crabs, and therefore a separate superfamily in the classification poorly reflects the phylogenetic relationship of this taxon.

Species

Around 121 species are known, in 10 genera:

* ''Cryptolithodes'' Brandt, 1848
** ''Cryptolithodes expansus'' Miers, 1879
** ''Cryptolithodes sitchensis'' Brandt, 1853 – umbrella crab
** ''Cryptolithodes typicus'' Brandt, 1848 – butterfly crab
* '' Glyptolithodes'' Faxon, 1895
** ''Glyptolithodes cristatipes'' (Faxon, 1893)
* ''Lithodes'' Latreille, 1806
** ''Lithodes aequispinus'' J. E. Benedict, 1895 – golden king crab or brown king crab
** '' Lithodes aotearoa'' Ahyong, 2010
** '' Lithodes australiensis'' Ahyong, 2010
** '' Lithodes ceramensis'' Takeda & Nagai, 2004
** ''Lithodes chaddertoni'' Ahyong, 2010
** '' Lithodes confundens'' Macpherson, 1988
** ''Lithodes couesi'' J. E. Benedict, 1895 – scarlet king crab
** ''Lithodes ferox'' Filhol, 1885
** ''Lithodes formosae'' Ahyong & Chan, 2010
** ''Lithodes galapagensis'' Hall & Thatje, 2009
** ''Lithodes jessica'' Ahyong, 2010
** ''Lithodes longispina'' Sakai, 1971
** ''Lithodes macquariae'' Ahyong, 2010
** ''Lithodes maja'' (Linnaeus, 1758) – Norway king crab or trollkrabbe
** ''Lithodes mamillifer'' Macpherson, 1988d
** '' Lithodes mandtii''
** ''Lithodes manningi'' Macpherson, 1988
** ''Lithodes megacantha'' Macpherson, 1991
** ''Lithodes murrayi'' Henderson, 1888
** ''Lithodes nintokuae'' Sakai, 1976
** ''Lithodes panamensis'' Faxon, 1893
** ''Lithodes paulayi'' Macpherson & Chan, 2008
** ''Lithodes rachelae'' Ahyong, 2010
** ''Lithodes richeri'' Macpherson, 1990
** '' Lithodes robertsoni'' Ahyong, 2010
** ''Lithodes santolla'' (Molina, 1782) – Chilean centolla or Chilean king crab
** ''Lithodes turkayi'' Macpherson, 1988
** '' Lithodes turritus'' Ortmann, 1892
** ''Lithodes unicornis'' Macpherson, 1984
** ''Lithodes wiracocha'' Haig, 1974
* ''Lopholithodes'' Brandt, 1848
** '' Lopholithodes foraminatus'' (Stimpson, 1859) – brown box crab
** '' Lopholithodes mandtii'' Brandt, 1848 – Puget Sound king crab
* ''Neolithodes'' A. Milne-Edwards & Bouvier, 1894
** ''Neolithodes agassizii'' (S. I. Smith, 1882)
** ''Neolithodes asperrimus'' Barnard, 1947
** '' Neolithodes brodiei'' Dawson & Yaldwyn, 1970
** '' Neolithodes bronwynae'' Ahyong, 2010
** '' Neolithodes capensis'' Stebbing, 1905
** ''Neolithodes diomedeae'' (J. E. Benedict, 1895)
** '' Neolithodes duhameli'' Macpherson, 2004
** '' Neolithodes flindersi'' Ahyong, 2010
** ''Neolithodes grimaldii'' (A. Milne-Edwards & Bouvier, 1894)
** ''Neolithodes indicus'' Padate, Cubelio & Takeda, 2020
** '' Neolithodes nipponensis'' Sakai, 1971
** '' Neolithodes vinogradovi'' Macpherson, 1988
** '' Neolithodes yaldwyni'' Ahyong & Dawson, 2006
* ''Paralithodes'' Brandt, 1848
** '' Paralithodes brevipes'' (H. Milne Edwards & Lucas, 1841)
** ''Paralithodes californiensis'' (J. E. Benedict, 1895) – California king crab
** ''Paralithodes camtschaticus'' ( Tilesius, 1815) – red king crab
** '' Paralithodes platypus'' Brandt, 1850 – blue king crab
** '' Paralithodes rathbuni'' (J. E. Benedict, 1895)
* '' Paralomis'' White, 1856
** '' Paralomis aculeata'' Henderson, 1888
** '' Paralomis africana'' Macpherson, 1982
** '' Paralomis alcockiana'' Hall & Thatje, 2009
** '' Paralomis anamerae'' Macpherson, 1988
** '' Paralomis arae'' Macpherson, 2001
** '' Paralomis arethusa'' Macpherson, 1994
** ''Paralomis aspera'' Faxon, 1893
** ''Paralomis birsteini'' Macpherson, 1988
** '' Paralomis bouvieri'' Hansen, 1908
** '' Paralomis ceres'' Macpherson, 1989
** ''Paralomis chilensis'' Andrade, 1980
** ''Paralomis cristata'' Takeda & Ohta, 1979
** ''Paralomis cristulata'' Macpherson, 1988
** ''Paralomis cubensis'' Chace, 1939
** ''Paralomis danida'' Takeda & Bussarawit, 2007
** ''Paralomis dawsoni'' Macpherson, 2001
** ''Paralomis debodeorum'' Feldmann, 1998 †
** ''Paralomis diomedeae'' (Faxon, 1893)
** ''Paralomis dofleini'' Balss, 1911
** ''Paralomis echidna'' Ahyong, 2010
** '' Paralomis elongata'' Spiridonov, Türkay, Arntz & Thatje, 2006
** '' Paralomis erinacea'' Macpherson, 1988
** '' Paralomis formosa'' Henderson, 1888
** '' Paralomis gowlettholmes'' Ahyong, 2010
** '' Paralomis granulosa'' (Hombron & Jacquinot, 1846)
** ''Paralomis grossmani'' Macpherson, 1988
** '' Paralomis haigae'' Eldredge, 1976
** '' Paralomis hirtella'' de Saint Laurent & Macpherson, 1997
** '' Paralomis histrix'' (De Haan, 1849)
** '' Paralomis hystrixoides'' Sakai, 1980
** '' Paralomis inca'' Haig, 1974
** '' Paralomis indica'' Alcock & Anderson, 1899
** '' Paralomis investigatoris'' Alcock & Anderson, 1899
** '' Paralomis jamsteci'' Takeda & Hashimoto, 1990
** '' Paralomis japonicus'' Balss, 1911
** '' Paralomis kyushupalauensis'' Takeda, 1985
** '' Paralomis longidactylus'' Birstein & Vinogradov, 1972
** '' Paralomis longipes'' Faxon, 1893
** '' Paralomis makarovi'' Hall & Thatje, 2009
** '' Paralomis manningi'' Williams, Smith & Baco, 2000
** '' Paralomis medipacifica'' Takeda, 1974
** '' Paralomis mendagnai'' Macpherson, 2003
** '' Paralomis microps'' Filhol, 1884
** '' Paralomis multispina'' (Benedict, 1895)
** '' Paralomis nivosa'' Hall & Thatje, 2009
** ''Paralomis ochthodes'' Macpherson, 1988
** ''Paralomis odawarai'' (Sakai, 1980)
** '' Paralomis otsuae'' Wilson, 1990
** '' Paralomis pacifica'' Sakai, 1978
** '' Paralomis papillata'' (Benedict, 1895)
** '' Paralomis pectinata'' Macpherson, 1988
** '' Paralomis phrixa'' Macpherson, 1992
** '' Paralomis poorei'' Ahyong, 2010
** '' Paralomis roeleveldae'' Kensley, 1981
** '' Paralomis seagranti'' Eldredge, 1976
** '' Paralomis serrata'' Macpherson, 1988
** '' Paralomis spectabilis'' Hansen, 1908
** '' Paralomis spinosissima'' Birstein & Vinogradov, 1972
** '' Paralomis staplesi'' Ahyong, 2010
** '' Paralomis stella'' Macpherson, 1988
** '' Paralomis stevensi'' Ahyong & Dawson, 2006
** '' Paralomis taylorae'' Ahyong, 2010
** '' Paralomis truncatispinosa'' Takeda & Miyake, 1980
** '' Paralomis tuberipes'' Macpherson, 1988
** '' Paralomis verrilli'' (Benedict, 1895)
** '' Paralomis webberi'' Ahyong, 2010
** '' Paralomis zealandica'' Dawson & Yaldwyn, 1971
* '' Phyllolithodes'' Brandt, 1848
** ''Phyllolithodes papillosus'' Brandt, 1848 – flatspine triangle crab, heart crab
* '' Rhinolithodes'' Brandt, 1848
** ''Rhinolithodes wosnessenskii'' Brandt, 1848 – rhinoceros crab
* '' Sculptolithodes'' Makarov, 1934
** ''Sculptolithodes derjugini'' Makarov, 1934

''Glyptolithodes''

''Glyptolithodes'' is found chiefly in the Southern Hemisphere, but extending as far north as California, although all its closest relatives live in the Northern Hemisphere. Its single species, ''G. cristatipes'', was originally placed in the genus '' Rhinolithodes''.

''Paralithodes''

Red (''P. camtschaticus'') and blue (''P. platypus'') king crabs are some of the most important fisheries in Alaska. However, populations have fluctuated in the past 25 years, and some areas are currently closed due to overfishing. The two species are similar in size, shape and life history. Habitat is the main factor separating the range of blue and red king crabs in the Bering Sea. Red king crabs prefer shallow, muddy or sandy habitats in Bristol Bay and Norton Sound, while blue king crabs prefer the deeper areas made up of cobble, gravel and rock that occur around the Pribilof, St. Matthew, St. Lawrence, and Diomede Islands.

Red king crabs have an 11-month brood cycle in their first reproductive year and a 12-month cycle thereafter. Both red and blue king crabs have planktotrophic larvae that undergo 4 zoeal stages in the water column and a non-feeding intermediate glaucothoe stage which seeks appropriate habitat on the sea floor.

''Paralithodes camtschaticus''

The red king crab, ''Paralithodes camtschaticus'', is a very large species, sometimes reaching a carapace width of 11 in (28 cm) and a leg span of 6 ft (1.8 m). Its natural range is the Bering Sea around the Kamchatka Peninsula area, between the Aleutian Islands and St. Lawrence Island. It can also be found in the Barents Sea and the European Arctic, where it was intentionally introduced and has now become a pest. By 2022 they had spread to the North Sea, becoming both a lucrative new stock to British fisheries, and an invasive species.

''Paralithodes platypus''

The blue king crab, ''Paralithodes platypus'', lives near St. Matthew Island, the Pribilof Islands, and the Diomede Islands, Alaska, and there are populations along the coasts of Japan and Russia. Blue king crabs from the Pribilof Islands are the largest of all the king crabs, sometimes exceeding 18  lb (8  kg) in weight.

Symbiosis

Juveniles of species of king crabs, including ''Neolithodes diomedeae'', use a species (''Scotoplanes Sp. A'') of sea cucumber (often known as “sea pigs”) as hosts and can be found on top of and under ''Scotoplanes''. The ''Scotoplanes'' reduce the risk of predation for the ''N. diomedeae'', while the ''Scotoplanes'' are not harmed from being hosts, which supports the consensus that the two organisms have a commensal relationship.

Parasites

Some species of king crab, including lithodes, neolithodes, paralithodes, and likely lopholithodes, act as hosts to some parasitic species of careproctus fish. The careproctus lays eggs in the gill chamber of the king crab which serves as a well-protected and aerated area for the eggs to reside until they hatch. On occasion king crabs have been found to be host to the eggs of multiple species of careproctus simultaneously.

See also

* Alaskan king crab fishing
* '' Deadliest Catch''

References

External links

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{{Taxonbar, from=Q1861297

Anomura
Edible crustaceans
Alaskan cuisine