King crab

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King crabs
Temporal range: Miocene–Recent
Paralithodes californiensis
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Malacostraca
Order: Decapoda
Suborder: Pleocyemata
(unranked): Reptantia
Infraorder: Anomura
Superfamily: Lithodoidea
Samouelle, 1819
Family: Lithodidae
Samouelle, 1819
King crabs often feature prominent spines.

King crabs are a taxon of decapod crustaceans that are 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 with the most common being the red king crab (Paralithodes camtschaticus).

King crabs are not true crabs, and are generally thought to be derived from hermit crab ancestors within the Paguridae, which may explain the asymmetry still found in the adult forms.[2] This ancestry is supported by several anatomical peculiarities which are present only in king crabs and hermit crabs.[3] Although some doubt still exists about this hypothesis, king crabs are the most widely quoted example of carcinisation among the Decapoda.[3] 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[edit]

Although formerly classified among the hermit crabs in the superfamily Paguroidea, king crabs are now placed in a separate superfamily, Lithodoidea.[1] 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; therefore, a separate superfamily in the classification poorly reflects the phylogenetic relationship of this taxon.[3][4]


As of September 2023, 125 species of king crab are known in 10 genera.[5] These include:


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.


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.[7][8][9] Habitat is the main factor separating the range of blue and red king crabs in the Bering Sea.[10] Red king crabs prefer shallow, muddy or sandy habitats in Bristol Bay and Norton Sound,[10][11] while blue king crabs prefer the deeper areas made up of cobble, gravel and rock that occur around the Pribilof, St. Matthew,[12][13] 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.[9] 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.

Red king crabs make up over 90% of the annual king crab harvest. This crab is in the collection of the Children's Museum of Indianapolis.

Paralithodes camtschaticus[edit]

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.[14][15] By 2022 they had spread to the North Sea, becoming both a lucrative new stock to British fisheries, and an invasive species.[16]

Paralithodes platypus[edit]

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.[13] Blue king crabs from the Pribilof Islands are the largest of all the king crabs, sometimes exceeding 18 lb (8 kg) in weight.[17]


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.[18]


Some species of king crab, including those of the genera Lithodes, Neolithodes, Paralithodes, and likely Echidnocerus, act as hosts to some parasitic species of careproctus fish.[19] 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.[citation needed]

See also[edit]


  1. ^ a b De Grave, Sammy; Pentcheff, N. Dean; Ahyong, Shane T.; et al. (2009). "A classification of living and fossil genera of decapod crustaceans" (PDF). The Raffles Bulletin of Zoology. Suppl. 21: 1–109. Archived from the original (PDF) on 2011-06-06.
  2. ^ Noever, Christoph; Glenner, Henrik (2017-07-05). "The origin of king crabs: hermit crab ancestry under the magnifying glass" (PDF). Zoological Journal of the Linnean Society. 182 (2): 300–318. doi:10.1093/zoolinnean/zlx033. Archived (PDF) from the original on 2019-07-16 – via the University of Copenhagen.
  3. ^ a b c Keiler, Jonas; Richter, Stefan; Wirkner, Christian S. (2013-03-19). "Evolutionary morphology of the hemolymph vascular system in hermit and king crabs (Crustacea: Decapoda: Anomala)". Journal of Morphology. 274 (7): 759–778. doi:10.1002/jmor.20133. PMID 23508935. S2CID 24458262.
  4. ^ Anker, Arthur; Paulay, Gustav (2013-10-22). "A remarkable new crab-like hermit crab (Decapoda: Paguridae) from French Polynesia, with comments on carcinization in the Anomura" (PDF). Zootaxa. 3722 (2): 283–300. doi:10.11646/zootaxa.3722.2.9. Archived (PDF) from the original on 2019-07-24.
  5. ^ McLaughlin, Patsy A.; Komai, Tomoyuki; Lemaitre, Rafael; Rahayu, Dwi Listyo (2010-10-31). Low, Martyn E. Y.; Tan, S. H. (eds.). "Annotated checklist of anomuran decapod crustaceans of the world (exclusive of the Kiwaoidea and families Chirostylidae and Galatheidae of the Galatheoidea) Part I – Lithodoidea, Lomisoidea and Paguroidea" (PDF). Zootaxa. Suppl. 23: 5–107. Archived (PDF) from the original on 2016-04-17 – via the Natural History Museum of Los Angeles County.
  6. ^ de Grave, Sammy; Ahyong, Shane T. (2022). "Echidnocerus White, 1842, an overlooked senior synonym of Lopholithodes Brandt, 1848 (Decapoda, Lithodidae)". Crustaceana. 95 (7): 861–865. doi:10.1163/15685403-bja10223. S2CID 252517428.
  7. ^ Jensen, Gregory C.; Armstrong, David A. (1989). "Biennial reproductive cycle of blue king crab, Paralithodes platypus, at the Pribilof Island, Alaska and comparison to a congener, P. camtschatica". Canadian Journal of Fisheries and Aquatic Sciences. 46 (6): 932–940. doi:10.1139/f89-120. ISSN 0706-652X – via ResearchGate.
  8. ^ Klitin, A.K.; Nizyaev, S.A. (1999). "The distribution and life strategies of some commercially important Far Eastern lithodid crabs in the Kuril Islands". Biologiya Morya. Vladivostok. 25 (3): 221–228. ISSN 1063-0740.
  9. ^ a b Stevens, Bradley G. (October 2006). "Timing and duration of larval hatching for blue king crab Paralithodes platypus Brandt, 1850 held in the laboratory". Journal of Crustacean Biology. 26 (4): 495–502. doi:10.1651/S-2677.1. JSTOR 4094179.
  10. ^ a b Essential fish habitat assessment report for the Bering Sea and Aleutian Islands King and Tanner Crabs (PDF) (Report). NOAA Fisheries Report. Vol. II. North Pacific Fishery Research Council. April 2005. Appendix F.3. Archived from the original (PDF) on 2010-05-28. Retrieved 2009-12-06.
  11. ^ Soong, Joyce; Kohler, Tom (October 2005). Norton Sound winter Red King Crab studies (PDF) (Report). Fisheries Data Series. Alaska Department of Fish and Game. No. 05-48. Archived (PDF) from the original on 2017-01-26.
  12. ^ Zheng, Jie; Murphy, M.C.; Kruse, Gordon H. (Summer 1997). Application of a catch-survey analysis to blue king crab stocks near Pribilof and St. Matthew Islands (PDF) (Report). Alaska Fishery Research Bulletin. Vol. 4. pp. 62–74. ISSN 1091-7306. Archived from the original (PDF) on 2009-06-26.
  13. ^ a b Vining, Ivan; Blau, S. Forrest; Pengilly, Doug (October 27–30, 1999). "Evaluating changes in spatial distribution of Blue King Crab near St. Matthew Island". In Kruse, Gordon H.; Bez, Nicolas; Booth, Anthony; Dorn, Martin W.; Hills, Sue; Lipcius, Romuald N.; et al. (eds.). Spatial Processes and Management of Marine Populations. Symposium on Spatial Processes and Management of Marine Populations. University of Alaska Sea Grant College Program (published 2001). pp. 327–348. ISBN 978-1-56612-068-5. Report No. AK-SG-01-02. Archived (PDF) from the original on 2019-01-10.
  14. ^ Bevanger, Lars (2006-08-09). "Norway fears giant crab invasion". BBC News. Archived from the original on 2019-02-16.
  15. ^ Kirby, Alex (2003-09-29). "King crabs march towards the Pole". BBC News. Archived from the original on 2019-03-21.
  16. ^ Horton, Helena (28 January 2022). "King crabs invade UK waters threatening native species". The Guardian.
  17. ^ "King Crab 101 – Lessons from a crab fisherman". Fisherman's Express. Alaska Seafoods. 2000. Archived from the original on 2007-06-20.
  18. ^ Barry, James P.; Taylor, Josi R.; Kuhnz, Linda A.; DeVogelaere, Andrew P. (2016-10-15). "Symbiosis between the holothurian Scotoplanes sp. A and the lithodid crab Neolithodes diomedeae on a featureless bathyal sediment plain". Marine Ecology. 38 (2): e12396. doi:10.1111/maec.12396. eISSN 1439-0485.
  19. ^ Gardner, Jennifer; Orr, James; Stevenson, Duane; Spies, Ingrid; Somerton, David (August 15, 2016). "Reproductive Parasitism between Distant Phyla: Molecular Identification of Snailfish (Liparidae) Egg Masses in the Gill Cavities of King Crabs (Lithodidae)". Copeia. 104 (3): 645–657. doi:10.1643/CI-15-374. S2CID 89241686. Retrieved October 19, 2021.

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