King crab explained

King crabs are decapod crustaceans in the family Lithodidae that are chiefly found in cold seas.[1] 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.

Taxonomic controversy

In 2007, the king crabs were moved from their classification among the hermit crabs in the superfamily Paguroidea into a separate superfamily, Lithodoidea. This was 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 reflected the phylogenetic relationship of this taxon.[3] [4] In 2023, king crabs were folded back into Paguroidea, with Lithodoidea being considered superseded.

Species

, 137 species of king crab (one extinct) are known in 15 genera.[5] [6] These are split across its two subfamilies – Hapalogastrinae and Lithodinae – and include:

Hapalogastrinae

Lithodinae

Glyptolithodes

See main article: 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.[8] [9] [10] 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,[11] [12] while blue king crabs prefer the deeper areas made up of cobble, gravel and rock that occur around the Pribilof, St. Matthew,[13] [14] 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.[10] 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

See main article: Red king crab. 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.[15] [16] By 2022 they had spread to the North Sea, becoming both a lucrative new stock to British fisheries, and an invasive species.[17]

Paralithodes platypus

See main article: 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.[14] Blue king crabs from the Pribilof Islands are the largest of all the king crabs, sometimes exceeding 18 lb (8 kg) in weight.[18]

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.[19]

Parasites

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.[20] 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

Notes and References

  1. Book: Poore, Gary C. B. . Marine Decapod Crustacea: A Guide to Families and Genera of the World . Ahyong . Shane T. . Shane T. Ahyong . CRC Press . 2023 . 978-1-4863-1178-1.
  2. Noever. Christoph. Glenner. Henrik. 2017-07-05. The origin of king crabs: hermit crab ancestry under the magnifying glass. live. Zoological Journal of the Linnean Society. 182. 2. 300–318. 10.1093/zoolinnean/zlx033. https://web.archive.org/web/20190716022005/http://macroecointern.dk/pdf-reprints/Noever_ZJLS_2018.pdf. 2019-07-16. the University of Copenhagen.
  3. 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. 10.1002/jmor.20133. 23508935. 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 . live . . 3722 . 2 . 283–300 . 10.11646/zootaxa.3722.2.9 . https://web.archive.org/web/20190724212126/https://www.mapress.com/zootaxa/2013/f/zt03722p300.pdf . 2019-07-24.
  5. 106737. Lithodidae Samouelle, 1819.
  6. McLaughlin. Patsy A.. Komai. Tomoyuki. Lemaitre. Rafael. Rahayu. Dwi Listyo. 2010-10-31. Low. Martyn E. Y.. Tan. S. H.. 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. live. The Raffles Bulletin of Zoology. Suppl. 23. 5–107. https://web.archive.org/web/20160417015104/https://decapoda.nhm.org/pdfs/31605/31605.pdf. 2016-04-17. the Natural History Museum of Los Angeles County.
  7. de Grave. Sammy. Ahyong. Shane T.. Shane T. Ahyong. Echidnocerus White, 1842, an overlooked senior synonym of Lopholithodes Brandt, 1848 (Decapoda, Lithodidae). Crustaceana. 2022 . 95. 7. 861–865. 10.1163/15685403-bja10223. 252517428 .
  8. 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. 10.1139/f89-120. 0706-652X. ResearchGate.
  9. Klitin . A.K. . Nizyaev . S.A. . 1999 . The distribution and life strategies of some commercially important Far Eastern lithodid crabs in the Kuril Islands . . Vladivostok . 25 . 3 . 221–228 . 1063-0740.
  10. Stevens . Bradley G. . October 2006 . Timing and duration of larval hatching for blue king crab Paralithodes platypus Brandt, 1850 held in the laboratory . . 26 . 4 . 495–502 . 10.1651/S-2677.1 . 4094179 . free.
  11. North Pacific Fishery Research Council . April 2005 . Essential fish habitat assessment report for the Bering Sea and Aleutian Islands King and Tanner Crabs . NOAA Fisheries Report . II . Appendix F.3 . 2009-12-06 . dead . https://web.archive.org/web/20100528050924/http://www.fakr.noaa.gov/habitat/seis/final/Volume_II/Appendix_F.3.pdf . 2010-05-28.
  12. Norton Sound winter Red King Crab studies . Soong . Joyce . Kohler . Tom . October 2005 . Fisheries Data Series . No. 05-48 . Alaska Department of Fish and Game . live . https://web.archive.org/web/20170126173119/https://www.adfg.alaska.gov/fedaidpdfs/fds05-48.pdf . 2017-01-26.
  13. 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 . Alaska Fishery Research Bulletin . 4 . 1 . 62–74 . 1091-7306 . dead . https://web.archive.org/web/20090626204855/http://www.adfg.state.ak.us/pubs/afrb/vol4_n1/zhenv4n1.pdf. 2009-06-26.
  14. Vining . Ivan . Blau . S. Forrest . Pengilly . Doug . October 27–30, 1999 . Evaluating changes in spatial distribution of Blue King Crab near St. Matthew Island . Kruse . Gordon H.. Bez . Nicolas . Booth . Anthony . Dorn . Martin W. . Hills . Sue . Lipcius . Romuald N. . Pelletier . Dominique . Roy . Claude . Smith . Stephen J. . 6 . David . Witherell . Spatial Processes and Management of Marine Populations . Symposium on Spatial Processes and Management of Marine Populations . University of Alaska Sea Grant College Program . 2001 . 327–348 . 978-1-56612-068-5 . Report No. AK-SG-01-02 . https://archive.org/stream/spatialprocesses0000symp#page/327/mode/2up . live . registration . https://web.archive.org/web/20190110014209/http://nsgl.gso.uri.edu/aku/akuw99004/akuw99004_full.pdf . 2019-01-10.
  15. News: Bevanger . Lars . 2006-08-09 . Norway fears giant crab invasion . . live . https://web.archive.org/web/20190216075600/http://news.bbc.co.uk/2/hi/europe/4775155.stm . 2019-02-16.
  16. News: Kirby . Alex . 2003-09-29 . King crabs march towards the Pole . . live . https://web.archive.org/web/20190321014138/http://news.bbc.co.uk/2/hi/science/nature/3149782.stm . 2019-03-21.
  17. News: King crabs invade UK waters threatening native species . Horton . Helena . The Guardian . 28 January 2022 .
  18. Web site: King Crab 101 – Lessons from a crab fisherman . 2000 . Fisherman's Express . Alaska Seafoods . dead . https://web.archive.org/web/20070620192239/http://www.fishermansexpress.com/king-crab-101.html . 2007-06-20.
  19. 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 . 10.1111/maec.12396 . 1439-0485.
  20. Gardner . Jennifer . Orr . James . Stevenson . Duane . Spies . Ingrid . Somerton . David . Reproductive Parasitism between Distant Phyla: Molecular Identification of Snailfish (Liparidae) Egg Masses in the Gill Cavities of King Crabs (Lithodidae) . Copeia. August 15, 2016 . 104 . 3 . 645–657 . October 19, 2021 . 10.1643/CI-15-374. 89241686 .

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