King crab

King crabs Temporal range: Early Miocene–Recent PreꞒ Ꞓ O S D C P T J K Pg N
Paralithodes californiensis
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Malacostraca
Order:	Decapoda
Suborder:	Pleocyemata
(unranked):	Reptantia
Infraorder:	Anomura
Superfamily:	Paguroidea Samouelle, 1819
Family:	Lithodidae Samouelle, 1819
Genera[1]
Hapalogastrinae Brandt, 1850 Acantholithodes Holmes, 1895 Dermaturus Brandt, 1850 Hapalogaster Brandt, 1850 Oedignathus Benedict, 1895 Placetron Schalfeew, 1892 Lithodinae Samouelle, 1819 Cryptolithodes Brandt, 1848 Echidnocerus White, 1842[a] Glyptolithodes Faxon, 1895 Lithodes Latreille, 1806 Neolithodes A. Milne-Edwards & Bouvier, 1894 Paralithodes Brandt, 1848 Paralomis White, 1856 Phyllolithodes Brandt, 1848 Rhinolithodes Brandt, 1848 Sculptolithodes Makarov, 1934

King crabs are decapod crustaceans of the family Lithodidae^[b] that are chiefly found in deep waters and are adapted to cold environments.^[2][3] They are composed of two subfamilies: Lithodinae, which tend to inhabit deep waters, are globally distributed, and comprise the majority of the family's species diversity;^[3][4] and Hapalogastrinae, which are endemic to the North Pacific and inhabit exclusively shallow waters.^[3] King crabs superficially resemble true crabs but are generally understood to be closest to the pagurid hermit crabs.^[2][4][5] This placement of king crabs among the hermit crabs is supported by several anatomical peculiarities which are present only in king crabs and hermit crabs, making them a prominent example of carcinisation among decapods.^[6] Several species of king crabs, especially in Alaskan and southern South American waters, are targeted by commercial fisheries and have been subject to overfishing.^[2][7][8]

Taxonomy

The phylogeny of king crabs as hermit crabs who underwent secondary calcification and left their shell has been suspected since the late 1800s.^[4] They are believed to have originated during the Early Miocene in shallow North Pacific waters, where most king crab genera – including all Hapalogastrinae – are distributed and where they exhibit a high amount of morphological diversity.^[4][9]

In 2007, the king crabs were moved from their classification among the hermit crabs in the superfamily Paguroidea into a separate superfamily, Lithodoidea.^[1] 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.^[6][10] In 2023, king crabs were folded back into Paguroidea, with Lithodoidea being considered superseded.^[2] The king crab's relationship to other hermit crabs as well as the family's internal phylogeny can be seen in the following two cladograms:^[4][11]

	Brachyura ("true" crabs)
Anomura	Porcellanidae (porcelain crabs) Munididae (squat lobsters) Parapaguridae (deep water sea anemone hermit crabs) Eumunididae (squat lobster-like) Hippidae (mole crabs or sand crabs)  Paguroidea  Lithodidae (king crabs) Paguridae (hermit crabs) Diogenidae (left-handed hermit crabs) Coenobitidae (terrestrial hermit crabs)

Lithodidae cladogram

Lithodidae Paralithodes brevipes Paralomis/Glyptolithodes Glyptolithodes cristatipes Paralomis zealandica Paralomis granulosa Paralomis dofleini Paralomis pacifica Paralomis birsteini Paralomis cristata Paralomis formosa Paralomis multispina Paralomis hirtella Paralomis spinosissima Paralomis erinacea Paralomis africana Paralomis cristulata Paralomis anamerae Paralomis aculeata Paralomis elongata Echidnocerus Echidnocerus cibarius Echidnocerus foraminatus Neolithodes Neolithodes diomedeae Neolithodes brodiei Neolithodes grimaldii Neolithodes duhameli Neolithodes asperrimus Lithodes Lithodes nintokuae Lithodes turkayi Lithodes longispina Lithodes murrayi Lithodes aequispinus Lithodes couesi Lithodes turritus Lithodes paulayi Lithodes ferox Lithodes maja Lithodes santolla Lithodes confundens Paralithodes platypus Paralithodes camtschaticus Phyllolithodes/Rhinolithodes Phyllolithodes papillosus Rhinolithodes wosnessenskii Acantholithodes hispidus Placetron wosnessenskii Cryptolithodes Cryptolithodes sitchensis Cryptolithodes typicus Hapalogaster Hapalogaster mertensii Hapalogaster grebnitzkii Hapalogaster dentata Oedignathus inermis

As of December 2023^[update], there are 15 known genera of king crabs across two subfamilies.^[12][2][13] These include:^[12]

Hapalogastrinae

• Acantholithodes Holmes, 1895
• Dermaturus Brandt, 1850
• Hapalogaster Brandt, 1850
• Oedignathus Benedict, 1895
• Placetron Schalfeew, 1892

Lithodinae

• Cryptolithodes Brandt, 1848
• Echidnocerus White, 1842^[a]
• Glyptolithodes Faxon, 1895
• Lithodes Latreille, 1806
• Neolithodes A. Milne-Edwards & Bouvier, 1894
• Paralithodes Brandt, 1848
• Paralomis White, 1856
• Phyllolithodes Brandt, 1848
• Rhinolithodes Brandt, 1848
• Sculptolithodes Makarov, 1934

Appearance

King crabs often feature prominent spines, which shrink as they mature.^[5]

King crabs are distinctive among hermit crabs for their highly crab-like appearance.^[5] They are a morphologically diverse group,^[4] but they all have in common the functionalities of their five pairs of legs, called pereopods:^[c] the first and anteriormost set are chelipeds whose right side is generally noticeably more robust than the left; the second, third, and fourth are walking legs tipped with sharp dactyli; and the fifth, used for cleaning, are very small and generally sit inside the branchial chamber.^[5] On their underside, they have a short abdomen – composed of calcified plates – which is asymmetrical in females.^[5] This abdomen (sometimes called a pleon)^[4] is folded against the underside of the cephalothorax and is composed of six segments – called somites or pleonites – and a telson.^[5][2][d] In Hapalogastrinae, this abdomen is soft, while it is hard and calcified in members of Lithodinae.^[4] Lithodids lack any sort of uropod seen in some decapods.^[5]

Distribution

King crabs are typically found in deep waters, especially in polar and subpolar regions and near hydrothermal vents and cold seeps.^[2] Members of Lithodinae can be found in all five of the world's oceans, namely the Pacific, Atlantic, Indian, Southern, and Arctic,^[2][15][16] while members of Hapalogastrinae are only found in the North Pacific.^[3] Members of Hapalogastrinae exhibit a tolerance for higher temperatures than Lithodinae; whereas Lithodinae tend to live exclusively in deep waters or – less commonly – high-latitude shallow waters, Hapalogastrinae are found only in shallow waters (<100 m (330 ft)).^[3]

Fisheries

Red king crabs are widely fished in Alaska.

Because of their large size, the taste of their meat, and their status as a delicacy, some species of king crabs are caught and sold as food.^[17][8][7] Red (Paralithodes camtschaticus) and blue (Paralithodes platypus) king crabs are heavily targeted by commercial fisheries in Alaska and have been for several decades. However, populations have fluctuated in the past 25 years, and some areas are currently closed due to overfishing.^{[18][19][20][21]} Alaskan fisheries additionally target the golden king crab (Lithodes aequispinus).^[22] In South America, both the southern king crab (Lithodes santolla) and several species of Paralomis are targeted by commercial fisheries,^[17][2] and as a result, the population of L. santolla has seen a dramatic decline.^[8]

Symbionts and parasites

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.^[23] Endosymbiotic microorganisms of the order Eccrinida have been found in Paralithodes camtschaticus and Lithodes maja, living in their hindgut between molts.^[24]

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.^[25] 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.^[25] On occasion king crabs have been found to be host to the eggs of multiple species of careproctus simultaneously.^[25] King crabs are additionally parasitized by rhizocephalan genus Briarosaccus, a type of barnacle.^[26] The barnacle irreversibly sterilizes the crab, and over 50% of some king crab populations are affected.^[26]

See also

• Crustaceans portal
• Alaskan king crab fishing
• Majoidea

Notes

1. Known as Lopholithodes Brandt, 1848 until 2022 after the senior synonym Echidnocerus was rediscovered.^[14]
2. Often collectively referred to as "lithodids".^[2]
3. These legs are commonly labeled pereopod 1–5 starting from the anterior.^[5]
4. These segments are commonly labeled somite/pleonite 1–6 starting from the posterior.^[5][2]

References

1. 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. Poore, Gary C. B.; Ahyong, Shane T. (2023). "Anomura". Marine Decapod Crustacea: A Guide to Families and Genera of the World. CRC Press. pp. 311–317. ISBN 978-1-4863-1178-1.
3. Hall, Sally; Thatje, Sven (October 2009). "Global bottlenecks in the distribution of marine Crustacea: temperature constraints in the family Lithodidae" (PDF). Journal of Biogeography. 36 (11): 2125–2135. Bibcode:2009JBiog..36.2125H. doi:10.1111/j.1365-2699.2009.02153.x. Archived (PDF) from the original on 29 May 2023.
4. 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.
5. Ahyong, Shane T. (2010). The Marine Fauna of New Zealand: King Crabs of New Zealand, Australia, and the Ross Sea (Crustacea: Decapoda: Lithodidae) (PDF). NIWA Biodiversity Memoirs. Vol. 123. National Institute of Water and Atmospheric Research. pp. 5–15. ISBN 978-0478232851. LCCN 2010497356. Archived (PDF) from the original on 15 February 2020.
6. 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.
7. Dvoretsky, Alexander G.; Dvoretsky, Vladimir G. (November 2017). "Red king crab (Paralithodes camtschaticus) fisheries in Russian waters: historical review and present status". Reviews in Fish Biology and Fisheries. 28 (2): 331–353. doi:10.1007/s11160-017-9510-1. ISSN 0960-3166.
8. Anger, Klaus; Lovrich, Gustavo A.; Thatje, Sven; Calcagno, Javier A. (August 2004). "Larval and early juvenile development of Lithodes santolla (Molina, 1782) (Decapoda: Anomura: Lithodidae) reared at different temperatures in the laboratory". Journal of Experimental Marine Biology and Ecology. 306 (2): 217–230. Bibcode:2004JEMBE.306..217A. doi:10.1016/j.jembe.2004.01.010 – via ResearchGate.
9. Karasawa, Hiroaki; Mizuno, Yoshiaki; Hachiya, Kiichiro; Ando, Yusuke (March 2017). "Reappraisal of anomuran and brachyuran decapods from the lower Miocene Morozaki Group, Japan, collected by the Tokai Fossil Society" (PDF). Bulletin of the Mizunami Fossil Museum (43): 47–69. ISSN 0385-0900. Retrieved 5 December 2024 – via the Mizunami Fossil Museum.
10. 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.
11. Wolfe, Joanna M.; Breinholt, Jesse W.; Crandall, Keith A.; Lemmon, Alan R.; Lemmon, Emily Moriarty; Timm, Laura E.; et al. (24 April 2019). "A phylogenomic framework, evolutionary timeline and genomic resources for comparative studies of decapod crustaceans". Proceedings of the Royal Society B. 286 (1901). doi:10.1098/rspb.2019.0079. PMC 6501934. PMID 31014217.
12. Ahyong, Shane T. (2023). "Lithodidae Samouelle, 1819". WoRMS. World Register of Marine Species. Retrieved 4 October 2024.
13. 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). The Raffles Bulletin of Zoology. Suppl. 23: 5–107. Archived (PDF) from the original on 2016-04-17 – via the Natural History Museum of Los Angeles County.
14. 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.
15. Hall, Sally; Thatje, Sven (February 2018). "Evolution through cold and deep waters: the molecular phylogeny of the Lithodidae (Crustacea: Decapoda)". The Science of Nature. 105: 19. doi:10.1007/s00114-018-1544-2. PMC 5829116. PMID 29488024.
16. Dvoretsky, Alexander G.; Dvoretsky, Vladimir G. (September 2013). "Population dynamics of the invasive lithodid crab, Paralithodes camtschaticus, in a typical bay of the Barents Sea". ICES Journal of Marine Science. 70 (6): 1255–1262. doi:10.1093/icesjms/fst037.
17. Cocito, Laura L.; Permigiani, Sabrina; Tapella, Federico; Tomac, Alejandra; Czerner, Marina; Romero, M. Carolina (30 August 2024). "Shelf-life of cooked meat of southern king crab (Lithodes santolla) and false king crab (Paralomis granulosa) during refrigerated storage". Heliyon. 10 (16): e36475. doi:10.1016/j.heliyon.2024.e36475. PMC 11388567. PMID 39262967.
18. 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.
19. 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. 25 (3). Vladivostok: 221–228. ISSN 1063-0740.
20. 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.
21. 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.
22. Olson, A.P.; Siddon, C.E.; Eckert, G.L. (March 2018). "Spatial variability in size at maturity of golden king crab (Lithodes aequispinus) and implications for fisheries management". Royal Society Open Science. 5 (3): 171802. Bibcode:2018RSOS....571802O. doi:10.1098/rsos.171802. PMC 5882709. PMID 29657785.
23. 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.
24. Pavlova, L.V. (2018). "First Finding of Representatives of the Eccrinida Order in the Digestive Tract of King Crab Specie from the Barents Sea". Doklady Biological Sciences. 483 (1): 231–234. doi:10.1134/S0012496618060066. ISSN 0012-4966. PMID 30603945.
25. 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.
26. Noever, Christoph (27 January 2017). Coevolution between king crabs (Paguridae: Lithodinae) and parasitic barnacles (Cirripedia: Rhizocephala) (Doctoral thesis). University of Bergen. Retrieved 15 October 2024.

Further reading

• Stevens, Bradley G., ed. (2014). King Crabs of the World: Biology and Fisheries Management (1st ed.). CRC Press. doi:10.1201/b16664. ISBN 978-1-4398-5542-3.

External links

• Media related to Lithodidae at Wikimedia Commons
• Data related to Lithodidae at Wikispecies
• The dictionary definition of king crab at Wiktionary