King crab

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 generally thought to be derived from hermit crab 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; therefore, a separate superfamily in the classification poorly reflects the phylogenetic relationship of this taxon.
Species
, 125 species of king crab are known in 10 genera. These include:
Cryptolithodes
Cryptolithodes expansus
Cryptolithodes sitchensis – umbrella crab
Cryptolithodes typicus – butterfly crab
Echidnocerus
Echidnocerus cibarius – Puget Sound king crab
Echidnocerus foraminatus – brown box crab
Glyptolithodes
Glyptolithodes cristatipes
Lithodes
Lithodes aequispinus – golden king crab or brown king crab
Lithodes aotearoa
Lithodes australiensis
Lithodes ceramensis
Lithodes chaddertoni
Lithodes confundens
Lithodes couesi – scarlet king crab
Lithodes ferox
Lithodes formosae
Lithodes galapagensis
Lithodes jessica
Lithodes longispina
Lithodes macquariae
Lithodes maja – Norway king crab or trollkrabbe
Lithodes mamillifer d
Lithodes manningi
Lithodes megacantha
Lithodes murrayi
Lithodes nintokuae
Lithodes panamensis
Lithodes paulayi
Lithodes rachelae
Lithodes richeri
Lithodes robertsoni
Lithodes santolla – Chilean centolla or Chilean king crab
Lithodes turkayi
Lithodes turritus
Lithodes unicornis
Lithodes wiracocha
Neolithodes
Neolithodes agassizii
Neolithodes asperrimus
Neolithodes brodiei
Neolithodes bronwynae
Neolithodes capensis
Neolithodes diomedeae
Neolithodes duhameli
Neolithodes flindersi
Neolithodes grimaldii
Neolithodes indicus
Neolithodes nipponensis
Neolithodes vinogradovi
Neolithodes yaldwyni
Paralithodes
Paralithodes brevipes
Paralithodes californiensis – California king crab
Paralithodes camtschaticus – red king crab
Paralithodes platypus – blue king crab
Paralithodes rathbuni
Paralomis
Paralomis aculeata
Paralomis africana
Paralomis alcockiana
Paralomis anamerae
Paralomis arae
Paralomis arethusa
Paralomis aspera
Paralomis birsteini
Paralomis bouvieri
Paralomis ceres
Paralomis chilensis
Paralomis cristata
Paralomis cristulata
Paralomis cubensis
Paralomis danida
Paralomis dawsoni
Paralomis debodeorum †
Paralomis diomedeae
Paralomis dofleini
Paralomis echidna
Paralomis elongata
Paralomis erinacea
Paralomis formosa
Paralomis gowlettholmes
Paralomis granulosa
Paralomis grossmani
Paralomis haigae
Paralomis hirtella
Paralomis histrix
Paralomis hystrixoides
Paralomis inca
Paralomis indica
Paralomis investigatoris
Paralomis jamsteci
Paralomis japonicus
Paralomis kyushupalauensis
Paralomis longidactylus
Paralomis longipes
Paralomis macphersoni
Paralomis makarovi
Paralomis manningi
Paralomis medipacifica
Paralomis mendagnai
Paralomis microps
Paralomis multispina
Paralomis nivosa
Paralomis ochthodes
Paralomis odawarai
Paralomis okitoriensis
Paralomis otsuae
Paralomis pacifica
Paralomis papillata
Paralomis pectinata
Paralomis phrixa
Paralomis poorei
Paralomis roeleveldae
Paralomis seagranti
Paralomis serrata
Paralomis spectabilis
Paralomis spinosissima
Paralomis staplesi
Paralomis stella
Paralomis stevensi
Paralomis taylorae
Paralomis truncatispinosa
Paralomis tuberipes
Paralomis verrilli
Paralomis webberi
Paralomis zealandica
Phyllolithodes
Phyllolithodes papillosus – flatspine triangle crab
Rhinolithodes
Rhinolithodes wosnessenskii – rhinoceros crab
Sculptolithodes
Sculptolithodes derjugini
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 those of the genera Lithodes, Neolithodes, Paralithodes, and likely Echidnocerus, 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
Anomura
Edible crustaceans
Alaskan cuisine