King crabs are decapod crustaceans of the family Lithodidae that are chiefly found in deep waters and are adapted to cold environments. 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; and Hapalogastrinae, which are endemic to the North Pacific and inhabit exclusively shallow waters. King crabs superficially resemble true crabs but are generally understood to be closest to the pagurid hermit crabs. 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. Although some doubt still exists about this hypothesis, king crabs are the most widely quoted example of carcinisation among decapods. Several species of king crabs, especially in Alaskan and southern South American waters, are targeted by commercial fisheries and have been subject to overfishing.
Ocypode is a genus of ghost crabs found in the sandy shores of tropical and subtropical regions throughout the world. They have a box-like body, thick and elongated eyestalks, and one claw is larger than the other in both males and females. They inhabit deep burrows in the intertidal zone. They are primarily nocturnal, and are generalist scavengers and predators of small animals. The genus contains 21 species.
The Ocypodoidea, or ocypoid crabs, are a superfamily of crabs, named after the genus Ocypode. It contains the following families:
Ovalipes is a genus of crabs in the family Ovalipidae.
Cancridae is a family of crabs. It comprises six extant genera, and ten exclusively fossil genera, in two subfamilies:
The brown box crab is a king crab that lives from Prince William Sound, Alaska to San Diego, California, at depths of 0–547 metres (0–1,795 ft). It reaches a carapace length of 150 millimetres (5.9 in) and feeds on bivalves and detritus. The box crab gets its name from a pair of round tunnel-like openings that form between the claws and adjacent legs when the animal folds its limbs up against its body. Both claws, and their adjacent legs, have matching half-circle notches in them that line up to create a circle-shaped opening when the limbs are tightly pulled against one another. This tubular round opening is called a foramen. The crab often lies buried in the sediment, and the two foramens in the chelipeds allow water into the gill chamber for respiration. The gill chamber is also sometimes used by the commensal fish Careproctus to hold its eggs.
The Puget Sound king crab, is a species of king crab which inhabits the oceans of the Pacific coast of North America from Alaska to central California. Adults are orange, red and purple in color, while juveniles are either mostly orange or have small blotches of red and purple. They can be recognized by their blunt bumps on their carapace. Puget Sound king crabs are larger than the similar brown box crab, with an average size of 6–10 inches (15–25 cm).
Paralomis is a genus of king crabs. It includes the following species:
Trapezioidea is a superfamily of crabs. Its members live symbiotically with corals and have a fossil record stretching back to the Eocene.
Lithodes is a genus of king crabs. Today there are about 30 recognized species, but others formerly included in this genus have been moved to Neolithodes and Paralomis. They are found in oceans around the world, ranging from shallow to deep waters, but mostly at depths of 100–1,000 m (300–3,300 ft). They are restricted to relatively cold waters, meaning that they only occur at high depths at low latitudes, but some species also shallower at high latitudes. They are medium to large crabs, and some species are or were targeted by fisheries.
Epiactaea is a genus of crabs in the family Xanthidae, containing the following species:
Paraetisus globulus is a species of crab in the family Xanthidae, the only species in the genus Paraetisus. It was described in 1933 by Charles Melbourne Ward.
Neolithodes is a genus of king crabs, in the family Lithodidae. They are found in all major oceans, both in high and low latitudes. Although there are records from water as shallow as 124 m (407 ft) in cold regions, most records are much deeper, typically 700–2,000 m (2,300–6,600 ft), with the deepest confirmed at 5,238 m (17,185 ft). They are fairly large to large crabs that typically are reddish in color and spiny, although the size of these spines varies depending on species.
Hypothalassia is a genus of temperate and tropical deep sea crabs that are found in both Australian and Japanese waters. It comprises two species: Hypothalassia acerba Koh & Ng, 2000, and Hypothalassia armata, both known as the champagne crab.
Oregonia is a genus of crabs, comprising two extant species and one fossil species: It is classified in the family Oregoniidae under the spider crab superfamily Majoidea.
Hyastenus is a genus of crabs in the family Epialtidae, subfamily Pisinae, containing the following extant species:
Paralomis zealandica, also known as the prickly king crab, is a species of king crab which lives at a depth between 254–1,212 m (833–3,976 ft) in New Zealand. It has a spiky carapace.
Neolithodes diomedeae is a species of king crab which is found in the eastern Pacific Ocean, the southwestern Atlantic Ocean, and the Bellingshausen and Scotia Seas in the Southern Ocean. They occur from 200 to 2,454 m.
Phyllolithodes is a monospecific genus of king crab in the family Lithodidae. Its only species, Phyllolithodes papillosus, lives in the intertidal zone and the subtidal zone. It can be found as far north as Unalaska in the Aleutian Islands and as far south as San Miguel Island in Southern California.
Hapalogaster is a genus of king crabs, containing the following four species:
