Hapalogastrinae Brandt, 1850 Lithodinae Samouelle, 1819 King crabs are decapod crustaceans of the family Lithodidae[b] that are chiefly found in deep waters and are adapted to cold environments.

[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.

[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.

[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] King crabs are typically found in deep waters, especially in polar and subpolar regions and near hydrothermal vents and cold seeps.

[3] 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.

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