King crab

King crabs are decapod crustaceans of the family Lithodidae[b] 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, making them a prominent 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. The phylogeny of king crabs as hermit crabs who underwent secondary calcification and left their shell has been suspected since the late 1800s. 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.

Source: Wikipedia