The brown box crab (''Lopholithodes foraminatus'') is a

king crab King crabs are a taxon of decapod crustaceans 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, the most common being the red king crab (''Paralithodes camtsch ...

that lives from Prince William Sound,

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S ...

San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...

, at depths of . It reaches a

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the und ...

length of and feeds on

bivalves Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biv ...

and

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commu ...

. 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 In anatomy and osteology, a foramen (;Entry "foramen"
in

. The crab often lies buried in the sediment, and the two foramens in the

cheliped A chela ()also called a claw, nipper, or pinceris a pincer-like organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through New Latin New Latin (also called Neo-Latin or Modern Latin) is the revival ...

s allow water into the gill chamber for respiration. The

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they ar ...

chamber is also sometimes used by the

commensal Commensalism is a long-term biological interaction ( symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fr ...

fish ''

Careproctus ''Careproctus'' is a genus of snailfishes found in benthic and benthopelagic habitats in the Atlantic, Pacific, Arctic and Southern Oceans. Whether they truly are absent from the Indian Ocean (except for a couple of species in Subantarctic ...

'' to hold its eggs. Brown box crab specimen

References

External links

* King crabs Crustaceans of the eastern Pacific Ocean Crustaceans described in 1859 Taxa named by William Stimpson {{Crab-stub