[2] Red king crabs can reach a carapace width up to 28 cm (11 in), a leg span of 1.8 m (5.9 ft),[3] and a weight of 12.7 kg (28 lb).

Today, red king crabs infrequently surpass 17 cm (7 in) in carapace width and the average male landed in the Bering Sea weighs 2.9 kg (6.4 lb).

[2] It was introduced artificially by the Soviet Union into the Murmansk Fjord, Barents Sea, during the 1960s to provide a new, and valuable, catch in Europe.

[1] The depth at which it can live has much to do with what stage of its lifecycle it is in; newly hatched crab (zoea larvae) stay in the shallower waters where food and protection are plentiful.

They migrate in the winter or early spring to shallower depths for mating, but most of their lives are spent in the deep waters where they feed.

It is most commonly caught in the Bering Sea and Norton Sound, Alaska, and is particularly difficult to catch, but is nonetheless one of the most preferred crabs for consumption.

[9] In the 1960s, the Soviet Union transported red king crabs from the North Pacific Ocean to the Murmansk Fjord.

A fisherman in Honningsvåg (a town near the North Cape) complained that king crabs' claws were ruining fishing nets and deep lines.

[15] In the Norwegian Sea, some evidence indicates that the red king crabs eat the egg masses of the capelin, which is an important prey for the cod.

[16] In January 2022 it was reported that fishermen in the United Kingdom had caught red king crabs,[17] but they were later identified as the native Lithodes maja.

The mass fraction of carapace from these wastes is approximately 60%; the rest comprises the entrails (including the digestive organ, the hepatopancreas).

The hepatopancreas of the digestive system of commercial crabs is a valuable source of a complex of enzymes with various activities: collagenase, protease, hyaluronidase, lipase, nuclease, etc.

The hyperosmoticity is due to the higher sodium and potassium concentrations in the hemolymph compared to the surrounding water they live in.

They grow slower in acidified water (pH 7.8 instead of 8.0) and eventually die after longer exposure times because of the imbalance of the organisms' acid-base equilibrium.

The carapace is a covering of sheets of exoskeleton that overhang the thorax vertically to fit over the base of the thoracic legs.

[26] The water is drawn in from behind the walking legs then expelled from the branchial chambers through the tubes called prebronchial apertures, which are located beside the mouth.

[28] Due to the environment to which it is exposed, the posterior gills of the crab can also be cleared of parasites and sediment by increasing the movement of its fifth set of primitive legs.

[25]: 653  Heartbeats originate in nervous tissue; innervated muscle cells cause the heart to contract when stimulated by nerve impulses.

The Frank-Starling mechanism refers to the vitally important intrinsic control of the heart; mainly, the stretching of the cardiac muscle tends to increase the force of its contraction by an effect at the cellular level.

Red king crab blood contains leukocytes and the second-most common respiratory pigment called hemocyanin.