Snow crabs have equally long and wide carapaces, or protective shell-coverings, over their bodies.

Their tubercles, or the bodily projections on their shells, are moderately enclosed in calcium deposits, and they boast hooked setae, which are rigid, yet springy, hair-like organs on their claws.

In the Northwest Atlantic, they are found in the areas near Greenland, Newfoundland, in the Gulf of St. Lawrence, and on the Scotian Shelf.

[2] In the North Pacific, this crab is found in areas ranging from Alaska to northern Siberia, and through the Bering Strait to the Aleutian Islands, Japan, and Korea.

[6] Another commercially important species, introduced deliberately to the same region, the red king crab, already has established itself in Barents Sea.

Similarly, snow crabs likely will have an adverse effect on the native species of the Barents Sea.

[6] Snow crabs are found in the ocean's shelf and upper slope, on sandy and muddy bottoms.

[citation needed] Snow crabs mainly reside in very cold waters, between −1 and 5 °C (30 and 41 °F), but can be found at temperatures up to 10 °C (50 °F).

[7] Chionoecetes opilio crabs eat other invertebrates in the benthic shelf, such as crustaceans, bivalves, brittle stars, polychaetes, and even phytobenthos and foraminiferans.

Males typically prove to be better predators than mature females, and prey type depends upon predator size, with the smallest crabs feeding mainly on amphipods and ophiuroids, while the largest crabs feed mainly on annelids, crustacean decapods, and fish.

[7] Off the coast of Newfoundland, two amphipod species – Ischyrocerus commensalis and Gammaropsis inaequistylis – have been found to live on the carapace of the snow crab.

[9] Snow crabs have a very high reproductive potential; each year, every female carries eggs.

[17] The first valid scientific name was provided by Otto Fabricius in 1788, when he redescribed the species as Cancer opilio.