Edible Crab

The carapace of C. pagurus adults is a reddish-brown colour, while in young specimens it is purple-brown. It occasionally bears white patches, and is shaped along the front edge into nine rounded lobes, resembling a pie crust. Males typically have a carapace 60 mm (2+1⁄4 in) long, and females 98 mm (3+3⁄4 in) long, although they may reach up to 150 mm (6 in) long in exceptional cases. Carapace width is typically 150 mm (6 in), or exceptionally up to 250 mm (9+3⁄4 in). A fold of the carapace extends ventrally to constitute a branchial chamber where the gills lie.

The first pereiopod is modified into a strong cheliped (claw-bearing leg); the claw's fingers, the dactylus and propodus, are black at the tips. The other pereiopods are covered with rows of short stiff setae; the dactylus of each is black towards the tip, and ends in a sharp point.

C. pagurus is abundant throughout the northeast Atlantic as far as Norway in the north and North Africa in the south, on mixed coarse grounds, mud, and sand from the shallow sublittoral to depths around 100 m (300 ft; 50 fathoms). It is frequently found inhabiting cracks and holes in rocks, but occasionally also in open areas. Smaller specimens may be found under rocks in the littoral zone. Unconfirmed reports suggest that C. pagurus may also occur in the Mediterranean Sea and Black Sea.

Reproduction occurs in winter; the male stands over the female and forms a cage with his legs protecting her while she moults. Internal fertilisation takes place before the hardening of the new carapace, with the aid of two abdominal appendages (gonopods). After mating, the female retreats to a pit on the sea floor to lay her eggs. Between 250,000 and 3,000,000 fertilised eggs are held under the female's abdomen up to eight months until they hatch.

C. pagurus is heavily exploited commercially throughout its range, being the most commercially important crab species in Western Europe. The crabs are caught using crab pots (similar to lobster pots), also known as creels, which are placed offshore and baited. The catch of C. pagurus has increased steadily, rising from 26,000 tonnes in 1978 to 60,000 t in 2007, of which more than 70% was caught around the British Isles. The fishery is widely dispersed around the British and Irish coasts, and C. pagurus is thought to be overfished across much of this area. Most of the edible crabs caught by the British fleet are exported live for sale in France and Spain.