size and folded under the sternum. Juveniles settle to the sea floor in the intertidal zone, where they stay until they reach a carapace width of , and then migrate to deeper water. The growth rate in males slows from an increase in carapace width of 10 mm per year before it is 8 years old, to 2 mm per year thereafter. Females grow at about half the rate of males, probably due to the energetic demands of egg laying. Sexual maturity is reached at a carapace width of in females, and in males. Longevity is typically 25–30 years, although exceptional individuals may live up to 100 years. Distribution and ecology 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 . 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. Adults of C. pagurus are nocturnal, hiding buried in the substrate during the day, but foraging at night up to from their hideouts. Their diet includes a variety of crustaceans (including the crabs Carcinus maenas and Pilumnus hirtellus, the porcelain crabs Porcellana platycheles and Pisidia longicornis, and the squat lobster Galathea squamifera) and molluscs (including the gastropods Nucella lapillus and Littorina littorea, and the bivalves Ensis, Mytilus edulis, Cerastoderma edule, Ostrea edulis, and Lutraria lutraria). It may stalk or ambush motile prey, and may dig large pits to reach buried molluscs. The main predator of C. pagurus is the octopus, which even attacks them inside the crab pots that fishermen use to trap them. Diseases Compared to other commercially important crab species, relatively little is known about diseases of C. pagurus. Its parasites include viruses, such as the white spot syndrome virus, various bacteria that cause dark lesions on the exoskeleton, and Hematodinium-like dinoflagellates that cause "pink crab disease". Other microscopic pathogens include fungi, microsporidians, paramyxeans, and ciliates. C. pagurus is also targeted by metazoan parasites, including trematodes and parasitic barnacles. A number of sessile animals occasionally settle as epibionts on the exoskeleton of C. pagurus, including barnacles, sea anemones, serpulid polychaetes such as Janua pagenstecheri, bryozoans, and saddle oysters.