Brown crab
The brown, or edible, crab (Cancer pagurus) is an indigenous species in mainland Norway. It is found in significant numbers along the Norwegian coastline. Today, the brown crab is viewed as a species with the potential to establish a population at Svalbard/Spitsbergen, where it has not been living before. It is assumed that the brown crab is getting to Svalbard through ballast water. Considering there is a moderate potential for invasion on Svalbard and no known ecological impact, the brown crab is viewed as a Low impact (LO) species by the Alien Species List of Norway.
The brown crab has an oval, red-brown carapace with an uneven edge in the front. The crab has five walking legs, where the front pair bears large claws with black tips. Unlike other crustaceans, the hind body is greatly reduced, and folded in under the chest.
The brown crab lives both on soft and hard bottoms. It can often be observed partly hidden in the sand, as well as in small holes under and in-between rocks. The brown crab is often found in shallow waters during the summer, as this crab prefers temperate waters. During the winter the crab migrates to deeper waters (30-50 m), where the temperature keeps at least 4 C°.
In order for a crab to grow, it needs to moult – change the shell. An adult brown crab can weigh up to 5 kg. They are not picky eaters but prefer mussels and bristle worms. Brown crabs can often be found in kelp forests, as it both provides good hiding spots as well as plenty of food.
The brown crab is valued by humans for its taste, and it is important commercially.