Description
The carapace of the swimming crab is smooth and often a little bit shiny. There are three teeth between the eyes, of which the middle on is larger than the other two. They have a long sharp spine on the inside of the first pair of legs, at the joint of the claw. On the outside there is a smaller spine. Along the legs there they have a row of small hairs, that can be seen clearly on the last pair (paddle). The claws have smell organs that are useful for finding worms, echinoderms and crustaceans where they feed on. In the winter they move to deeper water.

Size
The maximum width of the carapace is 57 mm, usually these animals are not larger than 35 mm.

Colour
The carapace has a light colour, light-brown, greenish-brown, greyish-brown, greyish-bleu or greyish-green. The carapace often has white lines or spots. The legs often have an orange shine.

Habitat
In common with the blue-leg swimming, it lives on soft substrata where it can bury it self. From the tidal zone to a depth of 100 m.

Distribution
North eastern Atlantic from Norway till Morocco. No reliable records from the Mediterranean.