Velvet Swimming Crab

Velvet crabs have a dark, flattened carapace which ranges from black to brown in colour and is usually around 6.5 cm long and up to 10 cm across, weighing up to 250 grams. The carapace is pubescent with short yellowish hairs providing a velvety texture. Tubercles are scattered across the upper surface, with a higher concentration towards the front. The frontal part of the crab's underside has some tubercles as well and is densely hairy. The front of the carapace is mostly straight and bends slightly inwards at the centre line; the front edge bears seven to ten tooth-like indentations. The claw-bearing legs (the chelipeds) also have short hairs and are of equally short length. The "wrist" is armed with a spine on its outer side.

In the British Isles, velvet crabs are found from Orkney around Scotland, England, Wales, and Ireland. They also live in the nearby German Bight and in parts of the West Frisian Islands.

In France, velvet crabs are considered a delicacy. Fisheries in south Brittany, France's main producers of velvet crabs, suffered in the late 20th century due to mass mortality events; between 1984 and 1988 the catch dropped by 96%. The decline was attributed to infections by dinoflagellates which a 1996 investigation tentatively identified as belonging to the genus Hematodinium.