Carapace slightly broader than long, dorsal surface tuberculate, tubercles prominent on posterior half; protogastric region concave, posterior epibranchial and anterior mesobranchial particularly elevated, cardiac swollen. Third maxilliped narrowing anteriorly. Antero-lateral margins of carapace proximally sinuous, distally convex and tuberculate. Chelipeds equal in size, pereiopods 2-5 tuberculate; abdominal segments 3-6 fused. Male chelipeds longer and more robust than in female; apex of first pleopod with a crown of spines.
Carapace length up to 13 (17) mm.
Depth range from rarely intertidal to 150 metres. Common, on gravel and stony bottoms. Probably ovigerous throughout year, larvae from January-November.
Variable, carapace and pereiopods light yellowish-orange to deep reddish-brown, sometimes with white bands or spots.
Shetland, Orkney, Moray Firth, Aberdeen, Firth of Forth, Northumberland, Yorkshire, East Channel, Wight, Portland, Channel Isles, Plymouth, Scilly Isles, Bristol Channel, Isle of Man, Dublin, Belfast, Clyde & Argyll, Mayo, Galway Bay, Fastnet, Cork.