Description: Medium-sized swimming crab reaching a size of up to 45 mm aross the carapace. Reddish-brown in colour, occasionally with yellow or red patches, the carapace bears prominent grooves (giving this crab its common name, wrinkled swimming crab). Five evenly developed pointed teeth on each side of the carapace. Legs have a ridge from body to tip. Swimming paddle at the tip of the fifth pair of legs has a ridge in the middle and is pointed at the tip.

Habitat: Coarse sand and gravel from shore to 100 m depth. Occasionally reported on maerl too.

Distribution: Found around most coasts of Britain and Ireland.

Similar Species: Could be confused with other Polybius sp.

Key Identification Features:

• Reddish-brown carapace with prominent ‘wrinkles’ or grooves.
• Five evenly-developed, pointed teeth at each side of carapace.
• Legs bearing a ridge from body to tip.
• Rearmost set of legs ends in a pointed swimming paddle, also bearing a ridge.

Distribution Map from NBN: Polybius corrugatus at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Polybius corrugatus at iNaturalist World Species Observations database.

WoRMS: Polybius corrugatus at World Register of Marine Species. Accepted name: Polybius corrugatus (Pennant, 1777). AphiaID: 1752528.

Classification: Biota; Animalia; Arthropoda; Crustacea; Multicrustacea; Malacostraca; Eumalacostraca; Eucarida; Decapoda; Pleocyemata; Brachyura; Eubrachyura; Heterotremata; Portunoidea; Polybiidae; Polybius