Description: Swimming crab reaching a carapace size of around 40 mm. Carapace usually coloured red-brown to dark red with almost semi-circular bands of white spots on each side. Paddle of swimming legs is blue. Surface of carapace covered in small grooves and bumps, more noticeable towards the rear of the carapace. Teeth on frontal lobe equal and do not protrude far. Five teeth on either side of carapace, all five teeth are prominent and pointed, with the fifth ‘sharper’ than the others. Pincers equal in length.

Habitat: Sand, muddy sand and gravel from around 5 m to over 200 m.

Distribution: Found around all coasts of Britain and Ireland. Commonly recorded.

Similar Species: Could be confused with other Polybius sp. Possibly over-recorded due to some guidebooks only featuring this species. Similar to Polybius holstatus, teeth on frontal lobe are distinct.

Key Identification Features:

• Dark red-brown with a band of white spots on each side of carapace.
• Surface of carapace covered in small grooves and bumps, more noticeable towards bottom,
• Five pointed teeth on each side of carapace.
• Fifth teeth appear ‘sharper’ than the others (narrower).
• Three equal teeth between eyes.

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

iNaturalist: Polybius depurator at iNaturalist World Species Observations database.

GBIF data for Polybius depurator

WoRMS: Polybius depurator at World Register of Marine Species. Accepted name: Polybius depurator (Linnaeus, 1758). AphiaID: 1750291.

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