Description: Swimming crab reaching a carapace size of around 37 mm. Carapace usually coloured greenish brown or greenish grey, often with a row of white spots on each side. Paddle of swimming legs is blue. Surface of carapace is relatively smooth, sometimes with occasional granular sections. Three teeth on frontal lobe (between the eyes), the outer two are equal in size and the middle one is the longest. Five teeth on either side of carapace, with the fourth ‘sharper’ than the others. Pincers equal in length and there is a V-shaped groove and tubercles on some of the sections of the pincers.

Habitat: Found from rockpools on the lower shore to around 90 m, on sand or gravel.

Distribution: Found all around Britain and Ireland

Similar Species: Could be confused with other Polybius species. Very similar to Polybius depurator, teeth on frontal lobe are a key characteristic, as are the tubercles and grooves on sections of the pincers.

Key Identification Features:

• Carapace greenish brown to greenish grey, often with a row of white spots on each side.
• Three teeth on frontal lobe, with the middle one being the longest.
• Five teeth on each side of carapace, the fourth is the ‘sharpest.’
• V-shaped grooves and tubercles on some sections of pincers.

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

iNaturalist: Polybius holsatus at iNaturalist World Species Observations database.

WoRMS: Polybius holsatus at World Register of Marine Species. Accepted name: Polybius holsatus (Fabricius, 1798). AphiaID: 1748246.

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