Description: A medium sized crab with a roughly square-shaped carapace, reaching a size of just over 4 cm. Colouration varies from orange-brown to green-black, often mottled. There are three sharply pointed teeth at either side of carapace but no teeth between the eyes, making this section almost straight. The pincers have white tips and reddish coloured spots on their upper surface, although these can be purple or brown. Walking legs are striped. Ridge below the eye one solid line.

Habitat: Reported from exposed rocky shores and in soft sediments sheltered below rocks, oyster or mussel reefs and artificial structures.

Distribution: So far only recorded as far north as Wales.

Similar Species: Could be confused with Hemigrapsus takanoi, especially when juvenile as H. takanoi doesn’t grow as large. Teeth at side of carapace are more pointed in H. sanguineus, and H. takanoi lacks reddish spots on pincers. The ridge below the eye in H. takanoi is broken into three distinct sections. Could also be confused with Carcinus maenas but it has 5 teeth on each side of carapace and 3 lobes between the eyes.

Key Identification Features:

• Roughly square-shaped crab reaching just over 4 cm.
• Reddish spots on upper surface of pincers (can also be purple or brown).
• Three pointed teeth each side of carapace, none between the eyes.
• Walking legs are striped/banded.
• Ridge below the eye is one solid line.

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

iNaturalist: Hemigrapsus sanguineus at iNaturalist World Species Observations database.

GBIF data for Hemigrapsus sanguineus

WoRMS: Hemigrapsus sanguineus at World Register of Marine Species. Accepted name: Hemigrapsus sanguineus (De Haan, 1835). AphiaID: 158417.

Classification: Biota; Animalia; Arthropoda; Crustacea; Multicrustacea; Malacostraca; Eumalacostraca; Eucarida; Decapoda; Pleocyemata; Brachyura; Eubrachyura; Thoracotremata; Grapsoidea; Varunidae; Varuninae; Hemigrapsus