Description: Roughly square-shaped carapace reaching up to 2.5 cm. Colouration varies from a mottled orange-brown to green-black, often mottled brown. There are three teeth at either side of carapace but no teeth between the eyes, making this section almost straight. Adult males have a small patch of fur/bristles on their pincers. Walking legs have small dark spots. Ridge below the eye broken into three sections.

Habitat: Sheltered sites and soft sediments sheltered below rocks, oyster or mussel reefs and artificial structures.

Distribution: So far only reported from the SE coast of Britain.

Similar Species: Could be confused with Hemigrapsus sanguineus, 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, rather than one solid section as in H. sanguineus. 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 carb reaching 2.5 cm.
• Pincers in adult male have patch of fur/bristles.
• Three teeth each side of carapace, none between eyes.
• Walking legs have small dark spots.
• Ridge below eye is broken into three sections.

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

iNaturalist: Hemigrapsus takanoi at iNaturalist World Species Observations database.

GBIF data for Hemigrapsus takanoi

WoRMS: Hemigrapsus takanoi at World Register of Marine Species. Accepted name: Hemigrapsus takanoi Asakura & Watanabe, 2005. AphiaID: 389288.

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