Biodiversity & Conservation

Scorpion spider crab - Inachus dorsettensis

Inachus dorsettensis

Image Paul Newland - Inachus dorsettensis in front of snakelocks anenome. Image width ca 15 cm.
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Distribution map

Inachus dorsettensis recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

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Inachus dorsettensis is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Arthropoda Arthropods, joint-legged animals, e.g. insects, crustaceans & spiders
Class Malacostraca Crabs, lobsters, sand hoppers and sea slaters
Authority (Pennant 1777)
Recent synonyms None
Map icon Recorded Distribution in Britain and Ireland Widely distributed around the British Isles with sparse records along the east coast of England and west coast of Ireland.
Habitat information icon Habitat information Inachus dorsettensis occurs in coastal waters from about 4 m to at least 300 m offshore on various substrates such as sand, muddy sand and seaweed-covered rocky beds.
Text page icon Description Inachus dorsettensis has a triangular shaped shell (carapace) with long slender legs and a U-shaped snout-like projection (rostrum). It has four small spines on the anterior part of carapace upper surface. The carapace is reddish brown in colour. The underside of the claw bearing limb (cheliped) is bright pink or violet in colour especially the segment behind the claw (the carpus). Female chelipeds are small and the claw (propodus) is somewhat compressed. Male chelipeds are large, with a short and swollen propodus. The carapace length is around 3.5 cm, with a breadth of 2.7 cm. The eye stalks are also totally visible from above.
Identifying features
  • Chelipeds equal in size.
  • Carapace triangular, and longer than broad.
  • U-shaped cleft separating each half of the rostrum.
  • Well developed spines ranging across the anterior part of the carapace.
Additional information icon Additional information Inachus dorsettensis covers itself in tiny pieces of sponge and sea weed to provide camouflage. It is often found living in the tentacles of the snakelocks anemone (see Ingle, 1996 for further details).

This review can be cited as follows:

Rose Edwards 2005. Inachus dorsettensis. Scorpion spider crab. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 19/06/2013]. Available from: <http://www.marlin.ac.uk/speciesinformation.php?speciesID=3561>