information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

Common spider crab (Maja brachydactyla)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.
Only coastal and marine records shown



The largest spider crab in the British Isles. The common spider crab is red, brownish-red, or yellowish in colour and the body is up to 20 cm long. It has a circular to oval shell (carapace), broad at the back and narrow at the front. Strong tapering spines border the shell, while the rest of the shell bears smaller spines. The small eyes are either side of two distinct frontal spines. The legs are covered by hairs. The first pair of legs bear small claws while the rest taper to stout, dark tips. The shell is usually covered with algae.

Recorded distribution in Britain and Ireland

Found in south and west Britain and Ireland, this species is thought to be extending its range further North in scotland.

Global distribution



Found at extreme low water to around 50 m, Maja brachydactyla inhabitats rocky or coarse sandy areas.

Depth range


Identifying features

  • Carapace strongly convex, both transversely and longitudinally.
  • Dorsal surface with many short and acute spines.
  • Frontal region produced as a stout, short, bifid rostrum each half conspicuously diverging outward or almost parallel.
  • Chelipeds equal and along with second to fifth pairs of pereiopods, moderately stout, segments with spinules.

Additional information

Maja brachydactyla was until recently considered to be conspecific with Maja squinado. Maja squinado has a Mediterranean distribution, while Maja brachydactyla is found in the northeast Atlantic Ocean from Morrocco to Scotland.

Listed by

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Further information sources

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    This review can be cited as:

    Hosie, A.M. 2009. Maja brachydactyla Common spider crab. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 19-09-2018]. Available from:

    Last Updated: 09/01/2009