Description: Previously known as Maja squinado which is now known to be a Mediterranean species. This is a large spider crab that is often very well camouflaged by epifaunal growth on its carapace. It is the biggest spider crab found in Britain or Ireland reaching a carapace size of up to 22 cm. The carapace is quite circular to oval and has large prominent spines all around its outer edge. There are smaller less prominent spines on the rest of the carapace. There are two distinct spines between the eyes. The pincers are long but the claws relatively small. The other four pairs of legs are covered in hairs, are long and taper to darker coloured tip.

Habitat: Very low shore to around 50 m depth. Prefers rocky areas or areas of coarse sand.

Distribution: A southern species in Britain and Ireland. Now quite frequent in Northern Ireland but unknown from there in the early 1980s, it is probably expanding its range northwards.

Similar Species: Carapace shape is distinctive but juveniles could potentially be confused with other spider crabs.

Key Identification Features:

• Large spider crab, reaching up to 22 cm.
• Circular to oval carapace, with prominent spines around outer edge.
• Smaller spines covering the rest of the carapace.
• Two distinct spines between the eyes.
• Usually covered in other life - algae, hydroids etc. - so can be hard to see or make out.

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

iNaturalist: Maja brachydactyla at iNaturalist World Species Observations database.

GBIF data for Maja brachydactyla

WoRMS: Maja brachydactyla at World Register of Marine Species. Accepted name: Maja brachydactyla Balss, 1922. AphiaID: 107347.

Classification: Biota; Animalia; Arthropoda; Crustacea; Multicrustacea; Malacostraca; Eumalacostraca; Eucarida; Decapoda; Pleocyemata; Brachyura; Eubrachyura; Heterotremata; Majoidea; Majidae; Majinae; Maja