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Crab

Shore Crab

Carcinus maenas

Carcinus maenas (Linnaeus, 1758) · Carcinidae WoRMS 107381

Reference photos

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A very common crab found on all shores of Britain and Ireland, from high water down to 60 m. The shell is much broader than long, with five sharp teeth either side of the eyes and three rounded lobes between them. Colour is highly variable, most often mottled olive green to dark brown, but sometimes orange or red. The walking legs end in points, and the last segment of the rear legs is flattened but never expanded into a swimming paddle.

Depth

Intertidal down to 60 m, mostly on the shore and in shallow water

Size

Shell (carapace) commonly 4-8 cm wide, with males recorded to 86 mm across

Habitat

All types of shore from high water down to 60 m; especially abundant in estuaries and salt marshes, and on sheltered rocky shores

Behaviour

Walks over the bottom as an omnivorous predator and scavenger; peak foraging at night around high tide, with green individuals sheltering under algae

Diet

I eat

  • A true omnivore, taking molluscs, other crustaceans, worms, algae and carrion
  • Large crabs feed mainly on molluscs, with the common mussel the single most important prey
  • On rocky shores the young take barnacles, while adults take more gastropods, especially dogwhelks and winkles

Eats me

Where you'd find it

Found around most of Britain and Ireland, though less often in the Celtic Sea and the waters west of Ireland.

ChannelCeltic SeaNorth SeaIrish SeaW of IrelandW of Scotland
Often seenNow and thenWhere PEBL filmsBased on marine survey records (OBIS). Blank seas can mean nobody has looked there, not that the animal is absent.

Sources

Open-access references behind this page. Every statement on this page was read out of one of them; anything that could not be traced to a source was taken off the page rather than left standing. Each link was checked on the date shown, and confirmed then to be about this species.

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