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Shore crab

Shore crab by North East WildlifeShore crab by North East Wildlife
Scientific name

Shore crab (Carcinus maenas). 

Habitat

Look out for shore crabs in rock pools and amongst seaweed on the rocky shore along the coast of the North York Moors National Park. 

Appearance

Shore crabs vary in colour but are often dark green or brown. They also vary in size, but can measure up to 9cm across the top of their shell or carapace. The edge of the carapace has three rounded dents or lobes between the eyes and five points down the side behind the eyes. 

Young shore crabs can have white, red or black markings on the carapace. Female crabs have a wide triangle shaped flap on the underside of their shell and can often be found carrying eggs here. Males have a narrower flap on the underside of their shell. 

Lifestyle

Shore crabs are scavengers and eat anything, alive or dead! They are fierce predators and have ferocious claws that can give human fingers a nasty nip. 

As the shore crab grows, it sheds its old shell and exposes a new shell that has been growing underneath. The crab takes in water to enlarge the new shell before it hardens. While the new shell is soft the crab would make a tasty meal for many predators so it hides itself away under a rock. 

After a pair of crabs has mated, the female carries the eggs around underneath her body for up to 18 weeks before they hatch. The baby crabs, or larvae, float around in the sea for many weeks before they sink to the sea bed as adults. 

Conservation

The shore crab is one of the commonest crabs found around our coastline. In Britain, we don’t tend to eat shore crabs, but they are eaten in other places in Europe.