Shore crab

This crab is common around all of the UK. If you've ever been rockpooling or crabbing, it's probably the shore crab that you've met.

Scientific name

Carcinus maenas

When to see

January to December

Species information

Category

Statistics

Shell width: Up to 9cm

Conservation status

Common

Habitats

About

The shore crab is the most common crab encountered on our shores. Normally a green-ish colour, shore crabs are easily found in rockpools or on the end of crab lines dangled into shallow waters. They aren't exactly picky eaters and will feast on anything and everything they come across, including seaweed, mussels, barnacles and even smaller crabs. If you spot a crab with an orange mass on its stomach, don't be alarmed, they are eggs! Females carry the fertilised eggs with them to protect them from predators. A female with eggs is known as "berried". Although a native species here, the shore crab has become an invasive species in many other parts of the world, including Australia, South Africa and California.

How to identify

The most common crab on our beaches, normally green-ish in colour but it can be orange or even red. It is medium sized and can be identified by the pattern of spikes on its shell (carapace). The shore crab has five upturned spikes on each side of the carapace and 3 rounded lobes between the eyes (5,3,5). The different colourations are related to the crab's age and whether it is breeding season.

Distribution

Found around all UK coasts.

Did you know?

The shore crab sometimes falls victim to one of nature's weirdest parasites. The crab hacker barnacle lands on the shore crab and castrates it, before using it as a host to carry the barnacle's eggs instead! You can tell a parasitised shore crab as they have a smooth pale mass on their underside, exactly where a female would normally carry her mass of orange eggs!