Wild Wednesday – Common shore crab | Latest news

The common shore crab, scientific name, Carcinus maenas, is a widely distributed species of crab found along our shores and are highly adaptable to different coastal environments.

They are easily found in rockpools or on the end of crab lines dangled into shallow waters. They might not be especially large but are very active and can be quite aggressive if under threat, so watch out if you go crabbing!

Shore crabs are generally active at night (nocturnal) and hide in crevices, under rocks, or within seaweed during the day to avoid predators.

These crabs have a distinctive greenish-brown carapace (shell) that is often mottled with darker spots. Their claws are typically larger on one side than the other, with the larger claw often being darker.

Adult common shore crabs can grow to around ten centimetres (four inches) across the shell. They typically live around three to four years in the wild, although their lifespan can vary depending on environmental factors.

At the front of shell, are five jagged teeth either side of the eyes, with three rounded lobes between the eyes. These will be variable in colour from dark green to orange or red.

They are opportunistic feeders and will eat a wide range of food, including small fish, molluscs, algae, worms and other invertebrates (animal without a backbone). They can even scavenge for dead animals. 

Female common shore crabs lay thousands of eggs, which hatch into larvae that go through several stages of development before becoming juvenile crabs.

While they are opportunistic hunters, common shore crabs themselves are preyed upon by a range of animals, including seabirds, fish, and humans.

These crabs play an important role in the ecosystem, especially in terms of nutrient cycling and as a food source for other animals.

Read more here: Shore crab | The Wildlife Trusts