Common shore crab (Carcinus maenas)

Description

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Common shore crab fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Common shore crab description

As its name suggests, the common shore crab is one of the commonest crabs on the British shore, and anyone who has gone rock-pooling is likely to have encountered one ⁽³⁾. This species is usually dark green in colour, although young individuals may have whitish blotches. The carapace of the common shore crab is wider than it is long, and the first pair of walking limbs ('pereopods') have pincers ⁽²⁾.

Size

Carapace width: 80 mm ⁽²⁾

Common shore crab biology

The diet of the common shore crab includes invertebrates such as worms, molluscs and crustaceans. Small molluscs and barnacles are taken by young crabs ⁽²⁾.

Breeding peaks in summer, and mating can only take place shortly after the female common shore crab moults; the male finds a female before she is due to moult, and carries her around underneath his body for a number of days ⁽²⁾. After the moult, copulation occurs. The female creates a cavity by burrowing in the sand; she lays the eggs whilst positioned over this cavity, attaches them to her walking legs and carries them around for several months ⁽²⁾. After hatching, the common shore crab larvae are planktonic for 2-3 years. They then settle as young crabs, and reach maturity after around a year ⁽²⁾.

Common shore crab range

The common shore crab is found around the coasts of Britain and Ireland ⁽⁴⁾. It is also common around the coasts of north-west Europe ⁽²⁾.

You can view distribution information for this species at the National Biodiversity Network Gateway.

Common shore crab habitat

The common shore crab occurs on the shore from the high water mark down to depths of around 60 metres ⁽⁴⁾, and can inhabit estuaries ⁽²⁾.

Common shore crab status

The common shore crab is common and widespread ⁽²⁾.

Common shore crab threats

The common shore crab is not currently threatened.

Common shore crab conservation

No conservation action has been targeted at the common shore crab.

There may be further information about this species available via the National Biodiversity Network Gateway.

Find out more

For more on the common shore crab, see:

• Marine Life Information Network (MarLIN) - Common Shore Crab, Carcinus maenas:
  http://www.marlin.ac.uk/species/Carcinusmaenas.htm

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Glossary

Carapace

In arthropods (insects, crabs etc), the fused head and thorax (the part of the body located near the head) also known as 'cephalothorax'.

Crustaceans

Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.

Invertebrates

Animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.

Larvae

Stage in an animal's lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Molluscs

A diverse group of invertebrates, mainly marine, that have one or all of the following; a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.

Moult

Periodic shedding of (usually) the outermost body covering (such as feathers, fur or skin) during growth and development, or at specific times of the year.

Planktonic

Aquatic organisms that drift with water movements; may be either phytoplankton (plants), or zooplankton (animals).

References

1. National Biodiversity Network Species Dictionary (January, 2003)
   http://www.nhm.ac.uk/nbn/
2. Fish, J.D. and Fish, S. (1996) A Student's Guide to the Seashore. Second Edition. Cambridge University Press, Cambridge.
3. Buczacki, S. (2002) Fauna Britannica. Hamlyn, London.
4. Pizzolla, P.F, 2002. Carcinus maenas. Common shore crab. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. (November, 2002)
   http://www.marlin.ac.uk/species/Carcinusmaenas.htm