Common shore crab  (Carcinus maenas)

Common shore crab
Common shore crab
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Facts

KingdomAnimalia
PhylumArthropoda
ClassCrustacea
OrderDecapoda
FamilyPortunidae
GenusCarcinus (1)
SizeCarapace width: 80 mm (2)
Learn about the scientific name of this species and how it fits into the tree of life at Nature Navigator.

Status

Common and widespread (2).

Description

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

Range

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.

Habitat

Found on the shore from the high water mark down to depths of around 60 m (4), and can inhabit estuaries (2).

Biology

The shore crab feeds on invertebrates including 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 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 larvae are planktonic for 2-3 years. They then settle as young crabs, and reach maturity after around a year (2).

Threats

Not currently threatened.

Conservation

No conservation action has been targeted at this species.

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

Find out more

For more on this species see the Marine Life Information Network (MarLIN) species account, available from:
http://www.marlin.ac.uk/species/Carcinusmaenas.htm

Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact: arkive@wildscreen.org.uk

Glossary

  • Carapace: the top shell of a turtle. In arthropods (insects, crabs etc), the fused head and thorax (the part of the body located near the head) also known as 'cephalothorax'.
  • 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.
  • 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
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