information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

Arch-fronted swimming crab (Liocarcinus navigator)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.



The carapace of Liocarcinus arcuatus is as long as it is broad (up to 30 mm in length and 30 mm in breadth), with 5 sharp teeth posterior to the eyes on each side. The frontal margin between the eyes is hairy and without teeth. The carapace is gently convex with minute transverse ridges. It is brown in colour and the limbs are somewhat paler.

Recorded distribution in Britain and Ireland

Liocarcinus arcuatus is a southerly species found on south and west coasts of the British Isles, and at Flamborough Head.

Global distribution



Found on mixed sandy substrata from the shallow sublittoral to offshore (2-108 m).

Depth range


Identifying features

  • The 5 anterolateral teeth on the carapace are very unequal, with the 3rd and 5th being larger than the others.
  • The dactyls of the 5th walking legs are sharply pointed and fringed with hairs on both sides.

Additional information

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Listed by

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Further information sources

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  1. Crothers, J. & Crothers, M., 1988. A key to the crabs and crab-like animals of British inshore waters. Somerset, England: Field Studies Council. [AIDGAP guide, no. 155.]

  2. Hayward, P., Nelson-Smith, T. & Shields, C. 1996. Collins pocket guide. Sea shore of Britain and northern Europe. London: HarperCollins.

  3. Hayward, P.J. & Ryland, J.S. (ed.) 1995b. Handbook of the marine fauna of North-West Europe. Oxford: Oxford University Press.

  4. Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]

  5. Ingle, R.W., 1980. British Crabs. Oxford: British Museum (Natural History), Oxford University Press.

  6. National Biodiversity Network (NBN) Atlas website. Available from:  Accessed 01 April 2017


This review can be cited as:

Skewes, M. 2005. Liocarcinus navigator Arch-fronted swimming crab. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 25-09-2018]. Available from:

Last Updated: 17/11/2005