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

Common sea slater (Ligia oceanica)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.
Only coastal and marine records shown



Ligia oceanica is the largest of the oniscid isopods, up to 3 cm in length, and has large eyes similar to the compound eye of insects. It is oval shaped, dorso-ventrally flattened and the body is twice as long as broad. The antennae are approximately two thirds the length of the body. The head and first thoracic segment are fused into a cephalothorax, leaving seven externally visible thoracic segments. Ligia oceanica possess seven pairs of walking legs (pereopods) of similar appearance. Two large uropods project from the posterior margin of the telson, each with two long processes or rami. The colouration of Ligia oceanica varies in shade from grey to olive.

Recorded distribution in Britain and Ireland

Ligia oceanica is abundant and widespread around the British coast, wherever rock substrata are present.

Global distribution



Abundant on rocky coasts within the terrestrial and littoral fringe, especially common in crevices, rock pools and under stones.

Depth range


Identifying features

  • Body twice as long as broad.
  • Dorso-ventrally flattened body.
  • At least 10 segments on antennal flagellum.
  • Seven externally visible thoracic segments.
  • Large, up to 3 cm in length.
  • Large eyes

Additional information

Ligia oceanica are omnivorous, their diet consisting of shore debris such as decaying seaweed and encrusting diatoms.

Listed by

- none -

Further information sources

Search on:


  1. Fish, J.D. & Fish, S., 1996. A student's guide to the seashore. Cambridge: Cambridge University Press.

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

  3. Hopkin, S., 1991. A key to the woodlice of Britain & Ireland. Preston Montford: Field Studies Council. [AIDGAP key 204.]

  4. Oliver, P.G. & Meechan, C.J., 1994. Woodlice. Keys and Notes for the Identification of the Species. Synopses of the British Fauna (New Series). The Linnean Society of London: Academic Press. [Synopses of the British Fauna, no. 49.]


This review can be cited as:

Ballerstedt, S. 2005. Ligia oceanica Common sea slater. 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 19-09-2018]. Available from:

Last Updated: 15/09/2005