Toad crab (Hyas coarctatus)

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



The toad crab, Hyas coarctatus, is a 'true crab' and therby has a heavily calcified, flattened carapace with a short abdomen folded up beneath it. The first appendages form large claws. It is a member of the spider crab family and has long, thin legs, and claws of the same length as the legs. Its stalked eyes are visible from above. Hyas coarctatus can reach up to 61 mm in carapace length and is reddish-brown above and white underneath. It has longer claws than the giant spider crab, Hyas araneus, and the two forward-projecting horns on its head are slightly longer and further apart than those of the giant spider crab.

Recorded distribution in Britain and Ireland

Found throught the British Isles but absent from the west coasts of Ireland.

Global distribution



The toad crab is a benthic species found on both hard and sandy bottoms from the intertidal region down to a depth of up to 50 m.

Depth range


Identifying features

  • Spider crab up to 61 mm in carapace length.
  • Cornea of the retracted eye is visible from above and not concealed under the orbit.
  • Post-orbital spine is flattened and expanded laterally.
  • Basal antenna segment is less than twice as long as it is wide.
  • Abdominal region is dilated laterally and, with the post-orbital region, forms a harp-shaped shelf.

Additional information

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Listed by

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  1. Dyer, M.F., 1985. The distribution of Hyas araneus (L.) and Hyas coarctatus Leach (Crustacea: Decapoda: Brachyura) in the North Sea and the Svalbard region. Journal of the Marine Biological Association of the United Kingdom, 65, 195-201

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

  3. 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.]

  4. Ingle, R., 1997. Crayfishes, lobsters and crabs of Europe. An illustrated guide to common and traded species. London: Chapman and Hall.

  5. Picton, B.E. & Costello, M.J., 1998. BioMar biotope viewer: a guide to marine habitats, fauna and flora of Britain and Ireland. [CD-ROM] Environmental Sciences Unit, Trinity College, Dublin.


  1. Centre for Environmental Data and Recording, 2018. Ulster Museum Marine Surveys of Northern Ireland Coastal Waters. Occurrence dataset accessed via on 2018-09-25.

  2. Environmental Records Information Centre North East, 2018. ERIC NE Combined dataset to 2017. Occurrence dataset: accessed via on 2018-09-38

  3. NBN (National Biodiversity Network) Atlas. Available from:

  4. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2024-05-18


This review can be cited as:

Barnes, M.K.S. 2008. Hyas coarctatus Toad crab. In Tyler-Walters H. and Hiscock K. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 18-05-2024]. Available from:

Last Updated: 07/04/2008