Roux’s hermit crab (Diogenes pugilator)

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



Diogenes pugilator is a yellowish-green hermit crab. Its carapace may reach up to 11 mm in length. Like all hermit crabs it has a soft and delicate abdomen that it protects with an otherwise empty snail shell. The abdomen is asymmetrical and twisted to fit inside the shell's coil. Diogenes pugilator differs from most hermit crabs by having the left claw considerably larger than the right (and not the other way round). Both claws are covered in minute hairs. Its carapace is a square shape and has tufts of hair on the upper left and right sides.

Recorded distribution in Britain and Ireland

Occurs off the south-western coasts of Britain as far north as Anglesey and the south and west coasts of Ireland.

Global distribution



Diogenes pugilator is a benthic species usually inhabiting shallow intertidal waters down to 10 m but may less commonly be found in sandy bottom shelf areas down to about 35 m.

Depth range


Identifying features

  • Hermit crab with square carapace.
  • Tufts of hairs on upper left and right sides of carapace.
  • Anterior edge of the carapace has acute triangular lateral projections.
  • Left claw much larger than right.
  • Claws covered in hairs.
  • Eyes are half as long as the carapace is wide.

Additional information

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Listed by

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

  2. 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.]

  3. Manjon-Cabeza, M.E. & Garcia-Raso, J.E., 1998. Population structure and growth of the hermit crab Diogenes pugilator (Decapoda: Anomura: Diogenidae) from the northeastern Atlantic. Journal of Crustacean Biology, 18, 753-762

  4. McGrath, D., Costello, M.J. & Emblow, C., 2000. The hermit crab Diogenes pugilator (Roux, 1829) in Irish waters. Biology and Environment: Proceedings of the Royal Irish Academy, 100B, 115–118

  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.

  6. Rees, E.I.S., 2003. Aspects of ecology and distribution of the hermit crab Diogenes pugilator. Newsletter. Porcupine Marine Natural History Society, 12, 36-39


  1. Fenwick, 2018. Aphotomarine. Occurrence dataset Accessed via on 2018-10-01

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

  3. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2024-06-12

  4. South East Wales Biodiversity Records Centre, 2018. SEWBReC Myriapods, Isopods, and allied species (South East Wales). Occurrence dataset: accessed via on 2018-10-02.


This review can be cited as:

Barnes, M.K.S. 2008. Diogenes pugilator Roux’s hermit 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 12-06-2024]. Available from:

Last Updated: 13/05/2008