A sea slug (Trapania pallida)

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



A sea slug that grows up to 15 mm in length. It is translucent white in colour with white patches on many parts of the body and appendages. The skin is smooth and the oral tentacles are long and finger-like.

Recorded distribution in Britain and Ireland

South-west England, west coast of Ireland, the Isle of Man, and Loch Sunart and Loch Broom approaches in the west of Scotland.

Global distribution



Found amongst bryozoans, hydroids and sponges on rocky sublittoral cliffs and outcrops, in depths of 10-20 m.

Depth range


Identifying features

  • Lateral processes directed posteriorly from the bases of the rhinophores and another pair alongside the gills.
  • Three tripinnate gills anterior to the anal papilla.
  • Conspicuous pair of propodial tentacles.
  • White patches on rhinophores, processes, gills and tail.

Additional information

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  1. 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.]

  2. Picton, B. E. & Morrow, C.C., 1994. A Field Guide to the Nudibranchs of the British Isles. London: Immel Publishing Ltd.

  3. Thompson, T. E. & Brown, G. H., 1976. British Opisthobranch Molluscs. London: Academic Press. [Synopses of the British Fauna, no. 8.]


  1. Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) data for Great Britain and Ireland - restricted access. Occurrence dataset: https://doi.org/10.15468/4bsawx accessed via GBIF.org on 2018-09-25.

  2. Conchological Society of Great Britain & Ireland, 2018. Mollusc (marine) records for Great Britain and Ireland. Occurrence dataset: https://doi.org/10.15468/aurwcz accessed via GBIF.org on 2018-09-25.

  3. Fenwick, 2018. Aphotomarine. Occurrence dataset http://www.aphotomarine.com/index.html Accessed via NBNAtlas.org on 2018-10-01

  4. NBN (National Biodiversity Network) Atlas. Available from: https://www.nbnatlas.org.

  5. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2024-06-20


This review can be cited as:

Wilson, E. 2002. Trapania pallida A sea slug. 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 20-06-2024]. Available from: https://marlin.ac.uk/species/detail/1246

Last Updated: 11/10/2002