A sea slug (Trinchesia foliata)

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



Trinchesia foliata typically grows to 1 cm in length and has five red markings on its head/heart region. The body and processes (cerata) are flecked with yellowish-white pigments that fade towards the base. Rings of colour are formed just below the tips of the short pointed cerata. Cerata are organized in seven to eight rows, each having up to 5 cerata across. The front tentacles and horn-like structures (rhinophores) have red rings on them and crescent-shaped red marks are also located in front of and behind the bases of these tentacles. There is a red V-shaped mark behind the heart in the centre of the back.

Recorded distribution in Britain and Ireland

Recorded from the Isles of Scilly; the Mouls, Cornwall; Bantry Bay; Strangford Lough; Island of Mull, the Western Isles and north west Scotland.

Global distribution

Recorded from the Faeroes, Norway and the Mediterranean.


Occurs beneath loose stones on the shore as well as in the sublittoral.

Depth range


Identifying features

  • Grows to around 1 cm in length.
  • Body has yellowish-white flecks with 5 reddish-orange patches on the head.
  • There is a red V-shaped mark in the centre of the back.

Additional information

Feeds on a variety of hydroids. Trinchesia foliata is often confused with Trinchesia (syn. Cuthona) genovae. Mediterranean records of Tenellia foliata was shown to be the similar species Trinchesia (syn. Cuthona) genovae (Picton & Morrow, 1994).

Listed by

- none -


  1. Hayward, P.J. & Ryland, J.S. (ed.), 1995. The marine fauna of the British Isles and north-west Europe. Volume 2. Molluscs to Chordates. Oxford Science Publications. Oxford: Clarendon 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. JNCC (Joint Nature Conservation Committee), 1999. Marine Environment Resource Mapping And Information Database (MERMAID): Marine Nature Conservation Review Survey Database. [on-line] http://www.jncc.gov.uk/mermaid

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

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


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

  2. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2024-04-21


This review can be cited as:

Edwards, R.V. 2007. Trinchesia foliata 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 21-04-2024]. Available from: https://www.marlin.ac.uk/species/detail/1988

Last Updated: 07/06/2007