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

A sea slug (Eubranchus farrani)

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



Eubranchus farrani is very variable in colour. It usually has a translucent white body, with orange tipped rhinophores and oral tentacles. The white inflated cerrata have conspicuous sub-terminal orange or yellow rings. Some colour variants show individual exaggeration of certain markings. Others may have orange blotches ringed with blue. An all white form is common. Juveniles may have no colour other than pale brown or salmon pink. The cerrata are arranged in up to 10 diagonal rows of up to 5 cerrata in each half row. Oral tentacles and rhinophores are similar in size and relatively short. The maximum length for Eubranchus farrani is 2 cm.

Recorded distribution in Britain and Ireland

Recorded from most British coasts.

Global distribution

Recorded from Norway and the Atlantic coast of France, to the western Mediterranean Sea.


Found on rocky shores in the shallow sublittoral down to 30 m. Feeds on thecate hydroids such as Obelia geniculata.

Depth range


Identifying features

  • Up to 2 cm extended length.
  • Typical coloration is translucent white body with orange tipped rhinophores and oral tentacles.
  • Other colour morphs exist.
  • Cerrata arranged in up to 10 diagonal rows of up to 5 cerrata in each half row.
  • Oral tentacles and rhinophores are similar in size and relatively short.
  • Broad propodial part of foot projects on each side of the head.

Additional information

The spawn is a laid in a spiral ribbon of about 2 turns, flared out on its upper margin. Eubranchus farrani has in the past been confused with Eubranchus tricolour. However, Eubranchus farrani is more slender and smaller, with fewer cerata of less compressed shape, and different colour patterns (Thompson & Brown, 1984).

Listed by

- none -

Further information sources

Search on:


  1. Hayward, P., Nelson-Smith, T. & Shields, C. 1996. Collins pocket guide. Sea shore of Britain and northern Europe. London: HarperCollins.

  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]

  4. MarLIN (Marine Life Information Network), 2005. SEArchable BEnthic Data (SEABED) Map [on-line]. Data Access Sub-programme, Marine Life Information Network for Britian and Ireland,

  5. National Biodiversity Network (NBN) Atlas website. Available from:  Accessed 01 April 2017

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

  7. Rudman, W.B., 2003. Eubranchus farrani [on-line].,

  8. Thompson, T.E. & Brown, G.H., 1984. Biology of Opisthobranch Molluscs, vol. II. London: Ray Society.


This review can be cited as:

Oakley, J.A. 2008. Eubranchus farrani A sea slug. 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 21-07-2018]. Available from:

Last Updated: 24/04/2008