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

Lesser gooseberry sea squirt (Distomus variolosus)

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



This colonial sea squirt forms an encrusting mat of closely grouped zooids that are united at the base or side but are mostly free. The zooids are cylindrical or ovoid, up to 1 cm high, and are red to brown in colour. Both siphons are found at the upper end of the zooid.

Recorded distribution in Britain and Ireland

Distomus variolosus has been recorded in west Sussex, south Devon and Cornwall, Lundy, south and south-west Wales, south-east and western Ireland, north Wales, Isle of Man and the sound between Gighay and Hellisay in the Outer Hebrides.

Global distribution

Distomus variolosus is recorded south of the British Isles to Portugal.


Distomus variolosus is found on rocks, stones, around the bases of hydroids and on macroalgae, especially on the holdfasts of Laminaria hyperborea.

Depth range


Identifying features

  • Closely grouped cylindridal or ovoid zooids, up to 1 cm high.
  • Zooids united at base or side but mostly free.
  • Red to brown in colour.
  • Both siphons at upper end of each zooid.

Additional information

Distomus variolosus may be confused with the baked bean ascidian, Dendrodoa grossularia, or another sea squirt Stolonica socialis. The internal anatomy is important when distinguishing between species. However, the siphons of Dendrodoa grossularia are more conspicuous than those of Distomus variolus (Millar, 1970).

Listed by

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Further information sources

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  1. Berrill, N.J., 1950. The Tunicata with an account of the British species. London: Ray Society.

  2. Gibson, R., Hextall, B. & Rogers, A., 2001. Photographic guide to the sea and seashore life of Britain and north-west Europe. Oxford: Oxford University Press.

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

  4. 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.]

  5. JNCC (Joint Nature Conservation Committee), 1999. Marine Environment Resource Mapping And Information Database (MERMAID): Marine Nature Conservation Review Survey Database. [on-line]

  6. Millar, R.H., 1970. British Ascidians London: Academic Press.[Synopses of the British Fauna, no. 1.]

  7. 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. Dorset Environmental Records Centre, 2018. Ross Coral Mapping Project - NBN South West Pilot Project Case Studies. Occurrence dataset: accessed via on 2018-09-25.

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

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

  4. OBIS (Ocean Biogeographic Information System),  2021. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2021-05-06

  5. South East Wales Biodiversity Records Centre, 2018. SEWBReC Marine and other Aquatic Invertebrates (South East Wales). Occurrence dataset: accessed via on 2018-10-02.


This review can be cited as:

Ager, O.E.D. 2006. Distomus variolosus Lesser gooseberry sea squirt. 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 06-05-2021]. Available from:

Last Updated: 19/09/2006