MarLIN

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

A sea squirt (Ascidia conchilega)

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

Summary

Description

Ascidia conchilega is a sessile, solitary sea squirt that grows to up to 6 cm in length and is greenish in colour. It has an elongate, oval-shaped body that is gelatinous in texture. The whole length of the left-hand side of the body is attached to the substrate. The body has a large dorsal tubercle with a horse-shoe shaped opening, and two inconspicuous siphons; a terminal inhalant oral siphon and a longer, exhalant atrial siphon that is positioned approximately two-thirds of the body length from the oral siphon. The oral siphon is surrounded by six to eight red , rounded lobes, whereas the atrial siphon is surrounded by six of the same. The inner surface of the oral siphon bears a ring of tentacles, and is linked to a large branchial cavity. The branchial cavity is perforated with rows of stigmata and bears small, irregular papillae on the right face of its dorsal lamina. The whole body is encased by a thin, translucent, cartilaginous test that has a smooth outer surface with small, rough projections and particles of shell attached.

Recorded distribution in Britain and Ireland

Ascidia conchilega is widespread on all coasts of Britain and Ireland.

Global distribution

Ascidia conchilega is widely distributed in north-west Europe, from the Faroes and west Norway to the mediterranean.

Habitat

Ascidia conchilega is found from low water to depths of at least 1000 m. This species attaches to hard substrate, such as stones and shells, as well as the holdfasts of various algae. It also inhabits the underside of rocks in tidepools.

Depth range

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Identifying features

  • Solitary sea squirt with elongate, oval-shaped body.
  • Body up to 6 cm in length.
  • Body attached to the substrate along entire length of left side.
  • Test is thin, translucent and smooth with small rough projections.
  • Greenish in colour with red spots on siphonic lobes.
  • Atrial siphon positioned two-thirds of body length from oral siphon.

Additional information

Ascidia conchilega is a filter-feeder. Individuals of this species are hermaphroditic and reproduce by externally fertilized eggs throughout January to December. Tadpole larvae, approximately 0.1 cm long, hatch from the eggs and settle on the substratum before metamorphosing into the adult form. This species is similar to Ascidia mentula which is larger, has a smooth surface and a grey to pink coloured, thick test.

Listed by

- none -

Further information sources

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Bibliography

  1. Costello, M.J., Bouchet, P., Boxshall, G., Emblow, C. & Vanden Berghe, E., 2004. European Register of Marine Species [On-line]. http://www.marbef.org/data/erms.php,

  2. Crothers, J. A., 1997. A key to the major groups of British marine invertebrates. Field Studies, 9, 1-177.

  3. Crothers, J.H. (ed.), 1966. Dale Fort Marine Fauna. London: Field Studies Council.

  4. Fish, J.D. & Fish, S., 1996. A student's guide to the seashore. Cambridge: Cambridge University Press.

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

  8. 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.]

  9. Laverack, M.S. & Blackler, D.M., 1974. Fauna & Flora of St. Andrews Bay. Scottish Academic Press (Edinburgh & London).

  10. MBA (Marine Biological Association), 1957. Plymouth Marine Fauna. Plymouth: Marine Biological Association of the United Kingdom.

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

  12. National Biodiversity Network (NBN) Atlas website. Available from: http://www.nbnatlas.org.  Accessed 01 April 2017

  13. 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., http://www.itsligo.ie/biomar/

Citation

This review can be cited as:

Richards, S. 2008. Ascidia conchilega A 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. Available from: http://www.marlin.ac.uk/species/detail/38

Last Updated: 03/07/2008