A sea slug (Cadlina laevis)

NBN Interactive17-04-2008

Map accurate at time of writing. Visit NBN or OBIS to view current distribution

Researched bySonia Rowley Refereed byAdmin
Authority(Linnaeus, 1767)
Other common names- Synonyms-

Summary

Description

Cadlina laevis has a flattened, fragile oval body up to 3.2 cm in length. It is translucent white with opaque white or lemon-yellow pigmentation around the mantle edge. This species has distinctive white or lemon-yellow glands towards the mantle margin. The upper surface bears small conical, opaque white tubercules The underside is covered in a tracery of fine white markings. The front part of the foot (propodium) is groved to form two lips (bilaminate). Its white lamellate rhinophores are short and tapered, often with a yellow tip. The oral tentacles are short, broad and flattened. This species usually has 5 (rarely 6 or 7) tripinnate gills.

Recorded distribution in Britain and Ireland

This species is frequently recorded around most coasts of the British Isles.

Global distribution

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Habitat

Cadlina laevis is common among Lithothamnion covered rocks from the shore to the sublittoral. It can be found primarily on its prey, the sponges Halisarca dujardini and Dysidea fragilis.

Depth range

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Identifying features

  • Flattened oval body up to 3.2 cm in length.
  • Body, translucent white.
  • Opaque white or lemon-yellow pigmented mantle edge and glands.
  • Upper surface covered in small, conical, opaque tubercules.
  • The rhinophores are lamellate often with a yellow tip.
  • The oral tentacles are short, broad and flattened.

Additional information

Cadlina laevis was the first British nudibranch noted to reproduce by direct development (Thompson, 1967). Thompson (1967) observed that the embryonic period lasted for ca. 50 days with a vestigial veliger phase of 7 days occurring within the eggs. Tiny adults emerged from the eggs and remained benthic, having sufficient food reserves to sustain life and apparent growth for over a week before active feeding commenced (Thompson, 1967). Cadlina laevis feeds on encrusting sponges primarily Halisarca dujardiniand Dysidea fragilis. Interestingly, individuals of this species found in the north of the British Isles tend to have a milky white pigmentation and are mainly found in the littoral feeding on Halisarca dujardini. Individuals in the south and western parts of the British Isles have the distinctive lemon-yellow pigmentation and are mainly found feeding in the sublittoral on Dysidea fragilis (Picton & Morrow, 1994; Picton, 2001). It has been suggested that these two distinctive colour morphs may be separate species but the variation may be clinal due to its reproductive strategy (Picton & Morrow, 1994).

This species spawns in March and its penis is armed with numerous tiny hooked chitinous spines. The tripinnate gills of this species retract simultaneously into a common branchial pit, a process known as cryptobranchiate (Thompson, 1988).

Listed by

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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. Foster-Smith, J. (ed.), 2000. The marine fauna and flora of the Cullercoats District. Marine species records for the North East Coast of England. Sunderland: Penshaw Press, for the Dove Marine Laboratory, University of Newcastle upon Tyne.

  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. (ed.), 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. 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 http://www.marlin.ac.uk,

  6. Moen, F.E. & Svensen, E., 2004. Marine Fish & Invertebrates of Northern Europe. Southend-on-Sea: Aqua Press.

  7. NBN (National Biodiversity Network), 2002. National Biodiversity Network gateway. http://www.searchnbn.net, 2008-10-31

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

  9. 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/

  10. Picton, B.E., 2001. Cadlina laevis [on-line]. http://www.seaslugforum.net/, 2007-02-15

  11. Seaward, D.R., 1990. Distribution of marine molluscs of north west Europe. Peterborough: Nature Conservancy Council.

  12. Thompson, T.E., 1967. Direct development in a nudibranch, Cadlina laevis, with a discussion of developmental processes in Opisthobranchia. Journal of the Marine Biological Association of the United Kingdom, 47(1), 1-22.

  13. Thompson, T.E., 1988. Molluscs: Benthic Opisthobranchs. London: Bath Press. [Synopses of the British Fauna New Series), (ed. Doris M. Kermack & R.S.K. Barnes), no. 8 (second Edition)].

Citation

This review can be cited as:

Rowley, S.J. 2008. Cadlina laevis 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. Available from: http://www.marlin.ac.uk/species/detail/1

Last Updated: 17/04/2008