MarLIN

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

A spoon worm (Thalassema thalassemum)

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

Summary

Description

Thalassema thalassemum is an unsegmented, soft-bodied spoon worm. The main body, or trunk, is bilaterally symmetrical and reaches a length of up to 2-7 cm. The colour of the trunk varies between individuals and may be blue, grey, yellow, pink or purple. On the surface of the trunk are numerous papillae that are arranged in rings around the body, and which increase in number towards the posterior. Along the middle of the ventral surface of the body there is sometimes a single white line. The mouth is positioned at the base of the proboscis and behind this lies a pair of chaetae. The proboscis is coloured peach or cream, can extend up to 10-20 cm and may appear to have a ventral channel when its lateral margins roll inwards during feeding.

Recorded distribution in Britain and Ireland

Thalassema thalassemum is recorded from south-west England, south-west Wales, southern and western Ireland and south-west Scotland. In addition, it has been recorded at Strangford Lough, Northern Ireland, Isle of Man and off north Wales.

Global distribution

Thalassema thalassemum has been found in the Mediterranean, Japan, Louisiana, Sierre Leone and France.

Habitat

Thalassema thalassemum inhabits sandy or muddy sediments and rock crevices at both low and shallow water. It creates a u-shaped burrow within the sediment that is lined with mucus.

Depth range

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Identifying features

  • Soft, plump, bilaterally symmetrical, cylindrical body of up to 2-7 cm.
  • Proboscis of up to 10-20 cm.
  • Mouth at base of proboscis.
  • One pair of hooked chaetae located behind mouth.
  • Numerous wart-like papillae arranged in rings.
  • Colour of body blue, grey, yellow, pink or purple.
  • Colour of proboscis peach or cream.
  • End of proboscis either round or pointed.

Additional information

Thalassema thalassemum is the smallest of the Echiurans. Its main body is capable of contracting to 2-3 cm. It is a deposit feeder, using its proboscis to secrete a mucus sheet that traps detritus. Thalassema thalassemum is gonochoristic, although there is no sexual dimorphism, and reproduces by external fertilization in the summer. A free-swimming planktonic larva stage develops from fertilized eggs before developing into the adult form. Thalassema thalassemum is mainly nocturnal.

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

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

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

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

  6. 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.]

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

  8. Nickell, L.A. & Atkinson, R.J.A., 1994. Observations on the behaviour of Thalassema thalassemum (Echiura: Echiuridae). Journal of the Marine Biological Association of the United Kingdom, 74(4), 963-966,

  9. Wilkie, I.C 1990. First record of the spoon-worm Thalassema thalassemum (Pallas), Echiura, in Scottish waters. Glasgow Naturalist, 21, 515-517,

Citation

This review can be cited as:

Richards, S. 2009. Thalassema thalassemum A spoon worm. 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/17

Last Updated: 03/07/2009