MarLIN

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

A horseshoe worm (Phoronis muelleri)

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

Summary

Description

The horseshoe worm Phoronis muelleri is elongated and worm- shaped. The mouth is surrounded by a characteristic horseshoe shaped arangement of tentacles known as the lophophore. Phoronis muelleri can be up to 12 cm in length but less than 1 mm in width. The body is a pinkish colour and the lophophore is transparent, sometimes with spots. The lophophore of Phoronis muelleri sometimes has medially turned ends and the numerous tentacles are notably shorter near the mouth but may reach up to 2 mm in length.

Recorded distribution in Britain and Ireland

Found all around British coasts and has been recorded off the north-east coast of Ireland.

Global distribution

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Habitat

Phoronis muelleri penetrates vertically into muddy to sandy substrates, often with a high organic content and with an abundance of detritus and suspended material. It can be found from the intertidal zone to a depth of up to 400 m. It is frequently recorded in Macoma and Amphiura communities. Phoronis muelleri occurs in either boring or encrusting forms and may secrete and live in a membranous, cylindrical tube.

Depth range

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Identifying features

  • Up to 12 cm in length, 1 mm in width.
  • Horseshoe shaped lophophore with short tentacles less than 2 mm in length.
  • Tentacles shorten towards the mouth.
  • No inward fold at the base of the lophophore.
  • The nephridia (kidney-like organ) has only one funnel.
  • Only one giant nerve fiber is present.

Additional information

Phoronida have a characteristic ciliated and free-swimming pelagic larva, known as Actinotrocha. Separate names for larval and adult forms may still be used in taxonomy (Emig, 1979).

Listed by

- none -

Further information sources

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Bibliography

  1. Emig C.C., Çinar M.E. & Ergen, Z., 2003. Phoronida from the Eastern Mediterranean and Black Sea. Cahiers de Biologie Marine, 44, 185-190.

  2. Emig, C.C., 1979. British and other phoronids. London, Academic Press

  3. 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.]

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

  5. OBIS,  2017. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2017-11-24

Citation

This review can be cited as:

Barnes, M.K.S. 2008. Phoronis muelleri A horseshoe 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/95

Last Updated: 03/04/2008