A sludge-worm (Tubificoides benedii)

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



Tubificoides benedii is a slender worm that may grow up to 5.5 cm in length, with between 75-100 body segments. In Tubificoides benedii the body wall is thinly covered with cuticular folds (papillate) which give the worm a rough feel. The body segments have on each side an upper and lower bundle of chitinous bristles (setae), that are able to move and are used for burrowing. The worm may appear red in colour, owing to the possession of the respiratory pigment haemoglobin. Oligochaetes are hermaphrodites, with paired male and female sex organs opening separately on the underside.

Recorded distribution in Britain and Ireland

On all coasts of Britain, probably under recorded in Ireland.

Global distribution



Found in marine and brackish water cohesive muds.

Depth range


Identifying features

Reference to Brinkhurst (1982) and Brinkhurst & Jamieson (1971) is recommended.
  • Thin, segmented worm, up to 5.5 cm in length, that is red in colour.
  • Eyespots absent.
  • Body wall thinly but evenly covered with papillae.
  • Testes in body segment X and male pore in segment XI.
  • Ovaries in body segment XI and spermatheca (sac-shaped invagination of body wall for receiving sperm during copulation) in segment X.
  • All setae indistinctly bifid (double-pointed) with reduced upper points, or simple-pointed.
  • Penis sheaths cylindrical with recurved distal end.

Additional information

Oligochaetes are segmented, bilaterally symmetrical, cylindrical worms, with tapering ends. Typically each body segment possesses four bundles of setae (chitinous bristles projecting from the body). The setae vary considerably in size and shape, and between families, so are consequently used extensively in identification. Examination under a microscope and of internal anatomy is likely to be required for accurate identification (see Brinkhurst, 1982), and attention paid to the rather complex reproductive system. The number of gonads, the position of one gonad relative to the other, and the body segments in which they occur are used to define families. In the Tubificidae the form of the male duct is used to define genera.

Listed by

- none -


  1. Brinkhurst, R.O. & Jamieson, B.G.M., 1971. Aquatic Oligochaeta of the world. Edinburgh: Oliver & Boyd.

  2. Brinkhurst, R.O., 1982. British and other marine and estuarine oligochaetes. Cambridge University Press, [Synopses of the British Fauna, No. 21].

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

  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] http://www.jncc.gov.uk/mermaid


  1. Centre for Environmental Data and Recording, 2018. Ulster Museum Marine Surveys of Northern Ireland Coastal Waters. Occurrence dataset https://www.nmni.com/CEDaR/CEDaR-Centre-for-Environmental-Data-and-Recording.aspx accessed via NBNAtlas.org on 2018-09-25.

  2. Environmental Records Information Centre North East, 2018. ERIC NE Combined dataset to 2017. Occurrence dataset: http://www.ericnortheast.org.ukl accessed via NBNAtlas.org on 2018-09-38

  3. Merseyside BioBank., 2018. Merseyside BioBank (unverified). Occurrence dataset: https://doi.org/10.15468/iou2ld accessed via GBIF.org on 2018-10-01.

  4. National Trust, 2017. National Trust Species Records. Occurrence dataset: https://doi.org/10.15468/opc6g1 accessed via GBIF.org on 2018-10-01.

  5. NBN (National Biodiversity Network) Atlas. Available from: https://www.nbnatlas.org.

  6. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2024-07-21

  7. South East Wales Biodiversity Records Centre, 2018. SEWBReC Worms (South East Wales). Occurrence dataset: https://doi.org/10.15468/5vh0w8 accessed via GBIF.org on 2018-10-02.

  8. Suffolk Biodiversity Information Service., 2017. Suffolk Biodiversity Information Service (SBIS) Dataset. Occurrence dataset: https://doi.org/10.15468/ab4vwo accessed via GBIF.org on 2018-10-02.


This review can be cited as:

Budd, G.C. 2005. Tubificoides benedii A sludge-worm. In Tyler-Walters H. and Hiscock K. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 21-07-2024]. Available from: https://marlin.ac.uk/species/detail/1862

Last Updated: 27/10/2005