A catworm (Nephtys incisa)

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



Nephtys incisa has a body measuring from 2.5-6.5 cm in length, divided into between 60 and 70 segments. When viewed in cross-section, the body appears rectangular. It has a prominent proboscis (feeding end of digestive tract) with numerous but very small papillae, except the mid-dorsal papilla, which is very large.

Recorded distribution in Britain and Ireland

See additional information.

Global distribution

Recorded from off north west Africa, in the Mediterranean, the north east Atlantic including the North Sea, Skagerrak and Kattegat, and as far north as Greenland.


Nephtys incisa occurs in sediments ranging from gravel and mud to soft silt, but most commonly in silty sand or mud substrata. It can be found from shallow to deep water.

Depth range


Identifying features

  • Body with 60-70 segments, from 2.5 -6.5 cm long, and is rectangular in cross-section.
  • Numerous papillae on proboscis, one of which is very large (mid-dorsal).
  • The chaetae (bristles) in the posterior parapods (lateral appendages of the trunk segments) are finely toothed, and none are sharply bent.
  • The dorsal branch of the parapodium (notopod) is very well separated from the ventral branch of parapodium (neuropod).

Additional information

Once the genus has been identified, it is not too difficult to identify individual species. However, mistakes can easily be made due to varying body length, and comparisons should be made on distinct fractions of the bodies (see Fauchald, 1977 for details).

Listed by

- none -


  1. Fauchald, K., 1977. The polychaete worms. Definitions and keys to the orders, families and genera. USA: Natural History Museum of Los Angeles County.

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

  5. Rainer, S.F., 1990. The genus Nephtys (Polychaeta: Phyllodocida) of northern Europe: redescription of N. hystricis and N. incisa. Journal of Natural History, 24, 361-372.


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

  2. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2024-03-02


This review can be cited as:

Mayhew, E.M. 2005. Nephtys incisa A catworm. 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 02-03-2024]. Available from: https://www.marlin.ac.uk/species/detail/1821

Last Updated: 26/10/2005