A fanworm (Ficopomatus enigmaticus)

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



Ficopomatus enigmaticus is a fan-worm that forms thin, white, calcareous tubes that turn yellowish-brown with age and are up to 8 cm in length and 0.1-0.2 cm in diameter. Tubes are marked by fine, transverse rings that spread outwards, reflecting previous growth. Thousands of individuals grow together at an individul rate of up to 2 cm per month to form huge reefs up to 50 cm in height and 4 m across, varying in shape from circular to elongate depending on water flow. The worm's body consists of a head, a seven segmented thorax, a 50-120 segmented abdomen and a tail segment. It grows to up to 2.5 cm in length and is greenish or reddish-orange in colour. The head has paired lobes, each bearing green, darkly banded, feather-like feeding tentacles up to 0.3 cm long and arranged in a semi-circle. One or more of the tentacles are modified into a yellowish-brown, fig-shaped operculum with dark spines. The base of the head is surrounded by a tall, faintly ribbed collar. The segments of the thorax, except for the first, are marked by a dorsal faecal groove and bear bundles of chaetae in two rows. The segments of the abdomen, except for the first to third, bear bundles of two to five chaetae also in two rows. The pygidium bears two small lateral lobes.

Recorded distribution in Britain and Ireland

Found at several locations around the British Isles, including north-east, south-west and north-west England, south-west Wales and off the coasts of County Galway, Ireland.

Global distribution

Ficopomatus enigmaticus is a southern species present in the mediterranean, south Africa, Argentina, New Zealand and Australia from where it may have originated.


Ficopomatus enigmaticus inhabits warm shallow sublittoral waters as well as brackish estuaries, docks and lagoons. This species forms reefs on different types of hard substrate including rocks and solid surfaces such as hulls of ships and pipes.

Depth range


Identifying features

  • Greenish or reddish-orange bodied tube-building fan worm.
  • Body up to 2.5 cm in length and divided into 7 thoracic segments and up to 50-120 abdominal segments
  • Most segments bear bundles of chaetae.
  • Head with paired lobes, each bearing green, darkly banded feather-like tentacles.
  • Operculum yellowish-brown, fig-shaped with dark, inwardly curved, chitinous spines.

Additional information

Ficopomatus enigmaticus is a suspension-feeder. It has a planktonic larvae and reproduces by external fertilization. This species lacks true gonads and, although generally gonochoristic, hermaphroditism has been recorded in some populations.

Listed by

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  11. Obenat, S., Spivak, E., & Orensanz, J.M., 2006. Reproductive biology of the invasive reef-forming serpulid, Ficopomatus enigmaticus, in the Mar Chiquita coastal lagoon, Argentina. Invertebrate Reproduction and Development, 49(4), 263-271,

  12. Read, G.B. & Gordon, D.P. 1991. Adventive occurrence of the fouling serpulid Ficopomatus enigmaticus (Polychaeta) in New Zealand. New Zealand Journal of Marine and Freshwater Research, 25(3), 269-273.

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  1. Bristol Regional Environmental Records Centre, 2017. BRERC species records recorded over 15 years ago. Occurrence dataset: https://doi.org/10.15468/h1ln5p accessed via GBIF.org on 2018-09-25.

  2. Fenwick, 2018. Aphotomarine. Occurrence dataset http://www.aphotomarine.com/index.html Accessed via NBNAtlas.org on 2018-10-01

  3. Kent Wildlife Trust, 2018. Kent Wildlife Trust Shoresearch Intertidal Survey 2004 onwards. Occurrence dataset: https://www.kentwildlifetrust.org.uk/ accessed via NBNAtlas.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: 2024-06-12

  7. South East Wales Biodiversity Records Centre, 2018. INNS Data: All Taxa (South East Wales). Occurrence dataset: https://doi.org/10.15468/crhjs2 accessed via GBIF.org on 2018-10-02.

  8. 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.


This review can be cited as:

Richards, S. 2008. Ficopomatus enigmaticus A fanworm. 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 12-06-2024]. Available from: https://www.marlin.ac.uk/species/detail/19

Last Updated: 03/07/2008