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

A red seaweed (Vertebrata lanosa)

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



A small reddish-brown filamentous alga most commonly associated with the fucoid alga Ascophyllum nodosum. The filaments are made up of a ring of 12 -24 elongated cells or siphons surrounding a central siphon. The plant is found wherever the host is common. Polysiphonia lanosa has occasionally been recorded as an epiphyte on Fucus serratus and Fucus vesiculosus and, more rarely, on rocky substrata.

Recorded distribution in Britain and Ireland

Found associated with Ascophyllum nodosum on suitable substrata on all coasts of Britain and Ireland.

Global distribution



Lives as epiphyte of Ascophyllum nodosum and more rarely on other fucoids. Common on the mid-littoral of rocky shores, but not extending far into estuaries.

Depth range


Identifying features

  • Reddish brown filamentous alga.
  • An epiphyte of Ascophyllum nodosum, on which they look like 'pom poms'.

Additional information

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Listed by

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Further information sources

Search on:


  1. Dickinson, C.I., 1963. British seaweeds. London & Frome: Butler & Tanner Ltd.

  2. Hardy, F.G. & Guiry, M.D., 2003. A check-list and atlas of the seaweeds of Britain and Ireland. London: British Phycological Society

  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]

  5. National Biodiversity Network (NBN) Atlas website. Available from:  Accessed 01 April 2017


This review can be cited as:

Pizzolla, P.F 2008. Vertebrata lanosa A red seaweed. 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. [cited 25-09-2018]. Available from:

Last Updated: 29/05/2008