Sea tamarisk (Tamarisca tamarisca)

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



A colonial hydroid that grows up to 15 cm or more. It is straggly in appearance with alternate branches, widely spaced along the stem. The hydrothecae, a supporting, nonliving, protein-chitinous envelope surrounding the stem, is large, up to 1.6 mm long, tubular and variously outward curving. It is easily mistaken for a sparsely branched form of Abietinaria abietina but is distinguished by opposite hydrothecae.

Recorded distribution in Britain and Ireland

All British and Irish coasts.

Global distribution



A circalittoral species normally found in moderate to strong tidal streams attached to bedrock or stable rocks or shells.

Depth range


Identifying features

  • Colony 15 cm or more, straggly; monosiphonic throughout; branches alternate, widely spaced.
  • Male gonotheca kite-shaped, flattened, tapering to short pedicel below.
  • Female gonotheca conical, distal end hidden by two large, ragged flaps cut into several fingers.

Additional information

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

  2. 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.]


  1. NBN (National Biodiversity Network) Atlas. Available from:

  2. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2024-06-20


This review can be cited as:

Wilson, E. 2002. Tamarisca tamarisca Sea tamarisk. 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 20-06-2024]. Available from:

Last Updated: 17/07/2002