Biodiversity & Conservation

Thongweed - Himanthalia elongata

Himanthalia elongata

Image Paul Newland - Stand of Himanthalia elongata at Outer Hope. Image width ca XX cm.
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Distribution map

Himanthalia elongata recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

Why do the maps differ?

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Himanthalia elongata is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Ochrophyta Brown and yellow-green seaweeds
Class Phaeophyceae
Authority (Linnaeus) S.F.Gray, 1821
Recent synonyms None
Map icon Recorded Distribution in Britain and Ireland All coasts of Britain and Ireland, except south east England.
Habitat information icon Habitat information Himanthalia elongata is found attached to hard substrata on moderately exposed shores. It is found at the bottom of the shore, where it forms a band below Fucus serratus and above laminarians.
Text page icon Description A common brown seaweed, which has a two stage morphology. Small button-like thalli are first produced, from which long strap-like reproductive fronds (receptacles) are formed in autumn. The strap-like reproductive fronds grow quickly between February and May, reaching a length of up to 2 m. The plant releases gametes from June until the winter when it starts to decay. Plants commonly live for 2-3 years and reproduce once before dying.
Identifying features
  • Thallus is button-like with a short stipe and is up to 3 cm in diameter.
  • Strap-like reproductive bodies are produced from the centre of the button, which are dichotomously branched.
  • Up to 2 meters in length.
Additional information icon Additional information Also commonly known as sea thong.

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This review can be cited as follows:

Nicola White 2008. Himanthalia elongata. Thongweed. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 09/02/2010]. Available from: <http://www.marlin.ac.uk/speciesinformation.php?speciesID=3491>