Enteromorpha (Enteromorpha spp.)

KingdomPlantae
PhylumChlorophyta
ClassUlvophyceae
OrderUlvales
FamilyUlvaceae
GenusEnteromorpha (1)
SizeLength: up to 700 mm (2)

Not threatened (2).

Species within the genus Enteromorpha are very difficult to identify as differences between species are small and hard to spot (3). They are green seaweeds, with tubular and elongate fronds that may be branched, flattened or inflated (2). They are bright green in colour and may occasionally be bleached white, particularly around rock pools (4). They attach to the substrate by means of a minute disc-like holdfast (4). The fronds of a species may vary in appearance due to changes in environmental conditions, which further confuses identification, and microscopic examination of cell details is often necessary to identify a species with certainty (3).

This genus is widespread in north-west Europe and has a wide global distribution with gutweed (E. intestinalis) having a global distribution (3). Enteromorpha compressa, E. intestinalis (gut weed) and E. linza are all common and widespread around the British coast (3).

These green seaweeds are found at all levels of the shore, and seem to particularly thrive in areas where freshwater run-offs occur (2). They are also found in estuaries and saltmarshes, and is able to withstand low salinities (2). Where conditions are calm the seaweed may detach and survive as free-floating clumps (2).

Species of Enteromorpha are summer annuals; they decay at the end of the season, producing masses of decaying bleached fronds (3). These seaweeds are fast-growing species that are able to reproduce quickly (3). The life cycle passes through a number of stages. The ‘gametophyte’ stage produces massive amounts of mobile sex cells or gametes that fuse together to form the ‘sporophyte’ stage. This stage then produces mobile spores, which develop into the gametophyte stage, and the cycle begins once more (3). The gametes and spores are produced in such massive quantities that the water becomes green. Their release is synchronised with the tidal cycles (3).

In some parts of the world gut weed (E. intestinalis) is sold as a foodstuff (4).

These species are not threatened.

Conservation action is not required for these species.

Budd, G.C. & Pizzola, P. (2002) Enteromorpha intestinalis. Gut weed. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. Available from:
http://www.marlin.ac.uk/species/Ulvaintestinalis.htm

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact: arkive@wildscreen.org.uk

  1. National Biodiversity Network Species Dictionary (January, 2004)
    http://www.nhm.ac.uk/nbn
  2. Fish, J.D. and Fish, S. (1989) A student’s guide to the seashore. Unwin Hyman Ltd, London.
  3. Budd, G.C. & Pizzola, P. (2002) Enteromorpha intestinalis. Gut weed. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. (November, 2003)
    http://www.marlin.ac.uk/species/Ulvaintestinalis.htm
  4. Gibson, R., Hextall, B. and Rogers, A. (2001) Photographic guide to the sea and shore life of Britain and north-west Europe. Oxford University Press, Oxford.