Starlet sea anemone (Nematostella vectensis)

Starlet sea anemone, showing oral disk surrounded by two rings of tentacles
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Starlet sea anemone fact file

Starlet sea anemone description

GenusNematostella (1)

This greyish-white anemone has a bulbous central section with a contracting column that enables it to burrow into soft mud. At the top of the column is an oral disk that contains the mouth and is surrounded by two rings of tentacles, totalling 16 to 20 (4).

Tentacle length: 15 mm (2)
Tentacle diameter: 1 mm (2)

Starlet sea anemone biology

Sea anemones are largely sedentary, moving occasionally by creeping extremely slowly or by inflating slightly and allowing currents to move them. The starlet sea anemone pushes its lower half into the mud and contracts its column to burrow into the fine mud, securing itself against water currents. They feed by holding out their tentacles to catch passing food particles and transferring them to the mouth. The starlet sea anemone is not selective in its feeding habits, consuming mainly copepods and midge larvae (4).

It reproduces asexually year-round, dividing in half and re-growing each half. During summer and autumn, when resources are plentiful and the water quality is good, the starlet sea anemone will reproduce sexually, with simultaneous release of masses of gelatinous eggs by females and free-swimming sperm by males. There are several larval stages, ultimately metamorphosing into a tiny juvenile with just four tentacles after seven days. The juveniles become reproductively mature after 69 days (5).


Starlet sea anemone range

The starlet sea anemone is found on the east and west coasts of the United States, in Nova Scotia, Canada, and in the coastal lagoons of the Isle of Wight, Sussex, Hampshire, Dorset and East Anglia in the UK (3) (4).

You can view distribution information for this species at the National Biodiversity Network Atlas.

Starlet sea anemone habitat


Starlet sea anemone status

The starlet sea anemone is classified as Vulnerable (VU A1ce) on the IUCN Red List 2004 (1) and as Rare in the Red Data Book of Great Britain (3). It is also listed under Schedule 5 of the UK Wildlife and Countryside Act 1981 (3).

IUCN Red List species status – Vulnerable


Starlet sea anemone threats

Whilst populations are stable in the US and Canada, UK populations are small, patchy and at risk (4). British coastal habitats are being damaged by pollution, drainage and in-filling. Isolation of coastal pools can lead to isolation of populations and potential inbreeding depression. Coastal defence works are also responsible for the loss of some sea anemone habitat (3).


Starlet sea anemone conservation

Saline lagoons are a priority under the EC Habitats Directive, and the starlet sea anemone is protected under the Wildlife and Countryside Act. It has a Species Action Plan that proposes the maintenance of all viable populations at all known sites, as well as surveys to document the entire UK range of the species. It is also suggested that the starlet sea anemone be reintroduced to three sites during 2005 (3).

View information on this species at the UNEP World Conservation Monitoring Centre.
There may be further information about this species available via the National Biodiversity Network Atlas.
The UK Biodiversity Action Plan for this species is available at UK BAP.

Find out more

For further information on this species see UK BAP website:



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:


Of asexual reproduction: reproduction that does not involve the formation of sex cells (‘gametes’). In many species, asexual reproduction can occur by fission (or in plants ‘vegetative reproduction’); part of the organism breaks away and develops into a separate individual. Some animals, including vertebrates can develop from unfertilised eggs, this process - known as parthenogenesis - gives rise to offspring that are genetically identical to the parent.
Large and diverse group of minute marine and freshwater crustaceans belonging to the subclass Copepoda. They usually have an elongated body and a forked tail.
Inbreeding depression
The reduction in viability, birth weight, and fertility that occurs in a population after one or more generations of inbreeding (interbreeding amongst close relatives).
Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
Of the stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
An abrupt physical change from the larval to the adult form.


  1. IUCN Red List (February, 2005)
  2. Encyclopedia of Marine Life of Britain and Ireland (February, 2005)
  3. UK BAP (February, 2005)
  4. Animal Diversity Web (February, 2005)
  5. Uhlinger, K.R. and Hand, C. (1992) The culture, sexual and asexual reproduction and growth of the sea anemone Nematostella vectensis. Biological Bulletin, 182(2): 169 - 176.

Image credit

Starlet sea anemone, showing oral disk surrounded by two rings of tentacles  
Starlet sea anemone, showing oral disk surrounded by two rings of tentacles

© SERTC, South Carolina Department of Natural Resources

Southeastern Regional Taxonomic Center (SERTC)
Marine Resources Research Institute
PO Box 12559
SC 29422
United States of America
Tel: 843-953-9098


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