Beadlet anemone

Beadlet anemone
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Cnidaria
Class:	Hexacorallia
Order:	Actiniaria
Family:	Actiniidae
Genus:	Actinia
Species:	A. equina
Binomial name
Actinia equina (Linnaeus, 1758)

A colony of beadlet anemones(Rogaland, Norway)

The beadlet anemone (Actinia equina) is a common sea anemone found on rocky shores around all coasts of the British Isles. Its range extends to the rest of Western Europe and the Mediterranean Sea, and along the Atlantic coast of Africa as far south as South Africa.

Actinia equina can be found both in exposed and sheltered situations. It is highly adapted to the intertidal zone as it can tolerate both high temperatures and desiccation. The anemone may also be found in regions of variable salinity such as estuaries.

Underwater, it displays up to 192 tentacles, arranged in six circles. Out of water, the tentacles retract and the anemone resembles a blob of red, brown, green or orange jelly, up to about 5 centimetres (2.0 in) across. It has bright blue beads (known as acrorhagi) located just beneath the tentacles, organised as an external ring containing stinging cells located at the top of the column that it uses to fight over territory. The acrorhagi contains the cnidocysts which themselves contain the nematocysts. There is some evidence that the various colour forms may in fact be different species.

Actinia equina is similar in form to the Waratah anemone (Actinia tenebrosa) of Australia and New Zealand. It is also similar in form to the strawberry anemone (Actinia fragacea) but is a uniform colour and is typically rather smaller.

Actinia equina is viviparous, with up to one hundred embryos developing inside the body cavity before being ejected into the open water as juveniles.

References

• Naylor, P, Great British Marine Animals, 2nd edn, Sound Diving Publications, 2003.
• Marine Life Information Network (MarLIN)
• Encyclopedia of Marine Life of Britain and Ireland
• WoRMS (2011). "Actinia equina (Linnaeus, 1758)". World Register of Marine Species.

External links

• Photos of Beadlet anemone on Sealife Collection