The beadlet anemone is the most familiar sea anemone in Britain. When disturbed or exposed to air at low tide it appears as a bright red blob of jelly (3), but when feeding up to 192 beautiful stinging tentacles emerge, arranged in 6 circles around the mouth. The smooth ‘body’ of the anemone, correctly known as the column, is usually bright red but may be greenish or brown, with blue, green or yellow spots. There is often a brilliant blue line around the adhesive base, and bright blue spots (known as acrorhagi) containing stinging cells are located at the top of the column (2).
The beadlet anemone is extremely well-adapted to life on the shore, and is able to withstand desiccation and fluctuations in temperature (2). Prey is caught with the stinging tentacles and passed to the mouth (3). Although often thought of as sessile animals, they are able to move by sliding the base along the substratum. They have even been shown to slowly move away from predators such as sea-slugs when facing attack (2). Amazingly, they are even aggressive to neighbouring beadlet anemones. When the tentacles of two adjacent anemones come into contact, one will sting the other, leading to the other individual being forced to move away (1).
Beadlet anemones are either male or female, but it is not yet understood if sexual reproduction occurs. Both sexes are known to brood offspring internally before giving birth to live young. It is thought that the offspring are produced asexually by a process of internal ‘budding’. However, some experts believe that sexual reproduction leading to pelagiclarvae may take place in some situations (2).
Ager, O.E.D. (2001) Actinia equina. Beadlet anemone Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme. [On-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 27/11/2003]. Available on-line at: http://www.marlin.ac.uk/species/Actiniaequina.htm
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.
Slightly salty water.
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.
Ager, O.E.D. (2001) Actinia equina. Beadlet anemone 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/Actiniaequina.htm
Fish, J.D. and Fish, S. (1989) A student’s guide to the seashore. Unwin Hyman Ltd., London.
Buczaki, S. (2002) Fauna Britannica. Hamlyn, London.
Gibson, R., Hextall, B. and Rogers, A. (2001) Photographic Guide to the Sea & Shore Life of Britain and North-west Europe. Oxford University Press, Oxford.
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