Description

A.equina is the most commonly seen anemone around the Essex coast. The column is smooth and usually deep red but a green form is also quite common. Around the base of the column there can usually be seen a thin blue line and the basal disc can measure up to 50mm in diameter. The tentacles are fully retractable and up to 200 in number, arranged in six circles. There is a conspicuous ring of blue spots, called acrorhagi, around the top margin of the column. These acrorhagi increase in number as the anemone grows larger.

Widely distributed and very common on rocky shores throughout north-west Europe. Found around the Essex coast were it uses artificial structures such as breakwaters and other hard hard substrates such as boulders to fix to. It is highly adapted to life in the intertidal zone and can be found from HWN down to a depth of 10-20m. Adaptations relate to the toleration of high temperatures and to dessication.

Intra-specific aggression has been recorded between neighbouring individuals. During the encounter there is tentacle contact, and discharge of nematocysts from the acrorhagi, until one of the individuals moves away. There is evidence that there is a hierarchy of aggression which is based on size. This behaviour is possible related to the spacing out of individuals on the shore.

A.equina has relatively short tentacles which prevent it from searching actively for prey so is considered as an opportunistic omnivorous suspension feeder. There are three basic ways of macro-feeding in A.equina a) Prey floating in the water column, mostly zooplankton, is intercepted by one or more tentacles and transferred to the mouth, b) Sessile prey that may have been dislodged by strong wave action or during the the foraging activities of a predator is washed into the tentacle crown, c) Motile prey, such as small sea urchins, crustaceans or fish may accidentally become entangled in the anemones tentacles. This last method is more probable to happen in turbid waters where the potential prey cannot see the anemone until it is too late or in turbulent waters where the prey cannot prevent itself from being washed into the anemones tentacles. It has also been found that organic detritus is an important food source for A.equina.

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References:

Brace R.C & Pavey J, 1978, Size-dependent dominance heirarchy in the anemone Actinia equina, Nature 273, 752-753.

Chintiroglou C & Koukouras A, 1992, The feeding habits of three Mediterranean sea anemone species, Anemonia viridis (Forskål), Actinia equina (Linnaeus) and Cereus pedunculatus (Pennant) Helgoland Marine Research 46, 53-68.

Fish J.D & Fish S ,1996, A Student's Guide to the Seashore.

Hayward P, Nelson-Smith T & Shields C, 1996, Collins pocket guide, Seashore of Britain & Europe.

Hayward P.J & Ryland J.S, 2006, Handbook of the Marine Fauna of North-West Europe.

Moen F.E & Svenson E, 2004, Marine Fish and Invertebrates of Northern Europe.