Red Sea Anemone

Red Sea Anemone, Red Waratah Anemone – All Photos – Anne Wietheger

You probably have seen this one before: the dark red blobs sitting above the water line during sitting above the water line during low tide on rocks around the rock pools on Wellington’s South Coast. And when the tide comes back in, the blobs are turning into elegant anemones with their bright red tentacles waving in the water.

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Red Sea Anemone

This anemone is aptly called ‘Red Sea Anemone’, or ‘Red Waratah Anemone’; and its scientific name is Actinia tenebrosa and in maori, it is called kōtoretore.

The Red Sea Anemone is common around New Zealand and its offshore islands, including the Kermadec and the Auckland Islands. It also occurs in Australia and its offshore islands south of the Tropic of Capricorn.

This anemone lives in the intertidal and can be found up to the high-tide mark. Clusters are found occupying crevices and pools on most rocky shores, mainly under shaded ledges, in caves and under stones.

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Red Anemone out of water

The Red Sea Anemone has a deep red body column, a light red central oral disc and bright red tentacles. The smooth body column is 30 – 40 mm in length when expanded. Numbers of tentacles can total 150 – 200 in large specimen and are up to 15 mm in size.

Characteristic for the genus Actinia, to which the Red Sea Anemone belongs, are 24 light cobalt blue beads (acrorhagi), which are arranged in a circle at the base of the tentacle crown. These contain stinging cells, or nematocysts, and are used in defence interactions, e.g. to compete for space.

The Red Sea Anemone is viviparous. The young anemones are brooded within the gastric column of the parental polyp, which can be female as well as male. Fully formed young polyps are released through the mouth by contraction of the body wall.

These anemones are often found in clusters because the offspring settles close to the parental polyp.

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Red Anemone
Resources

De C. Cook, S. (Editor) 2010. New Zealand Coastal Marine Invertebrates 1. Canterbury University press

Wing, S. 2008. Subtidal invertebrates of New Zealand- A divers’ guide. Canterbury University press

Dell, R.K. 1981. Seashore Life- Mobil New Zealand Nature Series. Heinemann Reed

Leslie, M.A. 1968. Animals of the rocky shore of New Zealand. A.H. & A.W. Reed