Magnificent Sea Anemone

The magnificent sea anemone, also called the Ritteri anemone, is a large sea anemone of Indo-Pacific reefs. It is best known as a home for anemonefish, and it is one of the most generous hosts on the reef. It feeds in two ways at once, and it can be a striking splash of colour on an open, sunlit rock. It has not been assessed by the IUCN.

Also known as: magnificent giant anemone, Heteractis magnifica

Do not use the tentacles, which look much like those of other big host anemones. Look at the base instead: the column below the tentacle crown is a solid, vivid colour, while the oral disc and the tentacle bases are pale beige to white. That contrast between a bright column and a pale disc is the mark. The finger-like, often pale tentacle tips help confirm it.

The animal is a wide, flared oral disc, the flat upper surface with the mouth in the middle, carrying many long tentacles. The disc, the bases of the tentacles and the mouth are all the same colour, from light beige to white. The tentacle tips are finger-shaped and are often paler than the rest of the tentacle, and sometimes brightly coloured. The real colour is in the column, the outer body wall, which shows when the animal pulls its tentacles in. It can be electric blue, green, red, pink, purple or brown, and this bright column is what the name refers to.

This anemone is widespread in tropical and subtropical waters of the Indo-Pacific, from the East African coast and the Red Sea to Polynesia, and from southern Japan to Australia and New Caledonia. It sits on hard substrate in well-lit, current-swept spots, usually shallow. Across most of its range it lives as single animals; dense clusters appear only at the edges of the range.

It feeds in two ways. Tiny algae called zooxanthellae live inside its tissue and make food from sunlight, which is why it chooses bright, exposed places. It also uses its tentacles to sting and hold small prey such as small invertebrates and young fish. It can reproduce by releasing eggs and sperm into the water, or simply by splitting itself into two animals. Many kinds of anemonefish shelter in it, along with threespot dascyllus and several small shrimps.

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  Atlantic Beadlet Anemone

  Actinia equina

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  Daisy Anemone

  Cereus pedunculatus

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  Gem Anemone

  Bunodactis verrucosa

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  Giant Anemone

  Condylactis gigantea

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  Mediterranean Beadlet Anemone

  Actinia mediterranea

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  Snakelocks anemone

  Anemonia viridis