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Seaweek 2010: Oceans of Life - ours to explore; ours to restore


• Sea anemones are a group of water dwelling, predatory animals of the order Actiniaria.They resemble a very large single coral polyp without a skeleton.

• Sea anemones are cylindrical with a ring of tentacles that surround the mouth. The bottom of the anemone is attached by a special disc but is capable of moving around by sliding very slowly over rocks and dead coral. Some anemones can get quite large (almost 1 m across). Sea anemones can be brightly coloured but may also be quite drab in other species. This type of colouration is a type of camouflage which may be important in reducing the extent to which anemones are able to be spotted by potential prey.

• Anemones are found in all oceans, from the intertidal region (e.g. rock pools) and in the dark depths of the ocean. They are generally attached, but will move slowly around the bottom of the sea, it can take a week to move one centimetre!

• Although they have a reputation as fish eaters, many sea anemones are scavengers and will eat both plant and animal matter. They are also famous for the symbiotic relationships they form with fish, crabs and other organisms.

• Some anemones are predatory. Predatory anemones have powerful stinging tentacles that catch a range of animals including fish, prawns and other small animals. The stinging tentacles of anemones are due to the presence of tiny barb-like organelles called nematocycts that fire out of cells called cnidocytes like little harpoons. These little harpoons are often have poison in their tips that can paralyse their prey with seconds.

• Fish are probably the most significant predator of the anemone, especially puffer fish, butterfly fish and parrot fish. Their soft tissues are ideal food for these animals. Fortunately, the fact that anemones have the same powerful stinging cells that allow them to hunt other animals is a good deterrent.

• Sea anemones have a swimming larval stage called a planula. They are only a millimeter long and swim around for 4-20 days before deciding where to settle.

• Sea anemones are generally not dangerous to humans. Normally human skin is too thick for the anemone’s stinging cells to get through. Anemones are generally not eaten by humans. However, recent increases in the number of anemones and their anemone fish being caught for home aquariums are making anemones become rare in many tropical oceans. There is a great need for this trade in anemones to be controlled. Many countries in the world are starting to introduce yearly quota (i.e. a limit on the number taken in any one year) to ensure that they do not become extinct.

Interesting Fact; Anemones can do an amazing thing – they can clone themselves! It involves tiny bits of the mother or father anemone splitting of and becoming a baby anemone. Because the baby anemone is exactly the same as the mother or father, they are actually the same individual. This means that anemones may live forever and ever and ever!

Further links;

• Reef Education:

• Wikipedia:

• ReefEd:




Sea anemone from GBRMPA Image Collection

Sea anemone from GBRMPA Image Collection


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