Those brave yellow defenders - the anemone fish

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By marine biologist, Daniele Zanoni

More and more people refer to these fish as Nemos. Others call them clown fish. The English common name of the ones we normally see in Sharm El Sheikh is anemone fish (Amphiprion bicintus). They are abundant in coral reef shallow waters. Their main body colour is yellow with two vertical white stripes. If they live in very shallow waters, their back might turn black due to the ultraviolet radiations penetrating the water.
Their diet consists of small planktonic organisms, small algae and small invertebrates. At night they 'sleep' among the tentacles and are gently cradled by the anemone, with which they live in symbiosis and have quite strict ranks in the colony. In a common bubble anemone there are two adults, the female being the biggest and most aggressive. The juvenile might be present and it strikingly resembles the grown up in form and behaviour.

The female will bite the male several times a day in the region where the sexual organs are located. If the female dies the biting obviously stops and the male then changes sex and turns itself into a female. One of the immature males then quickly grows to sexual maturity to replace the male.

Sometimes these fish form colonies on magnificent anemones as well and, due to their size, there might be more than one colony present and not all the fish are anemone fish.

The relationship they establish with the anemone is called mutualism, which means that both the parties have benefits. The anemone is a nettle animal and so its tentacles will powerfully sting whatever comes in contact with them. In case of danger, the anemone fish (that are immune to the anemone's venom due to the mucus present on their skin since the first stages of their embryonic life) can take shelter among the tentacles. The fish in return keep the anemone clean from all kind of debris and residues and try to chase away intruders no matter what their size!

When the spawning season comes, the male elects the most suitable place on the sea bottom, empties it, cleans it and starts a courtship dance. If the female is impressed, it will lay the eggs. The male will then fertilize them and will look after them until they hatch.

I think these are the bravest fish in all the oceans and I, for one, would not dare to enter the water if they were more than a foot long!

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About this Entry

This page contains a single entry by Bryony published on March 12, 2009 3:30 PM.

Emperor featured in 'World's Best Diving & Resorts' was the previous entry in this blog.

Are we on course for another great manta and whale shark season? is the next entry in this blog.

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