ANEMONEFISH (NEMO!)

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Anemonefish, otherwise recognised as ‘nemo’ fish, are abundant on our local and deep dive sites. They are feisty fish and not afraid of divers, often straying unusually far (up to 5ft from their anemone) to check us out.Anemonefish live symbiotically with anemones and are very rarely seen without one another. While anemone will sting potential prey or predators that come in contact with it, the Anemonefish acclimatize over time by acquiring a layer of mucus that prevents stinging and establishes them as residents in the anenome.

The juveniles are small and black, with white spots, while the adults are the familiar orange with black and white stripes.

They are protandrous hermaphrodites (able to change their gender).  When the fish hatch from the eggs, during the first stage of life, all are male. As they develop into juveniles, the fish are neither male nor female but instead have elements of both sexual organs. Once adult, they mature into fully functional males. They remain male until the female of the breeding pair dies. At this point, the adult male will transform into a female and the most dominant, non-reproductive juvenile will then mature to be the male in the new breeding pair. We usually see one family of fish on each anemone, with two larger fish which are the breeding pair and any number of juveniles. Of the pair, the largest will be female and slightly smaller the male. The juveniles do not have a typical growth cycle; they instead will remain small due a combination of bullying and hormones.

The Anemonefish also have an interesting spawning process. They spawn close to full moon, all year round. In Southern African waters however, it is particularly between November – April. The pair will “nip” on the side of the anemone, so it withdraws its tentacles and creates an opening 10cm in diameter where the female lays her eggs to be fertilized by the male. The eggs are pinhead in size and initially a dark, rusty colour. However, by the time they hatch are golden with the eye (a black spot) visible. The majority of the time the male will guard the eggs, keeping them oxygenated and removing the dead ones to remove contamination. Once hatched, the babies will eat minute plankton and after one week leave to search for their own anemone.

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