Clown fish, iconic among marine organisms, possess a number of unique characteristics, most of them adaptations to their famous symbiosis with sea anemones. They have specialized behavioral characteristics and physical traits, and interesting life cycles.
Behavioral
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The most obvious specialized characteristic of clown fish is their symbiotic relationship with sea anemones. Clown fish live among the stinging tentacles of sea anemones. The clown fish helps the anemone by eating parasites and chasing away the few predators that can nibble on anemones. Meanwhile, the sea anemone provides the clown fish with a safe place to live and spawn. Despite this close relationship, clown fish can thrive in aquariums even without anemones. Clown fish will even spawn in fish tanks without anemones, thought they're rarely found far from an anemone in the wild.
Immunity to Stings
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The clown fish's skin is specialized to accommodate the fish's symbiotic relationship with anemones. The clown fish secretes a thick layer of mucus to protect the fish from the anemones' stinging cells. It appears that the clown fish "acclimates" new anemones to the fish's presence by darting in and out of the anemones' tentacles. This may serve to alter the mucus and trick the anemone to see the clown fish as a part of itself.
Reproduction
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Clown fish also have specialized reproductive characteristics. Clown fish tend their eggs, then allow the baby fish to float among the currents as plankton. This allows a wider clown fish distribution. However, it reduces the chance a clown fish will find a mate. To overcome this, clown fish are protandrous hermaphrodites. This means that all clown fish are born male. In a group, the largest, most dominant clown fish becomes a female. If this female dies, the next largest fish changes sex to become the new female. This makes it easier to find mates, even though many clown fish species are widely distributed.
Coloration
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Clown fish also have specialized coloration. The typical clown fish has an orange body with white stripes and black margins. Marine biologists have discovered more than 28 species of clown fish, though, in a range of colors including reds, maroons, yellows, pinks and mostly black. The number and placement of their stripes vary from species to species, even from specimen to specimen. The bright color warn predators of venom. In this case, though, the clown fish's colors warn predators of the anemones rather than of the fish. Wild clown fish rarely appear far from their host anemone.