In the hubbub of a lively coral reef, all sorts of colours dance before your eyes: the iconic orange clownfish, adorable yellow boxfish and the glinting silver of a barracuda looming in the distance. But what about a fish transforming to a totally different colour right before your eyes?
This is exactly what one diver captured recently when a surgeonfish he was videoing changed from white to black in a few moments.
During a dive on the Great Barrier Reef, Jamie Wilson, a Master Reef Guide who explores the Northern Great Barrier Reef and Coral Sea onboard the Spirit of Freedom liveaboard, noticed something strange.
“I was intrigued by a stream of hundreds of pale surgeonfish high up in the water column, with half of them making a significant detour down to an isolated coral bommie for some reason,” he says. “Going in for a closer look it became apparent they were stopping off for a quick spot of cleaning with a few species of cleaner wrasse.”
That’s when it happened. Right before his eyes, one of the fish dimmed from white to black, as if it had absorbed a pool of dark ink.
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Scientists think these fish change colour at cleaning stations to communicate with the cleaner fish – if they’re pale, they’re ready for a clean.
“Fish are thought to change colour for a variety of reasons – camouflage, communication, mating practice, stress – in this case it's most likely to signal to the cleaner wrasse that it's not a threat and ready for a clean,” says Wilson. Plus, there’s “a potential added benefit of parasites being easier to locate for the cleaner fish” against a white body.
“But they are fish after all,” he adds, “so who can say for sure!”
Image and video credit: Credit: Jamie Wilson, Master Reef Guide
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