Glowing fish have scientists seeing red

It was staring them in the face, but somehow generations of marine biologists have failed to notice that a lot of fish in the sea glow a fluorescent red, according to a new study.

The study, which appears in the open-access journal BMC Ecology, could change the way we look at the marine environment. It has long been known that red light is not part of the mental universe of marine fish because the sunlight's longest visible wavelengths do not penetrate below a depth of 10 metres. ... Looking through a filter that blocked out the brighter green and blue light waves, they suddenly saw a universe of sea creatures glowing various hues of cherry, crimson, ruby and rust.

"Besides fish, there are lots of fluorescent organisms on the reef, including algae, coral and other small organisms," says Michiels. The red glow was confirmed using spectrometry in laboratory experiments. ... There is also evidence that turning red could serve as a kind of camouflage.

"It may seem strange, using fluorescence to make yourself invisible," says Michiels. "But fish that sit on a reef have a lot of fluorescence around them, so they blend in." ... Hart examined the retina of a fluorescent goby known as Eviota pellucida and found that is "highly likely" that it could see its own fluorescence. The next step is to now determine how fish might use their colour-generating ability to exchange information. - abc