Scientists have long known that some lucky animals have the special ability to absorb light and emit it as a different glowing color, a phenomenon known as biofluorescence, but a new study led by scientists from the American Museum of Natural History suggests that some of the marine animals that appear normal to humans under regular lighting may actually emit brilliant neon colors of red, orange and green deep underwater.

"The cryptically patterned gobies, flatfishes, eels, and scorpion fishes -- these are animals that you'd never normally see during a dive, to our eyes, they blend right into their environment. But to a fish that has a yellow intraocular filter, they must stick out like a sore thumb," said John Sparks, a curator in the Museum's Department of Ichthyology and one of the lead authors of the study, said.

Scientists had to use blue lights and cameras with yellow filters to capture the glow because they are invisible to the human eye. "By designing scientific lighting that mimics the ocean's light along with cameras that can capture the animals' fluorescent light, we can now catch a glimpse of this hidden biofluorescent universe," biologist David Gruber of Baruch College and the American Museum of Natural History, said.

The researchers reported their findings, titled "The Covert World of Fish Biofluorescence: A Phylogenetically Widespread and Phenotypically Variable Phenomenon," which was published in the journal PLOS One. In their report, the researchers said they have identified more than 180 species of biofluorescent fishes and showed how some fish glow for varied reasons such as for communicating and mating.

"Many shallow reef inhabitants and fish have the capabilities to detect fluorescent light and may be using biofluorescence in similar fashions to how animals use bioluminescence, such as to find mates and to camouflage," Sparks explained.

Sparks also said that biofluorescence underwater in organisms like corals, jellyfish and even in land animals like butterflies and parrots has been long known but fish biofluorescence has been reported in only a few research publications."This paper is the first to look at the wide distribution of biofluorescence across fishes, and it opens up a number of new research areas," he said.

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