Underwater Rainbow: More Than 180 Fish Species Display Remarkable Biofluorescence [VIDEO]

Beneath the ocean, invisible to the human eye, the water is a glowing rainbow of color - bright greens, reds and oranges, produced by various species of fish with natural, and previously unknown, bioflourescent capabilities.

More than 180 species of fish were observed displaying bioflourescence in a new study published in the journal PLOS One, which indicates the phenomenon is common and variable across a range of fish species.

Researchers behind the study suggest the bioflourescence may play a role in mating and communication, and that further exploring the proteins that enable the bioflourescence may lead to developments that will be useful in biomedical research.

Biofluorescence is the capability of an organism to absorb light, transform it, and eject it as a different color.

"We've long known about biofluorescence underwater in organisms like corals, jellyfish, and even in land animals like butterflies and parrots, but fish biofluorescence has been reported in only a few research publications," said co-lead author John Sparks, a curator of ichthyology at the American Museum of Natural History. "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."

Because water quickly absorbs the majority of the visible light spectrum, the marine world is predominately blue. But that blue light has been found to be absorbed by fish and re-emitted as greens, reds and oranges.

"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," said co-lead author David Gruber, an associate professor of biology at Baruch College and a research associate at the American Museum of Natural History. "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."

The research team observed biofluorescence in both cartilaginous fish and boney fish, and many of these fish had yellow filters in their eyes, which would allow them to see the otherwise hidden bioflouescent displays in the water. It is possible, the researchers suggest, that fish can use their secret colors to communicate among themselves without alerting predators.

"The cryptically patterned gobies, flatfishes, eels, and scorpionfishes-these are animals that you'd never normally see during a dive," Sparks said. "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."