WASHINGTON, Jan. 9 (UPI) -- It's not a horse of a different color but fish emitting reds, greens and oranges not visible to the human eye and U.S. researchers say they want to know why.
About 180 species of fish experience biofluorescence, which occurs when an organism absorbs blue light, transforms it and emits it as another color.
A team of researchers from the American Museum of Natural History and other scientific organizations published a study Wednesday in PLOS ONE, reporting the findings of the first in-depth look at biofluorescence in fish, find several varieties gave off a colorful glow in and around reefs, CNN reported Thursday.
"We've long known about biofluorescence underwater in organisms like corals, jellyfish, and even in land animals like butterflies and parrots," said study co-author John Sparks, curator in the museum's Department of Ichthyology.
He said the team happened on an eel that glowed green where he and his partner were studying a reef in the Cayman Islands. The discovery in a photograph of the eel lighting up beneath the blue lights they used led to four more trips to different parts of the world to examine the underwater color show.
"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 said.
The museum said in a release many fish have yellow filters in their eyes, "possibly allowing them to see the otherwise hidden fluorescent displays taking place in the water."
Sparks said the research paper published by PLOS ONE "is the first to look at the wide distribution of biofluorescence across fishes, and it opens up a number of new research areas."