NEW YORK, April 25 (UPI) -- The contrast of a catshark's bright green biofluorescence increases at greater ocean depths, and as new research shows, is most obvious at the depths where other members of the species are most likely to be found.
Scientists already knew about the catshark's glow-in-the-dark appearance, but the latest discovery suggests their biofluorescence serves communication purposes -- a revelation for the team of researchers from the American Museum of Natural History.
Using a technique known as microspectrophotometry, researchers were able to determine how catshark eyes process light. They used that knowledge to design a special "shark eye" camera.
The camera revealed the changing contrasts of the sharks' biofluorescence, proving that different catshark species glow most apparently at different depths, allowing them to be more easily recognized by their peers.
"We've already shown that catsharks are brightly fluorescent, and this work takes that research a step further, making the case that biofluorescence makes them easier to see by members of the same species," study co-author John Sparks, a curator in the museum's ichthyology department, said in a news release. "This is one of the first papers on biofluorescence to show a connection between visual capability and fluorescence emission, and a big step toward a functional explanation for fluorescence in fishes."
The new research was published in the journal Scientific Reports.