Researchers have identified a previously unknown family of small-molecule metabolite that is responsible for the bioflourescence of deepwater sharks that allows them to see each other in the darkest of depths.
David Gruber, a professor at City University of New York, and Jason Crawford, a professor at Yale University, extracted chemicals from the skin samples of swell sharks and the chain catsharks –which had varying skin tones and found that the fluorescent molecule was only present in the light skin. The findings were published in the latest issue of the journal iScience.
“Studying biofluorescence in the ocean is like a constantly evolving mystery novel, with new clues being provided as we move the research forward,” Gruber said. “The exciting part of this study is the description of an entirely new form of marine biofluorescence from sharks—one that is based on brominated tryptophan-kynurenine small-molecule metabolites.”
This mechanism is different from animals in the upper ocean, such as jellyfish and corals, that commonly use green fluorescent proteins as mechanisms to transform blue light into other colors.
“It is also interesting that these biofluorescent molecules display antimicrobial properties. These catsharks live on the ocean bottom, yet we don’t see any biofouling or growth, so this could help explain yet another amazing feature of shark skin,” Gruber says. “This study opens new questions related to potential function of biofluorescence in central nervous system signaling, resilience to microbial infections, and photoprotection.”