New Discovery: Why These Sharks Have a Bright Green Biofluorescent Glow

Scientists have newly discovered why some sharks' biofluorescence allows them to glow bright green.

In this short video, you'll see a small chain catshark and a swell shark glide underwater displaying their bright green glowing rings as they move in total darkness. 

Eerie and unearthly seeming, scientists have now discovered a new form of biofluorescence in these catsharks, emanating from their skin. The discovery is of a group of brominated tryptophan-kynurenine small molecule metabolites which lead to the sharks' glowing look.

What's even more impressive than their coloring, is the fact that their biofluorescence displays antimicrobial activities. A good look that's also a useful one!

But what is the main purpose of this glowing skin on the sharks? Guiding lights.

The glow allows the sharks to be able to see where they are moving as they operate in dark waters." Specific dermal denticles in the chain catshark act as optical light-guides," notes iScience. A rather fancy trick that comes in handy when in the dark. 

Scientists are further questioning the biological function behind the sharks' fluorescence, specifically related to its role in central nervous system signaling, resilience to microbial infections, and photoprotection.

Watch this video and see for yourself how well these small sharks glow green, and the rings they form on their bodies as they do so. Read more about the research on iScience.