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Scientists discover how sharks shine green to get noticed by their mates

There are some species of sharks that in the depths of the sea seem to emit a bright green light. This is a biofluorescence phenomenon that only other sharks of their species can see.

The phenomenon of biofluorescence in certain species of sharks has never been fully studied, at least until today: David Gruber, a professor at the City University of New York, has published with his colleagues a new study on iScience to clarify this mechanism and is quite different from those who use other sea creatures to “shine”.

Gruber, along with his colleague Jason Crawford, a professor at Yale University, analyzed in particular this characteristic in two species of sharks, Cephaloscyllium ventriosum, endemic to the eastern Pacific, and Scyliorhinus retifer, endemic to the western Atlantic.

They first understood that the skin of these two sharks could present two shades, one lighter and one darker, through the extraction of particular chemical substances. They finally discovered that it was a particular fluorescent molecule responsible for the effect, a molecule that was present only in fair skin.

As Gruber himself explains, “the exciting part of this study is the description of a completely new form of marine biofluorescence from sharks – one based on brominated metabolites of small molecules of tryptophan-quinurenine.”

Thanks to this system, they can see each other better without the other animals being able to see the difference in color and in the fluorescence of the skin: “Imagine if you were bright green, but only you could see me bright green and the others could not,” reports Crawford hinting how this feature can be beneficial in many situations. In addition, scientists have discovered that these molecules that carry out biofluorescence also show antimicrobial properties.

Ore ii two scientists intend to exploit this knowledge to see if they can be useful to generate “molecular systems for imaging in the laboratory or in medicine,” according to Crawford, according to which “imaging is an incredibly important biomedical target that these types of systems could help progress in the future.”