The simple answer: They do not “glow in the dark” – they transform the light. Wait what? Yes – you read that right, they transform the ocean’s blue light into a bright green color like this:
Buckle up and put on your nerd hat for a second because this is about to get interesting…
Bioluminescence – The “Glow in the Dark” Effect
With bioluminescence, the organism generates a chemical reaction that produces light energy within their body. These species contain luciferin which is a molecule that produces light when it reacts with oxygen. Here is a pretty awesome example of bioluminescence:
Biofluorescence – How Sharks Appear to “Glow in the Dark”
The Chain Catshark:
and the Swell Shark (Cephaloscyllium ventriosum):
are able to produce a “green glow” affect by transforming the ocean’s blue light into a bright green color. This ability is called biofluorescence.
As if sharks could get any cooler…
Pretty cool, right? But why do they do this? Marine biologist Dr. David Gruber of the University of New York and co-author on the study believes it is so they can see one another in the dark. Apparently males and females show different light patterns according to Dr. Gruber.
It is believed that sharks see color differently than we do, having monochromatic vision, but are able to see blue and green colors. With the sexes having different patterns, it is suggested that they use this glowing ability as a communication for mating. It is also believed that they use this ability for some sort of microbial defensive shield to protect them from bacterial infections.
While a lot is left to be learned, what we have learned so far is pretty amazing to say the least.