Dr David Gruber and other scientists uncover glow in the dark sharks which use biofluorescence

SCIENTISTS have discovered for the first time how a group of sharks use biofluorescence, or glowing, to communicate with each other.

SCIENTISTS have discovered for the first time how a group of sharks use biofluorescence, or glowing, to communicate with each other.

The research, published in the Nature journal Scientific Reports, found that two species of sharks, the chain catshark and the swell shark, both absorb the blue light of the ocean and reemit it at lower energy wavelengths, which results in the fish glowing bright green.

Lead author of the research, Dr David Gruber, said he was aware of this process called biofluorescence in coral but was unaware that it may be found in sharks as well.

“It is kind of like out of a sci fi novel,” he told News Corp Australia. “In 2014 we were studying biofluorescence in coral and we accidentally got photobombed by a green fluorescent eel and so we went on an expedition and found 180 species of biofluorescent fish.”

New discovery ... Dr David Gruber is the lead author on the groundbreaking research. Picture: YouTube

Dr Gruber and his team found that catsharks and swell sharks live about 500 metres below the surface of the water, where sunlight produces a blue light.

An unidentified pigment in the sharks’ skin re-emits the animal as bright green.

It is different from bioluminescence, where animals either produce their own light through a series of chemical reactions, or host other organisms that give off light.

The scientists found that these sharks have one visual pigment for detecting colour, which means they see colour in a blue-green spectrum, as opposed to humans who see things in red, blue and green.

Different image ... What the shark looks like normally. Picture: David Gruber

After a few dives, the team created a shark-eye camera which mimics how a shark would see underwater.

While using the shark-eye camera, the sharks were found to emit a bright green glow.

The researchers also found that the male and female sharks displayed different glowing patterns, suggesting that perhaps the pop of colour is a mating ritual.

The research expands our knowledge of sharks, which were previously thought to rely on smell, hearing and electrical signals to find their way around.

Mysteries of the deep ... Scientists study how animals see below the surface of the water. Picture: David Gruber

“The next step is to get behind more animals,” Dr Gruber said. “When a shark only has one visual pigment it is easier. Turtles get more complicated because they have visuals almost more complicated than humans.

“What I am really hoping is that it will draw us closer to these relatives. We emerged from the sea 200 million years ago ... it has not been that long that humans have been going back underwater, just a few hundred years, so it seems there are lots of secrets left to uncover.”