London: A glow-in-the-dark shark scares off its predators with "lightsaber-like" spines on its back, a new study has revealed.
The research was carried out on the velvet belly lanternshark, a small shark species found in the deep waters of the Atlantic Ocean and Mediterranean Sea, the BBC reported.
The researchers believe that while the light-up spines can be seen by larger, potentially dangerous fish, they are harder for the shark`s prey to spot.
This diminutive shark lives in the mesopelagic zone of the ocean that has a range between 200m and 1,000m in depth.
Previous research had found that the shark has light-producing cells called photophores in its belly, and it uses this light to camouflage itself.
Lead author Dr Julien Claes, a shark biologist from the Catholic University of Louvain in Belgium, said "Imagine you are below the shark, the shark is swimming and you have the light from the Sun coming down."
He said that if someone is just below the shark they are only going to see a shadow, but if the shark can produce a light identical to sun light then the shadow of the shark is going to disappear.
However, this new study also found that the shark is also luminescent on its top side.
Claes said that there are two spines, one in front of each dorsal fin, and just behind them they have two rows of photophores, which are like lightsabers - they illuminate the spine.
Visual modelling experiments revealed that potential predators are able to see the light from several metres away.
The study has been published in the Nature journal Scientific Reports.