Three species of deep sea sharks that glow in the dark found off New Zealand

The kitefin shark. Photo / Daily Telegraph UK, Jérôme Mallefet

The largest known shark that can glow in the dark has been discovered by researchers off the coast of New Zealand.

Scientists discovered that the kitefin shark, the blackbelly lanternshark, and the southern lanternshark, emit a luminescent glow in their habitats deep below the surface of the ocean.

All three deep-sea sharks, which live at depths between 200m and 1000m, were known to science already, but their ability to glow was not documented.

The three species were collected during a fish survey in eastern New Zealand in January last year, and observed in tanks before being dissected and analysed.

The kitefin shark, which can reach up to 1.8m long, is now the world's largest known luminous vertebrate, said the paper published in the journal Frontiers in Marine Science, and also the first documented shark with fully luminous dorsal fins.

The researchers believe that kitefin sharks, which have few if any predators, use their glowing ability to camouflage themselves from prey and to illuminate the ocean floor while hunting, but said more evidence was needed to confirm this theory.

Lead author Jerome Mallefet, of the University of Louvain-la-Neuve, Belgium, said the sharks used a different mechanism to glow than other bioluminescent animals.

"[They] control their light production system by hormones, while most of the bioluminescent organisms seen to date use nerve control to trigger their light," he told Belgian broadcaster RTBF.

The researchers concluded that bioluminescence plays a greater role than previously thought in deep-sea ecosystems.

"Considering the vastness of the deep sea and the occurrence of luminous organisms in this zone, it is now more obvious that producing light at depth must play an important role structuring the biggest ecosystem on our planet," the paper said.

Other luminous marine creatures include algae, crustaceans and jellyfish, and the ability serves different purposes for different species.

Some prey animals, such as jellyfish, use it to startle predators and attract other creatures that prey on their predators.

Other non-marine creatures, such as glow worms, use their light to attract prey.

There are also more than 75 known species of bioluminescent fungi, which only glow at night, attracting insects that land on them and pick up spores to spread in other areas.