Three deepwater shark species living off the coast of New Zealand have been discovered to glow in the dark, according to scientists.
According to the report, the species were collected in January of last year from the Chatham Rise, a region of ocean floor to the east of New Zealand.
One of them, the kitefin shark, is now the world’s largest luminous vertebrate, measuring up to 180cm in length (5ft 11in).
The bioluminescence of the blackbelly and southern lanternsharks has also been reported.
The three species were already known to marine biologists, but this is the first time they’ve been linked to the phenomenon of bioluminescence (light-emitting organisms).
While many marine animals and insects, such as fireflies, create their own light, this is the first time it has been discovered in larger sharks.
The glowing underbelly of the sharks can help them hide from predators or other threats underneath them, according to the researchers.
Thousands of photophores (light-producing cells) within the sharks’ skin are said to be responsible for the bioluminescence.
The three species studied live in the mesopelagic zone, also known as the twilight zone, which lies between 200 and 1,000 meters deep (the maximum depth reached by sunlight).
The researchers explain that the species in question live in an ecosystem with no places to hide, necessitating the use of counterillumination as a means of camouflage.
The importance of bioluminescence for marine creatures is explained in the analysis by scientists from the Université Catholique de Louvain in Belgium and the National Institute of Water and Atmospheric Research in New Zealand:
It “has always been viewed as a spectacular but rare event at sea, but given the vastness of the deep sea and the presence of luminous species in this zone, it is becoming increasingly clear that producing light at depth must play an important role in structuring the world’s largest ecosystem.”
