Marine biologists studying sharks off the east coast of New Zealand have discovered three deep-sea shark species that glow in the dark, including one, the Kitefin Shark, that has now become the largest bioluminous vertebrate known to biological science.
Bioluminescence is produced by an enzyme reaction within organisms and many deep sea marine animals like Angler, Dragon and Loose-Jawed Fish produce their own light to to mimic and lure prey and to find food.
Several sharks, like the Cookiecutter Shark, also use blue or green light bioluminescence to mimic other fish and lure prey. However, this is the first time that it has been found in larger sharks, measuring nearly six feet, such as the kitefin shark, or in blackbelly lantern sharks, and southern lantern sharks.
Bioluminescence is difficult property to study since animals usually lose their ability to luminesce when caught due to stress or damage received when handling.
However, images were taken of the glowing sharks, in their natural habit, during a fish survey conducted at Chatham Rise off the east coast of New Zealand, in January 2020. Kitefin shark, which can grow to nearly 6 ft in length, have been dubbed by the researchers, who discovered the fish glowing, as “giant luminous sharks”.
The research team from the Université Catholique de Louvain also discovered green-blue luminescence in blackbelly lantern sharks and southern lantern sharks.
The three species of shark were already familiar to marine biologists but this is the first time that bioluminescence has been identified in them. It’s believed that the sharks’ luminous under-bellies are used as camouflage or counter-illumination to help them hide from predators that can see their distinct silhouettes beneath them. All of the sharks studied are from the meso-pelagic zone, also called the twilight zone, which ranges from 200 to 1,000 metres beneath sea level.
In the case of kitefin sharks, which also has a glowing dorsal fin and very few predators, it is possible that it uses its blue-green glow to illuminate the sea floor while it looks for food, or as camouflage that allows it to get close to prey.
The glowing sharks study has been published in the Frontiers in Marine Science journal.
More Shark Facts…
The Shark with the largest teeth relative to body size?
The shark with the biggest teeth relative to its body size is the largetooth cookiecutter shark, Isistius Plutodus, named after the goddess Isis, and measuring around 1 feet 4 inches in total length. Its lower jaw’s triangular teeth are proportionately huge, and help the shark gouge out plugs of flesh in sneak attacks on much larger marine creatures.