Near New Zealand, researchers have discovered three species of luminous sharks. That reports the British newspaper The Guardian Tuesday based on research by scientists from the Belgian Université Catholique de Louvain and the National Institute of Water and Atmospheric Research (NIWA) in New Zealand.
Bioluminescence – the emission of light by organisms – is more common in deep-sea animals, but it is the first time this has been seen in the false dogfish, devil lantern shark and southern lantern shark.
The false dogfish can grow to be 180 centimeters long, making it the largest known vertebrate that can emit light. The researchers say the discovery shows how little people still know about the deep sea. These sharks all live between 200 meters and 1 kilometer deep in the water, an area known as the Twilight Zone.
Why the sharks’ bellies light up is not yet known. But the scientists suspect the two smaller shark species use it as a protection against attacks from the deep. That explanation does not apply to the false dogfish because it has no known natural enemies. The shark may be using its glowing belly to spot prey. Further research should prove that.
“Given the vastness of the deep ocean and how many luminous organisms exist in this area, it is becoming increasingly clear that producing light at that depth plays an important role in our planet’s largest ecosystem,” the researchers write. The deep ocean is also the least explored ecosystem.