In the ocean near New Zealand, three types of bioluminescent sharks have been described in a recent study .
One of the species, the kite shark, can reach a length of nearly two meters, and the researchers say its radiance makes it the largest known species of luminous vertebrates on Earth.
Three species
Bioluminescence is relatively common in the deep sea among fish and squid, but its presence has been less studied among sharks .
Most of the bioluminescence in the deep sea involves a chemical compound called luciferin that glows when it interacts with oxygen, but in the three sharks described it appears that light is produced in some other way .
The three bioluminescent sharks described are the kite shark , the black-bellied lantern shark, and the southern lantern shark . All three sharks inhabit the mesopelagic or "twilight" zone of the ocean, which extends to depths of 660 to 3,300 feet below the surface.
The researchers aren’t sure what the ability to glow among sharks might do, but they speculate that their glowing bellies could make it harder to see them from below . In the darkness of the deep sea, the ocean surface is a dimly luminous backdrop against which a glowing shark would disappear when viewed from below, hiding it from predators or prey.