Meet the world’s largest bioluminescent predator discovered underwater

The ocean’s depths hold countless wonders, many of which remain shrouded in darkness until they suddenly surprise us. Deep beneath the surface exists a whole world of creatures that glow, changing the blackness into a realm of glowing bioluminescence.

But what happens if the largest of these creatures comes from this underwater world and seems almost unreal?

A study has revealed the largest bioluminescent creature

A 2021 scientific study published in Frontiers has revealed the kitefin shark, also known by its Latin name Dalatias licha, as the largest known vertebrate capable of natural bioluminescence, the ability to produce light within its own body. Specimens of this deep-sea denizen were collected during a January 2020 expedition off New Zealand’s Chatham Rise, a region reaching depths of 200 to 1,000 meters, and their glowing properties were analyzed under controlled conditions.

At nearly 1.8 meters (5 ft 11 in) long, the kitefin shark’s blue-green glow emanates from its belly and fins, making it beautiful. This glow comes from specialized light-producing cells called photophores, which contain photocytes, tiny cells that emit light between 455 and 486 nanometers. Importantly, researchers ruled out any involvement of bioluminescent bacteria or known chemical reactions, suggesting a unique, internally stimulated mechanism.

Why does the shark glow?

The kitefin shark’s glow serves a couple of clever purposes. Firstly, the light on its belly helps it blend in with the faint light from above, making it harder for predators to spot it from below, which is a popular trick known as counterillumination. Another theory is that the glow helps this slow-moving shark find food. The light might help it see the seafloor better while hunting or sneak up on prey without being noticed.

The study named other species

The study also documented two smaller glowing species, the blackbelly lanternshark and the southern lanternshark, which tells how widespread bioluminescence may be among sharks.

Not all glowing creatures are Bioluminescent

Even though the kitefin shark is the biggest known bioluminescent vertebrate, it's not the biggest glowing animal in the ocean. That title goes to the whale shark, which can grow up to 61 feet long. But here’s the difference: whale sharks don’t glow through bioluminescence; instead, they use biofluorescence. That means they absorb light, usually ultraviolet light, and then re-emit it at a visible wavelength, kind of like a natural glow-in-the-dark effect.

This difference is important because it shows that not all glowing sea creatures light up in the same way.