Meet the Kitefin Shark

We’ve got nothing but glowing reviews for this bioluminescent shark

The ocean is full of mysteries and every once in a while scientists get a glimpse of something extraordinary. Last year, I was delighted to see, for the first time, scientists had captured photos of one of those camera-shy deep-sea creatures: the kitefin shark.

Kitefin sharks live deep below the ocean’s surface in an area called (cue music) the twilight zone. This is an ocean layer around about 650 to 3,300 feet below the surface. It gets its name because it lies nearly out of reach of the sun’s rays. There are all sorts of interesting creatures that live in the twilight zone including the heavenly-named but terrifying sea angels, the legendary giant squid and frigid colonies of icefish.

The twilight zone is not completely dark. If you were swimming down there you might see the glow from bioluminescent animals like the kitefin shark. There are 57 shark species that are suspected to produce light and the kitefin shark is the largest, clocking in at six feet of glow-in-the-dark splendor. That makes it the largest bioluminescent vertebrate in the world. Just imagine—swimming in near-darkness when suddenly a human-sized shark-shaped glowing being swims past you. I don’t know if I’d be frozen in awe or swimming away as fast as I can.

Kitefin Shark Illustration

On land, we often use light to get people’s attention with neon signs and stoplights. The kitefin shark uses light for the exact opposite reason: to hide. A very faint glow still comes down from the sun even in the deep and dark twilight zone. The similar bluish-green light a kitefin shark emits allows it to blend in and become nearly invisible, making it easier to hunt and harder to be hunted. This extra camouflage gives the kitefin shark a much-needed leg up in the competition. It is one of the slowest sharks in the world (learn about another slow-moving shark, the Greenland shark).

This might not be the only way kitefin sharks use their glow.

In fact, one researcher referred to them as “MacGyvers of light.” Their glowing bellies might help illuminate delectable treats on the sea floor like shrimp or squid. It can also help them avoid the endless scroll on dating apps. Their internal glow accentuates their reproductive organs, which could help them attract mates. And there may be ways they use their light-up powers that we haven’t figured out yet. For instance, the dorsal fin of a kitefin shark glows, but scientists haven’t been able to determine why.

Kitefin sharks get their glow in a very interesting way: through hormones, specifically melatonin. You might be familiar with it because it helps humans fall asleep. For kitefin sharks, it helps them light up the twilight. Scientists are still learning how these hormones help produce this shark’s light show—it’s one of the many mysteries these creatures will take to the deep sea (for now).

Every morning I read through scientific discoveries hoping for weird and wonderful wildlife, like the kitefin shark. It makes my day when I learn these seemingly extraterrestrial creatures amazingly live on our blue planet. These incredible discoveries wouldn’t be possible without scientists dedicating their lives to studying our ocean. That’s why it is so important to fund world class ocean science and continuing exploration of the wonders under the sea.

Our work is focused on solving some of the greatest threats facing our ocean today. We bring people, science and policy together to champion innovative solutions and fight for a sustainable ocean.
Read more
View Current Posts
Back to Top Up Arrow