EXCLUSIVE: How "Glowing" Sharks See Each Other | National Geographic

This amazing thing happened a few years ago. We accidentally found a fluorescent fish, and then that led us to over 200 fluorescent fish, including two species of sharks. I wanted to film these sharks in their natural world with the shark eye camera and see, essentially, what their world looks like through their eye.

Humans see in three colors: red, green, and blue. As soon as we go underwater, we start losing all the other colors quickly, and it becomes dark and blue. These biofluorescent sharks that we're looking at are called swell sharks. These sharks had only one visual pigment, and it was only right at the intersection of blue and green. They're in a blue world where everything is blue, but they're capable of turning blue into green.

Once we learned what the pigment of the shark eye was like, we filtered a very sensitive camera we had, a Red Epic, to have the same color sensitivity as the shark at 120 ft. In this canyon, we were just using the blue ocean light. This was difficult for us humans, but the sharks can still see amazingly well, and that makes sense because they've been down there for 440 million years. They've been living in an environment with very little life.

This was a huge step for us because we didn't even know if the swell sharks, the fluorescent sharks, could see this. With this study, now we know yes, they can see the fluorescence among themselves. This almost seems like when it was discovered that bats were communicating with sound outside of human detection and that there was a whole mode of communication going on. With sharks, it could be something similar—how they're using it.

Now we could even go further and further. We're in this era where we're losing species at a rate that we haven't seen in millions of years. So in trying to connect with nature, it's important to kind of empathize with nature and to even see what these animals are seeing. By putting ourselves behind the shark's eye, it gives us a portal into their life.