David Gruber
2,436,913 views • 13:54

I'm a marine biologist and an explorer-photographer with National Geographic, but I want to share a secret. This image is totally incorrect, totally incorrect. I see a couple of people crying in the back that I've blown their idea of mermaids. All right, the mermaid is indeed real, but anyone who's gone on a dive will know that the ocean looks more like this. It's because the ocean is this massive filter, and as soon as you start going underwater, you're going to lose your colors, and it's going to get dark and blue very quickly.

But we're humans — we're terrestrial mammals. And we've got trichromatic vision, so we see in red, green and blue, and we're just complete color addicts. We love eye-popping color, and we try to bring this eye-popping color underwater with us.

So there's been a long and sordid history of bringing color underwater, and it starts 88 years ago with Bill Longley and Charles Martin, who were trying to take the first underwater color photograph. And they're in there with old-school scuba suits, where you're pumping air down to them, and they've got a pontoon of high-explosive magnesium powder, and the poor people at the surface are not sure when they're going to pull the string when they've got their frame in focus, and — boom! — a pound of high explosives would go off so they could put a little bit of light underwater and get an image like this beautiful hogfish. I mean, it's a gorgeous image, but this is not real. They're creating an artificial environment so we can satisfy our own addiction to color.

And looking at it the other way, what we've been finding is that instead of bringing color underwater with us, that we've been looking at the blue ocean, and it's a crucible of blue, and these animals living there for millions of years have been evolving all sorts of ways to take in that blue light and give off other colors. And here's just a little sample of what this secret world looks like. It's like an underwater light show.


Again, what we're seeing here is blue light hitting this image. These animals are absorbing the blue light and immediately transforming this light.

So if you think about it, the ocean is 71 percent of the planet, and blue light can extend down to almost a 1,000 meters. As we go down underwater, after about 10 meters, all the red is gone. So if you see anything under 10 meters that's red, it's an animal transforming and creating its own red. This is the largest single monochromatic blue environment on our planet.

And my gateway into this world of biofluorescence begins with corals. And I want to give a full TED Talk on corals and just how cool these things are. One of the things that they do, one of their miraculous feats, is they produce lots of these fluorescent proteins, fluorescent molecules. And in this coral, it could be making up to 14 percent of its body mass — could be this fluorescent protein. So you wouldn't be making, like, 14 percent muscle and not using it, so it's likely doing something that has a functional role. And for the last 10, 15 years, this was so special to me, because this molecule has turned out to be one of the most revolutionary tools in biomedical science, and it's allowing us to better see inside ourselves.

So, how do I study this? In order to study biofluorescence, we swim at night. And when I started out, I was just using these blue duct-tape filters over my strobe, so I could make sure I'm actually seeing the light that's being transformed by the animals. We're making an exhibit for the Museum of Natural History, and we're trying to show off how great the fluorescent corals are on the reef, and something happened that just blew me away: this. In the middle of our corals, is this green fluorescent fish. It's the first time we've ever seen a green fluorescent fish or any vertebrate for that matter. And we're rubbing our eyes, checking the filters, thinking that somebody's maybe playing a joke on us with the camera, but the eel was real.

It was the first green fluorescent eel that we found, and this just changed my trajectory completely. So I had to put down my corals and team up with a fish scientist, John Sparks, and begin a search around the world to see how prevalent this phenomenon is. And fish are much more interesting than corals, because they have really advanced vision, and some of the fish even have, the way that I was photographing it, they have lenses in their eyes that would magnify the fluorescence. So I wanted to seek this out further.

So we designed a new set of gear and we're scouring the reefs around the world, looking for fluorescent life. And it's a bit like "E.T. phone home." We're out there swimming with this blue light, and we're looking for a response, for animals to be absorbing the light and transferring this back to us. And eventually, we found our photobombing Kaupichphys eel. It's a really shy, reclusive eel that we know almost nothing about. They're only about the size of my finger, and they spend about 99.9 percent of their time hidden under a rock. But these eels do come out to mate under full-moon nights, and that full-moon night translates underwater to blue. Perhaps they're using this as a way to see each other, quickly find each other, mate, go back into their hole for the next long stint of time. But then we started to find other fluorescent marine life, like this green fluorescent bream, with its, like, racing stripes along its head and its nape, and it's almost camouflaged and fluorescing at the same intensity as the fluorescent coral there.

After this fish, we were introduced to this red fluorescent scorpionfish cloaked and hidden on this rock. The only time we've ever seen this, it's either on red fluorescent algae or red fluorescent coral.

Later, we found this stealthy green fluorescent lizardfish. These lizardfish come in many varieties, and they look almost exactly alike under white light. But if you look at them under fluorescent light, you see lots of patterns, you can really see the differences among them. And in total — we just reported this last year — we found over 200 species of biofluorescent fish.

One of my inspirations is French artist and biologist Jean Painlevé. He really captures this entrepreneuring, creative spirit in biology. He would design his own gear, make his own cameras, and he was fascinated with the seahorse, Hippocampus erectus, and he filmed for the first time the seahorse giving birth. So this is the male seahorse. They were one of the first fish to start swimming upright with their brain above their head. The males give birth, just phenomenal creatures. So he stayed awake for days. He even put this electrical visor on his head that would shock him, so he could capture this moment. Now, I wish I could have shown Painlevé the moment where we found biofluorescent seahorses in the exact same species that he was studying. And here's our footage.


They're the most cryptic fish. You could be swimming right on top of them and not see the seahorse. They would blend right into the algae, which would also fluoresce red, but they've got great vision, and they go through this long mating ritual, and perhaps they're using it in that effect.

But things got pretty edgy when we found green fluorescence in the stingray, because stingrays are in the Elasmobranch class, which includes ... sharks. So I'm, like, a coral biologist. Somebody's got to go down and check to see if the sharks are fluorescent. And there I am.


And I was like, "Maybe I should go back to corals."


It turns out that these sharks are not fluorescent. And then we found it. In a deep, dark canyon off the coast of California, we found the first biofluorescent swellshark, right underneath all the surfers. Here it is. They're just about a meter long. It's called a swellshark. And they call them a swellshark because if they're threatened, they can gulp down water and blow up like an inner tube, about twice their size, and wedge themselves under a rock, so they don't get eaten by a predator. And here is our first footage of these biofluorescent swellsharks. Just magnificent — I mean, they're showing these distinct patterns, and there are areas that are fluorescent and areas that are not fluorescent, but they've also got these twinkling spots on them that are much brighter than other parts of the shark.

But this is all beautiful to see. I was like, this is gorgeous. But what does it mean to the shark? Can they see this? And we looked in the literature, and nothing was known about this shark's vision. So I took this shark to eye specialist Ellis Loew at Cornell University, and we found out that this shark sees discretely and acutely in the blue-green interface, probably about 100 times better than we can see in the dark, but they only see blue-green. So what it's doing is taking this blue world and it's absorbing the blue, creating green. It's creating contrast that they can indeed see. So we have a model, showing that it creates an ability for them to see all these patterns. And males and females also have, we're finding, distinct patterns among them.

But our last find came really just a few miles from where we are now, in the Solomon Islands. Swimming at night, I encountered the first biofluorescent sea turtle. So now it's going from fish and sharks into reptiles, which, again, this is only one month old, but it shows us that we know almost nothing about this hawksbill turtle's vision. And it makes me think about how much more there is to learn. And here in the Solomon Islands, there's only a few thousand breeding females of this species left, and this is one of the hotspots for them. So it shows us how much we need to really protect these animals while they're still here, and understand them.

In thinking about biofluorescence, I wanted to know, how deep does it go? Does this go all the way to the bottom of the ocean? So we started using submarines, and we equipped them with special blue lights on the front here. And we dropped down, and we noticed one important thing — that as we get down to 1,000 meters, it drops off. There's no biofluorescent marine life down there, below 1,000 meters — almost nothing, it's just darkness. So it's mainly a shallow phenomenon. And below 1,000 meters, we encountered the bioluminescent zone, where nine out of 10 animals are actually making their own lights and flashing and blinking.

As I try to get deeper, this is slapping on a one-person submarine suit — some people call this my "Jacques Cousteau meets Woody Allen" moment.


But as we explore down here, I was thinking about: How do we interact with life delicately? Because we're entering a new age of exploration, where we have to take great care, and we have to set examples how we explore. So I've teamed up with roboticist Rob Wood at Harvard University, and we've been designing squishy underwater robot fingers, so we can delicately interact with the marine life down there. The idea is that most of our technologies to explore the deep ocean come from oil and gas and military, who, you know, they're not really caring to be gentle. Some corals could be 1,000 years old. You don't want to just go and crush them with a big claw. So my dream is something like this. At night, I'm in a submarine, I have force-feedback gloves, and I could delicately set up a lab in the front of my submarine, where the squishy robot fingers are delicately collecting and putting things in jars, and we can conduct our research.

Back to the powerful applied applications. Here, you're looking at a living brain that's using the DNA of fluorescent marine creatures, this one from jellyfish and corals, to illuminate the living brain and see its connections. It's funny that we're using RGB just to kind of satisfy our own human intuition, so we can see our brains better. And even more mind-blowing, is my close colleague Vincent Pieribone at Yale, who has actually designed and engineered a fluorescent protein that responds to voltage. So he could see when a single neuron fires. You're essentially looking at a portal into consciousness that was designed by marine creatures.

So this brings me all back to perspective and relationship. From deep space, our universe looks like a human brain cell, and then here we are in the deep ocean, and we're finding marine creatures and cells that can illuminate the human mind. And it's my hope that with illuminated minds, we could ponder the overarching interconnectedness of all life, and fathom how much more lies in store if we keep our oceans healthy.

Thank you.