Deep Dive
Shownotes Transcript
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It's Unexplainable. I'm Noam Hassenfeld. This week, we're going deep underwater, the vast darkness of the ocean, but also the surprising light coming from down there. Reporter Bird Pinkerton has the story of one scientist chasing after that light, about the extraordinary things she's discovered, but also about all the new questions she's revealed along the way.
Even as a little kid, Edie Witter knew she wanted to be an adventurer. I had visions of being some kind of swashbuckling superhero, the female version of Zorro. But then, unlike most daydreamers, Edie actually became a swashbuckling superhero, also known as a marine biologist.
In 1984, she was working with a researcher who wanted to move away from studying animals pulled up in nets and instead explore the ocean through diving. And that is how she found herself on a research vessel off the coast of California, climbing into this special diving suit known as a WASP.
It's called wasp because somebody thought it looked like the insect. It's got this bubble head and a yellow tubular body, and it's got Michelin Man arms with claws on the end. The suit was going to let her see animals in the deep ocean, sort of up close and personal, without being crushed by all the pressure down there. So Edie got inside, and then she was lowered off the back of the boat. As you pass from air to water, everything changes. The colors all change.
Water is a filter. It filters out all the reds and oranges and yellows. So everything turns blue-green, and then it turns deeper and deeper blue. During this descent, Edie had her lights on. But when she got down to around 800 feet, where the water gets really dark, she turned them off. And it was a fireworks display. There was just all of this flashing and glowing and sparkle all around me.
But it's even better than that because you're not viewing it at a distance. You're in the center of the display. In fact, you're part of it because any movement you make triggers flashes all around you. And if I activated the thrusters, these vortices of neon blue liquid light would just shoot up out of the propellers and mixed in would be glowing blue embers. This underwater firework show...
It's a phenomenon called bioluminescence. Animals will use huge amounts of energy to give off light. But watching this light show, it really struck Edie that she didn't understand why they were doing this. It was so breathtakingly beautiful and so utterly confusing because I knew enough about bioluminescence at this point to know how much energy it takes. Life does not use energy to
indiscriminately. And so what was it about all of these light makers and this light making capability that was so essential for life? And I was hooked. I had to know the answer to that question. Edie has spent the last 40 years of her life chasing after answers to that question, sort of trying to figure out why light is so essential to life underwater. And in that process, she's learned a lot.
But she's also discovered even more questions. These mysteries that no one even knew needed solving. Before we get into the mysteries of bioluminescence, let's start with what researchers do know. Bioluminescence is cold chemical light where the chemicals are produced by living creatures. It's the same kind of process that happens when you crack a glow-in-the-dark light stick, for example. Basically, a chemical interaction produces light with very little heat.
And in this case, the chemicals involved are called luciferins and luciferases. Name for Lucifer, like the devil. Well, actually, Lucifer liked the light bringer. Either way, a lot of different organisms have developed versions of these light-making chemicals. Like, Edie would go out on trawling ships that would bring up nets full of deep ocean creatures.
And she says they would just be spewing and dripping and spraying light all over the place. It turns out that about 75% of the animals that you bring up in a net like that, and in some cases as many as 90%, make light. Most of these creatures aren't glowing all the time necessarily. They'll have stripes or patches that flash or maybe they spew some glowing fluid out.
But almost all of them do some kind of light making. It's the rule rather than the exception. Which brings us back to Edie's big central question here. Why are all these animals doing this?
And this is where things get tricky. Because for some of these animals, it's pretty easy to figure out what they're up to. Like, some of these animals are definitely using this light for camouflage. A lot of animals produce bioluminescence from their bellies that exactly matches the color and the intensity of sunlight filtering down through seawater. And if a cloud goes over the sun and dims the sunlight, they dim their belly lights. It's a perfect cloaking device. It's just an amazing trick.
But for other animals, what they're actually using their light for is less obvious. And the actual process of studying these animals up close creates a big problem in Edie's research. To explain why, she told me a story about an eel. This was 1989. Edie was at the very end of sort of a long dive in a submersible. And suddenly she saw this creature swimming out in front of her that just had really weird features. It was super long,
skinny, skinny tail and this huge pelican-like mouth. She quickly realized that this was something called a gulper eel, which is this fish with a long racing stripe along its side. And scientists thought that maybe that racing stripe lit up with bioluminescent light, but they weren't totally sure because they'd mostly interacted with dead versions of this eel that had turned up in nets. To see a live one is very, very rare.
I had never seen one before and have never seen one since. Sweetie was very excited. She pulled out her camera. The pilot was kind of maneuvering the sub to get the eel in better view. Edie was fiddling with all the camera controls. And when I looked up, the fish was gone and there was a brown balloon on a black string. Wow, that was so cool. And I just said, what the hell?
And as I'm looking at it, it splits open along a seam, and I realize it's the fish. The fish had basically shapeshifted itself. Like, it puffed out its throat. He puffed his jaw out. Until it became a balloon. And made himself into this big balloon. And then it deflated it again and sort of turned back into an eel. I didn't know they could do that. I don't know if anybody knew they could do that. And as she kept filming, the eel did the balloon thing...
Again. Got it. I got it on video. At which point, the pilot, Phil Santos, bumps the thrusters in just the right way to slide it into the capture device on the front of the Johnson ceiling, which was an incredible maneuver. Way to go, Phil. And he seals it inside. Oh, man, he got him. Forgive me, fish. Oh, man.
Edie and Phil messaged their colleagues and basically let them know that they were coming up and bringing a live gopher eel to the surface. Rachel, that's a gopher eel. I can't believe I'm saying it in DS. So eventually they sort of got to the shipboard lab. They were under these fluorescent lights.
And Edie lifted the eel out of the container to sort of put it into a tank. And that racing stripe down its side lit up so bright that everybody gasped. It was unquestionably the brightest bioluminescence I've ever seen. I had no idea anything could be so bright that you'd see it over the fluorescent lighting in the lab. So on the one hand, like, this was a triumph, right? Like, Edie had definitively shown that the eel's racing stripe did flash.
But then, on the other hand... Why? I mean... Why was it flashing? Why was it flashing so brightly? Was it blinding to predators? This was this exceptional opportunity to study this rare eel alive. But it's not going to behave normally in the lab. This was the problem that researchers like Edie kept running into. Basically, ocean animals would start acting really weird when you brought them to the surface. Like, they would float at the top of tanks...
And just generally, they would act like they were in a glass cage many, many miles away from their actual home. But meanwhile, in just like a few moments of observing this gulper eel in the wild, Edie had seen something that no one could have predicted. Like, no one would have guessed that the gulper eel turned itself into a balloon. And so she was wondering...
What could she have noticed if she'd seen the eel use its glowing stripe in the wild? What unexpected secrets could she have discovered? It just, it leaves you with so many questions when you see an animal like this. And how can we ever, ever know these things? In an ideal world, Edie could do in the ocean what researchers can do on land. Get close to animals and just watch them do their thing in nature. We just sit behind a blind...
and observe the animals without disturbing them. But unfortunately, she couldn't really do that in the ocean with her submarine. We're just so obtrusive when we go down there with our big, noisy thrusters and bright white lights in a world that everything is about these dim flashes of light. So she decided to create the equivalent of a blind for the ocean, specifically this sort of
very unobtrusive camera. The idea of putting a camera on the bottom wasn't a novel one. People had been putting battery-powered cameras down, but they always put them down with white lights. They needed that light basically to see anything. And Edie did still want to see things. She still wanted light. But she decided to take advantage of this natural blind spot that a lot of deepwater fish have.
Essentially, most life in the ocean produces blue light. That's because blue light, it has short wavelengths, and short wavelengths, they end up traveling a lot further in water than the sort of long wavelengths of red light. So if you make blue light, you get more bang for your glow.
But because most animals in the ocean are only making blue light, they've also only evolved to see blue light. Except this one very crafty predator that Edie started paying attention to called the stoplight fish. The cool thing about the stoplight fish is that it uses its bioluminescence like a sniper scope. It makes red light and it can see red light that other fish can't see. So it can sneak up on them immediately.
illuminate them clearly and see them without being seen. This is useful if you want to eat fish, but it's also useful if, like Edie, you want to study them. And so Edie sort of figured out that the stoplight fish had kind of a filter over its red light that cut out all the other colors completely, figured out how to sort of imitate that, build her own sort of special underwater camera, which she was going to call the Eye in the Sea. She was very excited about it.
And she started to shop it around. And when I'd go to the funding agencies and ask for funding, they'd say, well, what will you discover? And I kept saying, well, that's the point. I don't know. I think we've been scaring stuff away.
So I actually put it together from a bunch of different little sources, and it was really a kludge job. Edie says the eye in the sea was also kind of a kludge job. It was this camera and filter that she designed, and then a thing she called an electronic jellyfish, which was basically some LEDs in an epoxy mold that she
that she wanted to use to kind of attract predators who snack on bioluminescent things to her camera so she could then film them. You could tell what a shoestring operation it was because you could still see the word Ziploc
from the mold that we had used to cast the electronic jellyfish. But Edie figured it was good enough to do the job. And in 2004, she finally got to test her new toy for the very first time. So her team, they lowered the eye in the sea to a spot in the Gulf of Mexico, left it on the bottom overnight. And when they pulled it up in the morning, she reviewed the footage.
I could see that the fish weren't afraid of the red lights. They would swim straight towards them, which is something I'd never seen before. And so I had my window into the deep sea. I was, for the very first time, seeing a world...
as it actually is instead of how it appears when we go down and disturb it. And I was ecstatic. And then things got even better because she got to the part of the footage where the LED lights of that little electronic jellyfish turned on. 86 seconds after it came on for the first time, we recorded a squid over six feet long that was so new to science it could not even be placed in any known scientific family. Not just genus, but family.
Edie was extremely calm. I screamed so loud when that squid appeared that they heard me up on the bridge. And then every time after that, when we recovered the eye and the sea, I had a crowd around me every time. And I went back to the National Science Foundation and I said, this is what we will discover. And they gave me a half a million dollars to do it right. And she did do it right. By mimicking bioluminescence, by creating this camera that didn't disturb animals, she
Edie was able to tease out a lot of new, previously unknown information about how life in the ocean really works. One of the coolest ones was observing giant six-gill sharks that would come in and then they would go vertical in the water, head down, and suck up the muck and blow it out of their gills. And I believe that they were actually sieving food out of the muck
And it goes a long way to explaining how these giants managed to survive in a food-poor environment. They don't only scavenge, but they can also pull food out of the muck. You know, how are we ever going to know these things unless we can observe them like that?
Of course, like seeing a new species, seeing previously unknown behaviors from a species, it really only makes her want to know more about these animals and what they're up to. You always end up with more questions. But with this eye in the sea, with this window into the real ocean world,
Edie finally has a tool that could answer some of those questions. Like, this is this tool that will let her really study animals that glow, like the gulper eel. It'll let her study animals that don't glow, but that feed on those that do, like the six-gill sharks, for example.
It brings her one step closer to answering that question she had, that question of why animals are making so much light and how they're using that glow to mate or hunt or defend themselves against predators. It's, you know, this opportunity finally to explore the largest habitat on Earth and understand more about how the animals behave when we're not
influencing them in some way. But even though this camera is wonderful, Edie says it won't be able to answer all of her questions. Because some of the bioluminescence in the ocean isn't coming from animals that she can watch with a camera. In fact, at first glance, it almost seems like it's not coming from anywhere at all. That's after the break. Support for Unexplainable comes from Greenlight.
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In night black waters, never warmed by the sun, is a world of... Unexplainable.
We're back. I'm still Baird Pinkerton. Before the break, Edie Witter walked us through some of her research, specifically how she figured out how to see the many glowing animals swimming in the ocean and the many other animals that eat them. But a mystery that I keep circling back to is what I saw in that first dive, where there was so much luminescence that I couldn't attribute to specific animals. So that first day in her wasp suit,
When her lights were out, Edie was surrounded by this glowing fireworks display with all the blue embers, etc. But then when she turned her lights back on, the ocean seemed empty. And this turned out to be a common phenomenon
response of many people that had gone down in submersibles and turned out the lights and saw bioluminescence. And they'd say, but when I turned on the lights, there was nothing out there. In the 40 years since that first dive, Edie has solved parts of this mystery. So first of all, she's pretty sure that this glow is coming from something called marine snow.
Marine snow might be familiar if you listened to our episode about the bottom of Challenger Deep, for example. It is this very fundamental part of the ocean's food web and also our carbon cycle. Basically, tiny critters and plants at the surface of the ocean, they swim around, photosynthesize, they store carbon and other nutrients in their tiny bodies, and then they either die or they get eaten and then pooped out.
When that happens, the poop descends and it feeds almost everything that's living below. It's basically like manna from heaven if manna from heaven was poops and those poops gave off life. They become populated apparently with bioluminescent bacteria which cause them to glow. So this is the thing that really excites Edie because we don't yet know everything about how animals actually find this marine snow in order to eat it and that's
kind of a huge hole in our knowledge, right? This is the fundamental basis of the whole ocean food chain. We should know how it works. And she thinks that maybe it works because the bacteria on all this poop, they use this light like a giant screaming sign that says, eat me.
And what's weird about this is it's advantageous to the bioluminescent bacteria because if they get eaten, they get reintroduced into the food-rich gut of an animal where there's plenty of food as compared to the open ocean environment where there's very little for them to survive on. And if this is true, then Edie wonders if it's actually possible if that's why glowing things are so effective at attracting prey in the ocean. No.
Now, Dory, I want you to tell me, do you see anything? I see a... I see a light. A light? Yeah, over there. A fish, like an anglerfish, that sort of scary Finding Nemo fish with the big teeth and then the glowing light that hangs in front of it. It's so...
Pretty. It's possible that that glowing light is sort of imitating a glowing marine snow snack. And then when a hungry fish comes up to eat that snack... I want to touch it. The anglerfish can then gobble it up. Good feeling's gone. Oh!
Researchers don't know for sure that that's why the anglerfish glow is so appealing. Like, they still need to dig into that more. But Edie is also not done. Like, as she's been poking around on this question, she's turned up another riddle in the middle of all this marine snow that she calls the flashback phenomenon. If you go down in a submersible with your lights out and then go dead in the water and flash your lights on, off, on, off, on, off,
Everything flashes back at you in unison out in the water column. And that is still a mystery. I have a hypothesis about what's going on, and I hope to be able to prove it before I give up my career. What's the hypothesis? I'm not telling. I'm not telling.
She will share the basics, though. A lot of this marine snow has cyanobacteria, photosynthetic bacteria on it. And the cyanobacteria is different from the bioluminescent bacteria, to be really clear. So instead of making light, the cyanobacteria just sort of reacts to light. So what Edie thinks is going on here is that when a fish or a submarine, say, flashes out a light—
The cyanobacteria uses that light and it photosynthesizes. And that photosynthesis creates oxygen. And so if you're introducing oxygen, that's the one component of bioluminescence that's absolutely essential. So the cyanobacteria creates oxygen and that lets the other bacteria, the bioluminescent bacteria, bioluminesce. So that's what creates that flash in response. I think. She thinks.
But it's an interesting hypothesis because it wouldn't make sense for marine snow to just be glowing all the time, right? That would be an insane amount of energy. So if this hypothesis is true, then maybe the marine snow only glows when an animal that could eat it is nearby. So the animal sort of flashes its light saying, hello, I'm looking for a snack. And the marine snow flashes back and says, hi, I am a snack. Like, please come eat me.
But it's a really difficult thing to study because a lot of times you can't get it to do it more than once. And so you try to capture it. It's marine snow. It just falls apart. So I've tried to get several microbiologists interested in this, and I think they just think I'm nuts.
Edie really hopes we figure it out, though, because marine snow is the bottom of most of the ocean's food pyramid. Like, understanding how that basic food source for most of the ocean gets noticed and eaten is pretty fundamental. It's absolutely the 101 of life on Earth, and we don't get it yet. We don't understand it. Seems to me that's a pretty big deal. A lot of Edie's research ends up in places like this.
Who's eating whom under the ocean? How are they doing it? How are they using light to attract and defend and blend in or stand out? Basically, what's going on in the deep water? But even after 40 years of research, she's still pretty far from all the answers that she wants.
I don't think people have any concept of how little we understand life on our own planet. We don't even understand how these living systems work, and clearly our future existence depends on it, so this is where we need to be exploring. And to me, it honestly seems kind of overwhelming. It felt like in every story that Edie told, she would...
dive down to answer one question about bioluminescence and its role in the ocean, and then she would come back up with 20 more, just revealing how little we know about gulper eels and deepwater sharks and anglerfish and marine snow. But for Edie, that's what makes the ocean fun.
For me, the appeal of science was the notion of actually seeing something or learning something that nobody else has ever seen or known. That was the thrill. Juanita goes down to explore the light and the dark ocean. She isn't frustrated by all the questions she finds down there. She's excited by them and also kind of delighted by them.
She still remembers how amazing it was 40 years ago when she first went out on a boat and started living all her childhood dreams. This is no way what I thought it would be. It was just so much better. I couldn't believe it. So she wants everyone to spend time feeling that thrill of kind of
charging into the unknown and embracing questions. I think it's innate in all of us. It's actually baked into our DNA. We're all explorers. That's how we learn about the world around us. She cites Alison Gopnik, this psychology professor who claims that nature makes certain things fun in order to reward us for doing things that are good for us. She uses the example of orgasm as how nature gets us to make babies.
And so I think that we ought to have a bumper sticker that exploring is better than sex. All the thrill and none of the baggage. A few months after this first interview, we did a quick fact check with Edie. Did you say that has the package come or could you could you would you mind checking your mail just really quickly? A few minutes later, she came back with this cardboard envelope. So do I get help in it now? Oh, yes, please. Yes.
Edie wanted a bumper sticker to let the world know that exploring is better than sex, so we made her one. That's perfect. She says that she's going to put it on her car, and I, meanwhile, don't have a car to decorate, so this episode is kind of my bumper sticker. Very long bumper sticker. But what I hope you take from it is that even if you're not exploring the deep ocean or exploring the ocean at all,
I really hope that at some point you get to go exploring. If you want to read more about Edie Witter's adventures, please, please check out her book, Below the Edge of Darkness. We could not even begin to fit all the adventures that she's had into just this episode. But meanwhile, this episode was produced by me,
Bird Pinkerton, who was edited by Catherine Wells with help from Meredith Hodnot, Brian Resnick, and Noam Hassenfeld, who also scored the episode. Richard Zima, check the facts. Christian Ayala was on mixing and sound design. Tori Dominguez is our fellow. And Manding Nguyen now lives with both a pigeon and a parrot.
If you have thoughts or dreams about bioluminescence, or if you have ideas for the show, please email us. We're at unexplainable at vox.com. I love reading your emails. And I also really, really love it when people leave reviews or ratings. So if you wanted to make my day, you could do that.
Also, if you enjoyed this episode, you can check out our friends at Vox Conversations next week as they explore the role that Indigenous peoples have played in the global conservation movement. Find that in your favorite podcast app. Unexplainable is part of the Vox Media Podcast Network, and we'll be back next week.