[RADIOLAB INTRO]

JAD ABUMRAD: All right, Bobby. Would you like to—would you like to do it?

ROBERT KRULWICH: Yeah. Go ahead and start me and I'll just go—I'll just take it through.

JAD: Okay.

JAD: Three, two, one. Hey, I'm Jad Abumrad

ROBERT: I'm Robert Krulwich.

JAD: This is Radiolab.

ROBERT: And today I've brought us a little—a little story.

LUCY COOKE: Hello!

ROBERT: Lucy?

ROBERT: That is ...

LUCY COOKE: Robert!

ROBERT: Oh, great! Okay ...

ROBERT: A sort of slippery mystery.

JAD: Slippery mystery. Okay.

ROBERT: And the mystery comes from this woman, Lucy Cooke.

LUCY COOKE: I'm the author of The Truth About Animals.

ROBERT: And it's a rip-roaring ...

LUCY COOKE: Which is filled with strange stories.

ROBERT: It's really—like, we're, like, feasting on this book. Okay.

ROBERT: So Lucy—so Lucy wrote a book, and the book is actually a collection of animal profiles which come from her journalism. And I just—I love it. I love it a lot. And so I called her up, and we just started talking about ...

LUCY COOKE: Frogs.

ROBERT: All sorts of animals.

LUCY COOKE: Bats.

ROBERT: Sloths.

LUCY COOKE: The island of dwarf stone sloths in Panama.

ROBERT: I have no idea what that means.

ROBERT: We talked about birds.

ROBERT: Birds are like turtles?

LUCY COOKE: No, no, no, no, no!

ROBERT: We talked about ...

LUCY COOKE: If you're a female panda ...

ROBERT: ... bears.

LUCY COOKE: What you're really looking for in a male panda is one that can squirt his pee quite high up a tree.

ROBERT: But what I really wanted to talk to Lucy about ...

ROBERT: Well, I'm gonna stop right there and switch quickly to eels.

ROBERT: ... was eels.

ROBERT: Because we only have 33 minutes left, and I don't want to ...

LUCY COOKE: Oh my God, and the eel's so good.

ROBERT: And the eels are so good.

ROBERT: Because as you will soon learn, the story of the eel is really—and this is strange to think about—the limits of human knowledge.

LUCY COOKE: Yeah, are you ready to rock and roll?

ROBERT: You could just start with, like, tell me when you first—you know, first encountered this creature.

LUCY COOKE: Oh, I was a very geeky only child, and what I loved to do more than anything else in the world was, my father sunk an old Victorian bath into the garden and that became my Narnia. And I'd sort of disappear into this watery kingdom and, you know, was obsessed with creating the perfect pond ecosystem out of this rather sterile tub for human ablution. It became my—it was—it was—it was everything to me. So every Sunday, I'd nag my dad. "Can we go to the ditches of Romney Marsh? Please, Dad!" And he'd sort of take me off and we'd go. He made me a net to catch things with—out of a pair of old net curtains that I'd sort of trawl through the ditches of Romney Marsh and catch all these wonderful creatures. You know, pond skaters and newts and frogs, and—and I'd bring them back to my—my tub. But eels became my holy grail, because the thing about eels—I don't know Robert, have you ever tried to catch one?

ROBERT: No, I would never even think to try to catch them because they're ucky and slimy and they remind me of snakes.

LUCY COOKE: Yeah. No, I wanted to, because I wanted to have all animals, much like Noah. I wanted all animals to be represented in my pond.

ROBERT: You had a list!

LUCY COOKE: Yeah, I had a list. And the eel, it was impossible. I caught them, but then trying to grab them with my own bare hands was always a complete disaster because they are, as you say, extremely slippery. They would just slither out of my hands and then shoot off in the grass, more like a snake than a fish out of water. But had I managed to get eels to join my—my happy pond party, I would have been a little bit horrified because I now know they would have eaten all the other guests, because they are voracious predators and they will eat any other creature that they can get their mouths around, including each other.

ROBERT: Which, Lucy explained, was proven rather graphically in a famous 1930s experiment in France.

LUCY COOKE: Yeah. So basically in the 1930s, there are a couple of researchers in Paris who placed a thousand elvers which are young eels, they're about three inches long in a tank of water. And they fed them every day. But even so, after a year of the one thousand elvers there were only 71 left.

ROBERT: Because they all got sick and died, or what?

LUCY COOKE: No. They ate each other.

ROBERT: Oh!

LUCY COOKE: And so the 71 survivors a year later were three times as long as they were before. And then three months later, after what a local journalist reported as, "daily scenes of cannibalism," there was one champion that was left and it was a female—whoo-hoo!—measuring a foot in length. And she lived four more years on her own, and could have lived a lot longer if the Nazis hadn't invaded Paris and inadvertently cut off her supply of worms and she died.

ROBERT: So ...

LUCY COOKE: Those Nazis have got a lot to answer for. The eel story has got it all.

ROBERT: It does. It has everything.

LUCY COOKE: It's got it all. It's even got Naz—it's got Freud, it's got Nazis. It's got an international gonads championship. It's got everything.

JAD: Wait. International gonads championship?

ROBERT: Yes, yes. Because there has been and there still is a very simple question we've been asking about eels, and that is: where do they come from?

JAD: That's a question?

ROBERT: Yes. People have been fishing them and eating them and hunting them and studying them, as you're about to find out, forever and ever and ever. For such an important animal, it's remarkable it has kept the secret of its origins from every human being.

JAD: Wait, how can it be—how can it—how can that be that—how can that be true?

ROBERT: It's not for lack of trying.

LUCY COOKE: It's taken a very, very, very long time to try and figure out the mysteries of the eel.

ROBERT: And Lucy says this question: where do eels come from?

LUCY COOKE: That is something that has tormented men of science since Aristotle. So he thought that eels were spontaneously generated by the action of water on mud, and that the worm casts that we see in sand were actually embryonic eels boiling out of the earth.

ROBERT: Wait a second. So water would slap, slap, slap, slap, slap against seashore rocks or sand or something, and then—squirt!—up would pop an eel?

LUCY COOKE: Yeah. Exactly. That was—that was Aristotle's solution. That wasn't his finest hour. And then the great Roman naturalist Pliny the Elder, he thought that eels rubbed themselves against rocks and the scrapings came to life.

ROBERT: You mean, like it's dandruff? Like, eel dandruff? Like, rub, rub, rub, rub—boing!—I've got a baby?

LUCY COOKE: [laughs] Exactly, yeah. The ideas of where they came from were utterly fanciful. You know, there was one Reverend Bishop who claimed in the Middle Ages that he'd seen eels being born out of the thatching of his roof. There were others that thought that they came from dewdrops, but only at certain times of year.

ROBERT: Well, what about when you get a microscope? Like, these are the superstars of science. So van Leeuwenhoek, he looked at them, right? So he could have seen it.

LUCY COOKE: Yeah. So he thought that they gave birth to live young like mammals do, because he sort of got his microscope out and he looked inside an eel and he thought he saw little baby eels swimming around inside a bigger eel. But actually, what he'd seen were parasitic worms inside a swim bladder. So he was wrong.

ROBERT: What about Carl Linnaeus? As long as we're dealing with the great—Linnaeus who categorized all life, did he have an eel idea?

LUCY COOKE: Yeah, he did. He thought that they were—gave birth to live young. But the unfortunate thing was that he was actually looking at the wrong creature. It wasn't an eel. It was a very similar-looking fish called an eelpout, which is a completely unrelated type of fish. So he was very wide of the mark.

ROBERT: So let me just—let me get rid of the clutter of all of these non-Italians. Because in your story, it turns out that Italians are the ones for—I guess because they are—they have eels in their rivers, they just thought, "We've got to figure this out." I noticed that Leonardo in The Last Supper, are the disciples eating eel for their Passover seder? Is that what's going on there?

LUCY COOKE: I believe so. I think there are—there are eels on the table in the painting of The Last Supper.

ROBERT: Wow. Okay.

LUCY COOKE: So I mean, the Italians who are very good with food, took a great interest in the riddle of the origins of the eel. And at a time in the 18th century, while Italy at that time was a load of warring states, there was no sort of sense of national identity. And the—there were a sort of small band of Italian scientists who decided that somehow that they would—they would forge an identity for their nation, not through revolution but by finding the gonads of the eel. It's a novel approach to politics.

ROBERT: [laughs] Yes! Did they succeed in Italianizing the gonad? Like, did they find them in Italian eels?

LUCY COOKE: Oh, they made a lot of attempts, basically. So it started in 1707 when a local surgeon found an unusually plump eel amongst the many thousands that were caught every day on the Po River delta. And he sliced it open and he saw what he thought was an ovary and eggs, and he sent this pregnant fish to his friend the esteemed naturalist Vallisneri, who hastily proclaimed the centuries-long search for the evils—the evils?—the eels' private parts was finally over. And unfortunately, he was wrong. But this then sort of ignited this interest amongst the Italian scientific establishment who decided it was a matter of extreme importance to find the true ovaries of the eel, and they came up with this plan. They thought, "I know what we're going to do. All we have to do is put out there a reward."

ROBERT: Like, if you find the gonads of an eel, you'll get a thousand ducats.

LUCY COOKE: Exactly. So what happened was they got an eel stuffed with eggs, but unfortunately the wily fisherman had filled his eel with the eggs from another fish.

ROBERT: Oh! He cheated! He put in another—oh!

LUCY COOKE: Yeah, he cheated. So there was a bit of a blow for the Italians' gonad hunt. And that went on pause for about 50 years. And then in 1777, a fresh, fat, slimy suspect flopped up on the shores of Comacchio, and it was examined by the great anatomist Carlo Mondini, who was a professor at the nearby University of Bologna. And he realized that the frilled ribbons inside the eel's abdomen weren't fringes of fatty tissue, which is what they'd previously thought, but they were the female eel's evasive ovaries. So bingo! Ovaries found.

JAD: Wait. Frilled fringes? What exactly did the ovaries look like?

ROBERT: So if you think of a—if you think of seaweed.

JAD: Mm-hmm.

ROBERT: When you open up a female eel, there is a little place in the middle of her tummy that looks like little wispy bits of flesh with little dots on the end.

JAD: Oh, that look like seaweed.

ROBERT: Yeah.

JAD: That's the ovaries?

ROBERT: Yeah. Turns out that those are their ovaries.

JAD: How'd they—how'd they miss that?

ROBERT: I don't know. You know, I think you—they don't look like anything like mammalian ovaries, they don't look like other fish ovaries, so they just—they were hiding in plain sight.

JAD: And so then the male ovaries, do you have any sense of what those ...?

ROBERT: The male testes they're called.

JAD: The male testes, I'm sorry. Yeah, male testes.

LUCY COOKE: Testicles still missing, though. And what's amazing about the eel story which is just absolutely extraordinary, is we now have another character who turns up. The mission to complete the eels' genital jigsaw you might say, fell to an unlikely character, Sigmund Freud.

ROBERT: He's an eel hunter?

LUCY COOKE: Well, he was a student at the time at the University of Vienna, and it was his first ever academic job was he spent a summer trying to track down the testicles of the eel. He was—he was investigating the claim of a Polish professor who had claimed that he had discovered the testicles of the eel, but he hadn't saved them or he hadn't used a microscope, or for some reason there was no proof. So Freud was given the task of proving this claim. So for weeks, every day from 8:00 in the morning until 5:00 in the afternoon in a hot smelly laboratory, he sliced open long, phallocentric fish in search of their testicles. Freud was completely consumed by it and—and failed. He just—he couldn't substantiate this Polish professor's claims, and he moved on to look for the seat of desire in—in another animal, namely the human.

ROBERT: So Lucy says now jump ahead about 30 years to around the 1890s.

LUCY COOKE: A male eel finally exposed itself. And it was to this chap Giovanni Grassi.

ROBERT: An Italian biologist who one day ...

LUCY COOKE: Found an eel swimming off the coast of Italy.

ROBERT: Scooped it up, brought it back to his lab, cut it open. And saw finally and with certainty, this is a little cloudy—cloudy how he knew this, but he said, "Yup. These are the right things. This is the testes and those are the sperm."

LUCY COOKE: Nothing short of miraculous.

ROBERT: So did he get a big, like—a prize? A reward?

LUCY COOKE: Well, I like to think that there was an enormous great big cup shaped like a pair of testicles.

ROBERT: [laughs] Okay, let's just plop—let's just keep that thought in our heads and move on.

JAD: But okay. So testes located, ovaries located.

ROBERT: Right.

JAD: Two great mysteries of nature solved.

ROBERT: But there's another one. There's another even bigger one.

JAD: Mmm!

ROBERT: Where do they go to do this thing? Where do the testes and the eggs go—squick, squick—and make a baby?

JAD: What do you mean? Where, like, in the water?

ROBERT: In the water, yes.

JAD: But ...

ROBERT: But where on Earth?

JAD: Huh.

ROBERT: On Earth, Jad. That turns out to be an even deeper mystery. That's after the break.

[MEGAN: Hi, this is Megan and I'm calling from cloudy Ithaca, New York. Radiolab is supported in part by the Alfred P. Sloan Foundation, enhancing public understanding of science and technology in the modern world. More information about Sloan at www.sloan.org]

JAD: Radiolab. Okay, so Robert you left us with the eel mysteries one and two solved.

ROBERT: We know where their sex parts are, yeah.

JAD: Testes located, ovaries located.

ROBERT: Right. Now you want to know how they have sex and where they have sex.

JAD: I don't—it's funny, I didn't—I mean, now that you ask the question I do want to know the answer, but I wasn't ...

ROBERT: Well, this has proven to be, Jad, a very hard question. And it was only a while ago that we found a clue.

LUCY COOKE: Grassi was on a bit of a roll. So he'd found the testicles of the eel.

ROBERT: And the clue was found by our Italian scholar, Grassi.

LUCY COOKE: He does something incredibly ingenious, because as early as the 1850s there were these tiny, weeny transparent fish the shape and thickness of a willow leaf with bulbous black eyes and these—grrr!—snaggly, gruesome buck teeth, had been documented washing up in huge numbers on the shores of Italy. And these sort of minuscule monsters were just sort of dismissed as just another one of the many, many millions of nondescript marine creatures that inhabit the sea. But Grassi, he thought to himself, "I think that those are actually—they're not an adult fish. They're a larvae of a fish."

ROBERT: Oh, so they're a baby. I just don't know what they're about to grow up and to become.

LUCY COOKE: Yeah. And what he did that was so incredibly clever was that he counted their vertebrae, and it averaged at about 115. And then he looked for a match in an adult species of fish, and he found it in the European freshwater eel. It's just an—an amazing piece of biological detective work, I think.

ROBERT: And it revealed that baby eels were living along the coastlines and then washing into the mouths of rivers all over the world. Italy and Spain and Japan and ...

BECCA BRESSLER: And where are we right now?

ROBERT: ... the great state of New York.

CHRIS BOUSER: We are on the Fall Kill Creek in Poughkeepsie, New York, where this creek enters the Hudson River.

ROBERT: We have eels right around here in New York City.

JAD: We do.

ROBERT: We do. In Poughkeepsie.

CHRIS BOUSER: About 75 miles north of New York City.

ROBERT: So our producer Becca Bressler and I went up to Poughkeepsie to meet this man Chris Bouser.

CHRIS BOUSER: I am the Hudson River estuary educator for the New York State Department of Environmental Conservation.

ROBERT: And Chris explained to us when these tiny little baby eels ...

CHRIS BOUSER: Like little pieces of transparent linguine.

ROBERT: ... arrive in the Hudson River ...

CHRIS BOUSER: They're only about two inches long. And they arrive here by the hundreds of thousands. And then they quickly when they get here ...

ROBERT: They start transforming.

CHRIS BOUSER: ... going through these physiological changes that makes puberty look like a kid's birthday party what these eels go through.

ROBERT: Basically, these little eels settle down at the bottom of the river.

CHRIS BOUSER: And blend in with the river bottoms.

ROBERT: And grow ...

CHRIS BOUSER: And grow ...

ROBERT: And grow and grow and grow and grow and grow.

CHRIS BOUSER: There's only one way to see how big the eels in there are, and that's to go in there and see them. We want to catch you some adult eels. Or ...

ROBERT: I'm happy to do it. Not exactly happy to do it. I'm just kind of ...

CHRIS BOUSER: Or if you'd rather just get the eels, our team can go ahead and get them right now.

ROBERT: No, no, no, no. I'm not gonna wuss out on this. I'm gonna do this.

CHRIS BOUSER: Keep going then.

ROBERT: Okay.

CHRIS BOUSER: Just keep going.

ROBERT: But let me ask you. Like, the first time you actually touched one with your own hands, what—tell me what it felt like?

CHRIS BOUSER: Silky love. People think of eels as being slimy. No, they're satiny, silky. They just feel like these beautiful, muscular, well-adapted miracles of evolution. You cannot touch an eel or hold an eel in your hand without feeling some weird love and wisdom coming to pass.

ROBERT: Do you have any brothers and sisters?

CHRIS BOUSER: I do. They think I'm strange.

ROBERT: Okay. So ...

ROBERT: How am I gonna catch anything with these rubber gloves?

CHRIS BOUSER: Ah! Here comes Aiden to show you how.

ROBERT: Chris and a few of his colleagues and Becca and I, we put on these canvas overalls, rubber boots, rubber gloves.

FEMALE RESEARCHER: This is for you.

ROBERT: And we were given nets.

ROBERT: Oh!

FEMALE RESEARCHER: This is what we're gonna be using to catch the eels.

ROBERT: Okay.

CHRIS BOUSER: Scoop them with that net!

ROBERT: Okay.

ROBERT: And one of the researchers, she was netless. Instead, she had this long metal rod that connected to a backpack.

FEMALE RESEARCHER: When—I'm going to turn the backpack on. Whenever the backpack is on it's putting electricity in the water. So ...

ROBERT: Basically, electrical current comes out of the backpack into the metal rod into the water ...

CHRIS BOUSER: To gently stun and coax these eels out of their hiding places.

ROBERT: And once that happens, that's my cue to grab one.

FEMALE RESEARCHER: All right. So is everybody ready?

BECCA: Ready. Yes.

CHRIS BOUSER: Sarah Mount, you're in charge. Sarah Mount's giving directions now.

ROBERT: And so we walked out deeper into the creek.

ROBERT: Okay. We're now mid-creek.

ROBERT: And eventually we stopped. And Sarah, the researcher with the backpack ...

SARAH MOUNT: All right. Backpack on.

ROBERT: ... sent some electricity into the water. And ...

BECCA: There's an eel!

ROBERT: Up they came.

SARAH MOUNT: Oh, there's one right there. There you go.

ROBERT: One after another, these long shiny creatures slithering through the water.

BECCA: There's two eels in here.

ROBERT: Some of them are over three feet long. So I tried to net one.

ROBERT: Oh! That wasn't a small one! Whoa! Almost had it.

CHRIS BOUSER: Wait, before you do that. Everybody look up here and smile, just because it's a great picture. Go get them!

SARAH MOUNT: Everybody ready?

ROBERT: But I just kept missing and missing ...

ROBERT: But I didn't catch any.

ROBERT: ... and missing. Until finally in my net, a two-foot long shiny eel.

SARAH MOUNT: If you want to take your glove off and touch it with your bare hand, you're welcome to.

ROBERT: Yes, I would love to.

SARAH MOUNT: You can feel that silky, smooth ...

ROBERT: Silky love coming my way. If I can get off my rubbery glove for the silky love. Okay, mister eel. Ooh, yeah it is kind of—it is kind of silky. Yeah. Oh, he doesn't feel bad at all. What do you think little fella?

SARAH MOUNT: Do you feel any danger?

ROBERT: No. I'm going to call her Florence. Florence the eel. Hey, here's your tail.

ROBERT: I should say that eels can survive out of water, even crawl through the grass for hours. But eventually, I did let Florence go back into the water, only to learn from Chris and his team that Florence wasn't actually wasn't a Florence. That Florence in fact wasn't either a male or a female. Because this particular eel didn't have ovaries or testes. And in fact, most of the eels that we saw on that day in the river didn't have ovaries or testes and were all sexless.

JAD: Hmm.

ROBERT: Because this is the thing that happens the world over is that when eels are in rivers they hang out, they grow, they get bigger and they're waiting essentially for this moment that comes almost at the midnight hour of their lives. It's—it's like the ringing of a bell. When just as they're about to get their long-awaited ovaries and testes, they come up from the bottom of the riverbed and then they make their way down the river and back out into the sea. And then they just disappear. You can't find them.

JAD: What do you mean they just disappear? They—like, they can't follow them?

ROBERT: They cannot be followed.

JAD: Oh, is that why it was so hard for them to find the sex parts, because maybe the ones they were finding ...

ROBERT: Well, they had to find an older one, yeah.

JAD: That didn't have them yet.

ROBERT: Yeah.

JAD: Oh, that explains a lot of it. Yeah.

ROBERT: So they're like the opposite of salmon. Salmon start in the—in the rivers and go down to the sea. Spend a long time in the ocean and then come back up the rivers. This is the—eels are the un-salmon.

JAD: Oh, interesting.

ROBERT: They—they start in the ocean somewhere. They go up to the rivers, they get big and mature, then they head back to the ocean somewhere. The question is where?

JAD: Oh, interesting.

ROBERT: Nobody knows! I mean, this is weird. Like ...

JAD: Do they all go to the same place?

ROBERT: Well, you'll find out.

LUCY COOKE: Okay, all right. Well, shall I—shall I try and tell the story of Johannes Schmidt very quickly then?

ROBERT: So back to those early days of scientific eel-hunting in the late-1800s, nobody had seen an adult eel out in the sea, strange as that may be. But then there's this guy ...

LUCY COOKE: Oceanographer, Johannes Schmidt.

ROBERT: Who thought, "Well, wait a second. The eels we know go out somewhere into the ocean, die, and have babies. We see those babies showing up at the tops of rivers all over the world, so let's track the babies backwards," he thought. Starting with the biggest ones, then look for smaller babies then smaller babies still. And the smallest, smallest babies will probably be right at the nest where the parents die and those babies are born.

LUCY COOKE: It's worth noting that Johannes Schmidt was described as being, and I quote, "Pathologically ambitious."

ROBERT: Because remember what Schmidt's looking for are these tiny, tiny little eels.

LUCY COOKE: The shape and thickness of a willow leaf.

ROBERT: Like a three-inch long translucent piece of wiggly flesh. So small. And we're talking about the Atlantic Ocean. So, like, how are you gonna pull this off?

LUCY COOKE: Well, he had rather fortuitously—he'd just married the heiress to the Carlsberg Brewery, and they were probably the best lager company in the world for an aspiring oceanographer to hitch his wagon to, because they were known to fund ocean exploration. So he'd married the heiress and then he was then, because he had all these funds, he was able to spend, after she'd married him he then disappeared to sea for 20 years.

ROBERT: 20 years!

LUCY COOKE: Combing the world's oceans.

ROBERT: From Cairo and Alexandria all the way to Virginia.

LUCY COOKE: With progressively finer nets.

ROBERT: Looking for smaller and smaller and then smaller baby eels.

LUCY COOKE: His breakthrough came in 1921 when he found one that was a quarter of an inch long, which he presumed could be no more than a day or two old.

ROBERT: And Schmidt found this eel ...

LUCY COOKE: Slap-bang in the middle of the Bermuda Triangle.

ROBERT: In the Sargasso Sea. First of all, it's so far away from Italy and Spain and Europe, it's kind of near the Carolinas off North America. And it's a very strange place.

LUCY COOKE: It's unusually salty. It's filled with an underwater forest of sargassum seaweed and very, very, very deep. I think at some places it's four miles deep.

ROBERT: Whoa!

ROBERT: It is the only sea, the only thing we call a sea that doesn't have land around it. It's this zone of very quiet water surrounded by roaring currents going in a big circle around it.

JAD: And the idea is this is the place where all eels come to have their babies?

ROBERT: No, not all eels. Because there's eels all over the world. But for the Atlantic eel, the Sargasso is the place. At least that's—that's the theory. Because since Schmidt's big discovery in 1921, we have been trying to confirm it. So for instance, a few years ago, scientists in Europe tagged 400 eels to see where they would go. They went into the Mediterranean, but most of them died and very few got out into the Atlantic. And, you know, a few of them went kind of wandering toward Africa. Then a year ago roughly, there was another story about a single tagged eel.

ROBERT: Can you tell me the story of that eel?

CHRIS BOUSER: I sure can.

ROBERT: It was an eel that started up in the St. Lawrence River in Canada, who would eventually become a female eel.

CHRIS BOUSER: She heads south, sniffs around. According to the tag, she then heads due east.

ROBERT: Heads first towards Scotland, then reverses her way back to Maine.

CHRIS BOUSER: And starts a quick beeline south. I don't mean south-ish. I mean, south. South like she is following one of the magnetic longitudes of the planet. She heads down, and somewhere at the edge of the Sargasso Sea the tag comes off. We don't know if it falls off, we don't know if it was eaten. We don't know what happens. All we know is that's the end of the road of the tag, but the fate of that female eel we don't know.

LUCY COOKE: Exactly. And we don't know because even today—and in fact, I got an email yesterday from perhaps the world's leading eel scientist, and he explains to me that sadly after many, many, many years, much effort, and millions of dollars spent, still no one had managed to actually track an eel all the way from the rivers of Europe to the Sargasso.

ROBERT: But they tried, right?

LUCY COOKE: Exactly. They—they sunk swollen eel temptresses into the Sargasso, hoping that they would attract males and they could catch them in flagrante and then finally prove that—that definitely it was observed eels mating. But still, it's never been seen, it's never been witnessed.

ROBERT: Maybe the guys aren't there. Maybe they got the wrong place. Or maybe the guys are shy or maybe the guys know a science experiment when they see one and are just not gonna tell. I don't know which of those three.

LUCY COOKE: Or they are actually breeding on the moon and falling out of the sky, raining on the Sargasso. We can't—we can't rule that out.

CHRIS BOUSER: We don't know where exactly. We don't know how exactly. But somewhere in the Sargasso Sea, there's the miracle of a fertilized eel egg.

ROBERT: Miracle because no one's ever seen it?

CHRIS BOUSER: Correct. Ever.

ROBERT: In the wild.

CHRIS BOUSER: There is a secret sauce with eels that we have not solved. Forget the Coca-Cola recipe, eel sex is the real mystery of our generation. And we think we know roughly where in the Sargasso Sea it happens, but that's a think not a know. We have never witnessed in the wild eel egg fertilization.

ROBERT: Well, I know you're not an eel. So let me ask you like, have you imagined where all the—let's assume for the sake of argument that there is a place that Atlantic eels go to, and it is a place where they have sex and it's a place where they have babies and it's a place where they die. In your imagination, what does that place look like? Speaking as a human.

CHRIS BOUSER: In my imagination, and make sure that line makes it in [laughs], in my imagination—and again, this is without any proof but in my imagination, I like to think of some deeper waters of the Sargasso Sea, somewhere between Bermuda and Puerto Rico. It's a quiet place. It's a dark place. It's beyond the reach of all but the barest of wavelengths of light up top. And I think that with these eels, you know, I've often wondered, do they pair off discreetly? Is there sort of a massive orgy of eels that happen? And I like to think of eels as once they get there, there's gotta be some sort of primitive ichthyological celebration, that feeling of, "My gosh! I have finally accomplished a 30-year, 3,000-mile journey! All of us have!" But I'm gonna go back to what we were talking about, how much I love the mystery. I don't like to overthink it.

ROBERT: Oh, you don't want to even think about this.

CHRIS BOUSER: I don't want to overthink it. Because again, I almost respect and love the mystery so much that I see, like, in the eel movie, right? Fade to black. [laughs] Cue the music, the fireside lighting, you know? Slow dissolve. Fade to black. Tah-dah!

ROBERT: This piece was produced by Becca Bressler and Matt Kielty. Special thanks to the men and women of the Hudson River Estuary Program who helped us with this project and brought their equipment and their bodies and—and their strange clothing down to the creek. And to Clay Hiles of the Hudson River Foundation who set us up with these folks, and to Kim Airstrup.

JAD: And to all eels that are on the cusp ...

ROBERT: Yes.

JAD: ... of that great journey into the unknown.

ROBERT: Who still won't tell us what they know.

JAD: Deep—deepwater nursery ...

ROBERT: Yeah. Thank you, eels.

JAD: ... of mystery.

ROBERT: Yes.

JAD: Keep doing it, eels. Keep doing it.

ROBERT: And they're doing it, by the way, right around now. So it's in the—in hurricane season.

JAD: [laughs]

ROBERT: So for a variety of reasons, these animals are just not telling.

JAD: Well, we are not done yet. Luckily for all of us, we have one more mystery of the animal kingdom. It's actually sort of a two parter, but it deals with one creature, another creature, not eels, but a different one. Tiny little sea creature that is so beautifully, insanely weird and wild and loud—loud—that you're gonna want to hear it. So I would urge you to stay tuned because that new animal mystery is coming up after the break. Radiolab will continue in a moment.

[LISTENER: Hi, this is Barbie calling from Portland, Oregon. Radiolab is supported in part by the Alfred P. Sloan Foundation, enhancing public understanding of science and technology in the modern world. More information about Sloan at www.sloan.org.]

JAD: Hey, I'm Jad Abumrad.

ROBERT: I'm Robert Krulwich.

JAD: This is Radiolab. Today, we have a mystery that is ...

ROBERT: Vanishingly tiny ...

JAD: Shockingly hot ...

ROBERT: ... and manages to combine submarines ...

JAD: Keanu Reeves ...

ROBERT: Red Lobster ...

JAD: ... and Game of Thrones.

ROBERT: And of course our producer Molly Webster and many members of her family.

MOLLY WEBSTER: Hello, hello, hello, hello? Where are the children?

ROBERT: So now you want to begin in the beautiful state of South Carolina?

MOLLY: South Carolina.

JAD: It's on a pier.

MOLLY: Yeah.

MOLLY: Is my radio gear waterproof?

CHILD: Yeah.

MOLLY: No.

MOLLY: On a dock.

MOLLY: Oh, okay, so we're gonna walk down to the dock.

CHILD: Pfft, pfft, pfft!

MOLLY: Which is just like this place where they all put boats in the water.

CHILD: I—I love boats!

MOLLY: And that's where we always ...

CHILD: Oh chicka-lacka-lacka-boom-boom.

MOLLY: Shut up! I'm gonna explain what a dock is. [laughs]

MOLLY: Okay. My parents recently moved to this marshy swampy area near the Intracoastal Waterway, which is like a connecting series of salty channels. And we grew up in Ohio and so this is like a totally different landscape than what we grew up in.

CHILD: Okay.

MOLLY: And those little people would be my nieces and nephews.

CHILD: I'm riding my bike so we can ride it back.

CHRISSY WEBSTER: Hear that America? Those are my children getting along and compromising.

MOLLY: That would be Chrissy Webster, one of my sisters.

CHRISSY WEBSTER: And we sound a lot alike.

MOLLY: Anyway. So—okay, so this is the story. The story is so when my parents first moved there, I remember going out on the docks with my dad, and we were sort of looking at the beautiful marsh, right? And there was this really weird sound, like, coming off the water.

CHILD: Water.

MOLLY: I recently took my nieces and nephew out to see if they could hear it.

MOLLY: [whispers] Okay, we're gonna be ...

CHILD: [whispers] I'm in position.

MOLLY: Okay, so we're not gonna move, and we're not gonna squeak.

CHILD: We're not gonna talk.

MOLLY: We're not gonna talk.

CHILD: Okay.

MOLLY: So we lean down off the dock ...

MOLLY: Okay, ready? Now we're gonna see if we can hear it.

CHILD: Huh! [crackling]

MOLLY: Oh my gosh, I hear some crackles!

JAD: That crackling sound?

MOLLY: Yeah.

JAD: What is that?

MOLLY: That was the question.

MOLLY: What does it sound like?

CHILD: It sounds—it sounds like Rice Krispies. Yeah!

MOLLY: Most of the scientists you talk to say it sounds like bacon frying or twigs crackling in a fire.

JAD: Huh.

ROBERT: Maybe you have a large Perrier factory just up the hall.

MOLLY: Yeah, I would say that except there's no bubbles popping, like, on the water.

ROBERT: Oh! so it's not a gaseous emission. It's a clickety clack

MOLLY: Let me just play you a better recording.

JAD: Yeah, pull it up.

MOLLY: Wait, do I have to put it through the producer PC? Wait, uh ...

JAD: Oh wait, here we go.

[ARCHIVE CLIP: [crackling]]

MOLLY: This is actually an underwater recording.

ROBERT: Oh my God! Oh! Gosh, in a teeny world, that would be like the Fourth of July.

MOLLY: Yeah!

ROBERT: Wow.

MOLLY: Yeah.

ROBERT: It's bigger than bacon ...

JAD: Bigger than bacon ...

ROBERT: Bigger than bacon.

MOLLY: I don't—it depends on how much bacon you're frying.

JAD: So what—all right, what is the sound? What is it?

MOLLY: This sound is a very tiny ...

CHILD: No, wait, wait, wait, wait, wait, wait, wait!

MOLLY: Let me just back it up a second.

MICHEL VERSLUIS: Well, the story started in the '40s.

MOLLY: That's Michel Versluis.

MICHEL VERSLUIS: Professor of physical acoustics and medical acoustics at the University of Twente, in the Netherlands.

MOLLY: Basically, what he said is World War II is the first war where we're, like, really using submarines and sonar. And so you've got all of these US Navy submarines down deep in the ocean and they're, like, listening out for the enemy. But what happens is all they hear is this, like, crazy crackling sound.

MICHEL VERSLUIS: The sound levels that were measured—so this loud—this sound is very, very intense.

MOLLY: He says in some instances, it was actually interfering with the sonar.

MICHEL VERSLUIS: That—that was a bit of a problem.

MOLLY: Yeah, so I found a—I found a classified document that was declassified right after the war, where the Navy, they actually hired—they actually hired this scientist, this guy named Martin Johnson. This is in California.

MICHEL VERSLUIS: I believe it was in San Diego at Scripps.

MOLLY: They hired this guy to figure out, what is the sound? Like, what is the sound we're hearing, like, all over the ocean?

JAD: What is it already?

MOLLY: Jad's like, just tell me what the damn sound is?

JAD: Yes!

MOLLY: Well, it turns out—I don't want to go too fast here.

MICHEL VERSLUIS: It was noted in those years that that sound originated from ...

CHILD: The shrimpy, shrimpies.

CHILD: Shrimpies!

MOLLY: It was a shrimp.

CHILD: Oh yeah!

MOLLY: The shrimp is called a snapping shrimp or a pistol shrimp.

ROBERT: Ooooh. [laughs] Pistol shrimp.

JAD: Oooh. I like that.

ROBERT: Yeah.

JAD: Pistol. Pew-pew-pew!

MOLLY: And interestingly, I found these, like, old Navy recordings ...

[ARCHIVE CLIP: They explored about one foot in length.]

MOLLY: ... that they would give to the Navy guys where they had to learn the sounds they were hearing coming in through the ship and through the sonar.

[ARCHIVE CLIP: In your work with the expendable radio sonobuoy, you will probably hear many sounds other than submarine sounds.]

MOLLY: It was like, "This is the sound of a snapping shrimp."

[ARCHIVE CLIP: Snapping shrimp. It produces a harsh clicking noise. [clicking]]

MOLLY: And I was like okay, shrimp, sonar. Cool. I get it. Meh? Thought maybe it would end there. And then I found what felt to me to be a crazy article, which was this newspaper clipping from 1946. Basically says shrimps helped win the war.

JAD: What?

MOLLY: And I was like, what? And it's about how the American Navy admitted that one of their tactical things during, like, World War II was that they would hide their submarines in the beds of these shrimp so, like, the Japanese submarines couldn't detect our ships.

JAD: Oh my goodness!

ROBERT: So it was like a marine invisibility cloak?

MOLLY: Yes. And according to Michel, the US would also ...

MICHEL VERSLUIS: Put speakers on the hull of the ships to simulate snapping shrimp.

MOLLY: Wait, what? [laughs]

MICHEL VERSLUIS: Yes.

ROBERT: It was sound camo.

MOLLY: Yeah.

JAD: So wait, wait, wait. Are these shrimp, are they like normal—normal shrimp-cocktail types shrimp?

MOLLY: Well ...

MICHEL VERSLUIS: They're about five centimeters, two inches.

MOLLY: So like smaller than a shrimp I might eat?

MICHEL VERSLUIS: Well it depends what sort of shrimp you eat.

MOLLY: I don't know, whatever ...

MICHEL VERSLUIS: There is ...

MOLLY: ... whatever Red Lobster serves. No, I don't know. [laughs]

JAD: Wait a second. If they're that small, how are they making that sound?

MOLLY: That is an excellent question.

MOLLY: Wait. Where do you think the sound comes from?

CHILD: I'm thinking it's—the shrimpies are eating their food. And the noise is their little teeth.

MOLLY: Oooh, shrimpy teeth!

CHILD: I think it—for me, I think it comes from they're, like, snappy claw thingies.

MOLLY: And that's what you would think, right? Like, especially if you look at these things up close.

NANCY KNOWLTON: They have two front claws, and the claws aren't the same on each side.

MOLLY: That's Nancy Knowlton, a marine biologist, snapping shrimp expert.

NANCY KNOWLTON: There's a claw that's specialized for pinching.

MOLLY: And that claw's tiny.

NANCY KNOWLTON: And a claw that's specialized for snapping.

MOLLY: And that claw is, like, exponentially bigger. It's, like, 10 times, or 20—maybe three times bigger. [laughs]

NANCY KNOWLTON: It's quite a bit bigger. And so they use it to defend themselves against potential predators or competitors. They're very territorial.

MOLLY: She says when one shrimp runs into another shrimp ...

NANCY KNOWLTON: They can get into these prolonged snapping matches where they snap at each other to show ...

MOLLY: Me! Me! Me! Me! Me! Me!

NANCY KNOWLTON: ... who's bigger and stronger.

MOLLY: Meeee! Okay, fine.

NANCY KNOWLTON: And they can pretty much judge how big they are by the power of the snap.

MOLLY: All of which is to say, my niece Sophie's guess ...

CHILD: I think it comes from their, like, snappy claw thingies.

MOLLY: ... is, like, yeah, of course, it's like the two sides of the claw just, like, snapping together.

MICHEL VERSLUIS: It's just like you snap your fingers like this. [snaps fingers]

JAD: Just a snap.

MOLLY: Snap.

NANCY KNOWLTON: But that turns out not to be true.

MOLLY: So not true.

MICHEL VERSLUIS: Two things were wrong, basically, with that picture. I don't know if you've ever tried to clap your hands in a swimming pool underwater ...

MOLLY: [laughs] Yes.

MICHEL VERSLUIS: ... but it's very difficult.

MOLLY: Yeah. You don't feel very smart when you try it. Doesn't work.

MICHEL VERSLUIS: But there's not a lot of sound. And that is because there's a lubrication layer of water in between that prevents direct mechanical contact, or ...

MOLLY: Yes, there's this lubricating layer between the two claw halves, and it makes snapping hard.

MICHEL VERSLUIS: And the second problem was that ...

MOLLY: The sound just seemed way too loud. Like, when they measured the decibel level of a single snap ...

MICHEL VERSLUIS: That's about 220 decibels of sound that can be produced by a single snap.

MOLLY: To put that in context, that is basically equivalent to a jet plane.

ROBERT: Whoa!

MOLLY: From just one snap.

MICHEL VERSLUIS: But it's very impulsive. So it's in a very, very short duration.

MOLLY: But still, it's like one of the loudest sounds in the ocean. So Michel was like, there's probably more than snapping going on here.

MICHEL VERSLUIS: Yeah, so—so ...

MOLLY: Okay, so it was 1999.

MICHEL VERSLUIS: We got the new high speed camera in our lab.

MOLLY: And so they're like, okay, we're gonna point this camera at the shrimp ...

MICHEL VERSLUIS: ... and see what happens when this shrimp snaps its claw.

MOLLY: So they take the little shrimps and they glue screws on their butts.

ROBERT: [laughs] They glue screws on their butts.

MOLLY: Yeah, they screw them into tiny platforms in, like, a little aquarium.

MICHEL VERSLUIS: So that they were fixed in space. And that was important.

MOLLY: Because it happens in, like, a microsecond. And they need to keep it still so the camera can just focus right on the claw.

MICHEL VERSLUIS: And to do the experiment, what we needed to do was to tickle them a little bit with the paintbrush.

MOLLY: [laughs] You tickled them with a paintbrush?

MICHEL VERSLUIS: Yeah, exactly. Then they cock their claws, and then they ...

MOLLY: Snap. And then it—kssht—fires. And the camera captures the entire thing with, like, thousands of frames per second.

JAD: And did they see anything?

MOLLY: They did see something.

ROBERT: What happened?

JAD: What is it?

MOLLY: When they looked at the footage of the moment just after it snaps in super slow-mo ...

MICHEL VERSLUIS: We saw a very blurry object in front of the shrimp.

MOLLY: What—what—blurry? It was just like bloppy, blurry something?

MICHEL VERSLUIS: It was bloppy blurry, yes. [laughs] I mean, it turned out that we were sort of out of focus.

MOLLY: So they refocus the camera, they do the same thing. They tickle the shrimp, the claw snaps. And they see that when the claws snaps ...

MICHEL VERSLUIS: Ah!

MOLLY: They see this, like, bubble ...

MICHEL VERSLUIS: Bubble.

ROBERT: Ohhh!

JAD: Ohhh!

MOLLY: In front of the shrimp claw. And it turns out that it's that bubble that's causing the noise and so much undersea turmoil. [laughs] The bubble is at the root of everything.

JAD: Okay.

MOLLY: And with the high speed camera, they were sort of able to see how it all breaks down. And it sort of unfolds like this ...

MICHEL VERSLUIS: What actually happens when this claw closes is that the water that's in between these claws is squeezed out at high speed. The typical speed can be up to 60 miles per hour.

MOLLY: Like as fast as a car goes?

MICHEL VERSLUIS: Oh, yes, yes.

MOLLY: So this jet of water shoots out at, like, 60 miles per hour. And what happens is, like, behind the jet is that this, like, empty space is created, like a little void in the ocean. And all the water molecules in that space, because they're like "Ooh, look at all this room," they start to expand outwards. And essentially, they just become like a little gas bubble.

JAD: They actually change from liquid to gas?

MOLLY: Yeah, they actually go from, like, liquid is like tightly-packed molecules. And then as they spread out, they become, like, gaseous. And they create this, like, little gas bubble pocket in the middle of the huge ocean. And as they have all this space they, like, get bigger and bigger and bigger until the ocean is like, no! Like, microseconds later, the ocean starts pushing back in on this bubble. And the—all the little—the little air molecules in this bubble have nowhere to go and they're getting forced closer and closer together. And so they really want to get away from each other, all those air molecules. But you're pushing them together really hard. And since they can't get away from each other, like, the energy builds up super, super huge.

MICHEL VERSLUIS: And the pressure rises and the temperature rises.

MOLLY: Really rises.

MICHEL VERSLUIS: 5,000 degrees.

JAD: What?

MICHEL VERSLUIS: The surface of the sun is also 5,000 degrees.

MOLLY: And the gas that's inside the bubble turns to plasma. [laughs]

MICHEL VERSLUIS: And that plasma emits very short intense flash of light.

MOLLY: And then the bubble implodes.

MICHEL VERSLUIS: And then ...

MOLLY: Like a microsecond later ...

MICHEL VERSLUIS: ... it generates a shockwave. And that shockwave will basically kill or stun any prey that is nearby.

MOLLY: What?

ROBERT: Somebody from the college of exaggeration graduated this particular explanation because you—God! A teeny little animal with an enormous bubble as hot as the sun. [laughs]

JAD: Wait ...

ROBERT: And then I think "Oh, yeah. okay.

MICHEL VERSLUIS: It's fairly crazy. But it's amazing how evolution has created this kind of sonic weapon.

CHILD: So basically ...

MOLLY: Yes?

CHILD: Shrimps are, like, super awesome, because they have this claw that generates huge bubbles of heat. And it's like, don't mess with the shrimp because it's a black belt.

JAD: Wow, so it's spitting out light. And hot, hot, hot temperatures.

MOLLY: Yeah.

JAD: Does that mean that—God ...

MOLLY: I know, the sun thing is crazy.

JAD: That's crazy!

MOLLY: I feel like it should be like a Marvel character.

JAD: Totally.

ROBERT: Hmm.

JAD: Yeah, 'cause if you scaled this up, the bubble would be the size of a basketball in human scale.

MOLLY: Mm-hmm.

JAD: What could I do with a basketball of sun heat and light? I could rule the world with that. [laughs]

ROBERT: Oh my God, you could probably do a lot.

JAD: Can you imagine?

[ARCHIVE CLIP: I'll be having that cab.]

[ARCHIVE CLIP: Hey, hey, hey, hey. That last piece of cake is mine!]

MOLLY: That was—well, when my sister was hanging off the dock, she asked, like, "Can we use this to power, like, the world or something?" No. The answer was no. But the same physical processes that are involved in the shrimp bubbles, right? So like the temperature and the heat that bubbles can create, researchers became really excited about. Is there a way to harness this bubble power?

MICHEL VERSLUIS: Yes, there's also a Hollywood movie.

[ARCHIVE CLIP, Chain Reaction: I think I did it.]

[ARCHIVE CLIP, Chain Reaction: Is it stable?]

MICHEL VERSLUIS: On powerful bubbles with Keanu Reeves, I believe.

MOLLY: Really? Really?

MICHEL VERSLUIS: Yes. Yes.

[ARCHIVE CLIP, Chain Reaction: There is enough energy in this glass of water to power the city of Chicago for weeks.]

[ARCHIVE CLIP, Chain Reaction: They went too far.]

CHILD: Boom! Pwwschtwwt! Pew pew pew!

CHILD: It's like boom! [laughs]

JAD: Taken with the weap—with the weapon possibilities.

MOLLY: Yeah, my nephew got excited about this, too.

CHILD: My name's Oliver. Hi.

MOLLY: But I hate to tell you, but I don't think there are any.

JAD: You mean you can't, like, make a bigger claw?

MICHEL VERSLUIS: Uh ...

JAD: Put it on a sub?

MICHEL VERSLUIS: No. [laughs]

MOLLY: Sorry, guys.

JAD: Hmm.

ROBERT: Hmm.

MOLLY: Well, there is one thing where researchers are thinking about using bubbles—and this goes beyond the shrimp bubbles—in a way that could save lives. So when I was talking to Michel Versluis ...

MICHEL VERSLUIS: Applications ...

MOLLY: ... we're talking on the phone, and he explains all the crazy bubbly stuff. And somehow, like, in the middle of the conversation he just said, "If you think the shrimp bubbles are cool, everything we know about the shrimp bubbles, like, can also be, like, adapted to use bubbles in the body."

JAD: Oh!

MOLLY: And I was like, "What?"

JAD: Wait, wait. Bubbles in the body? Isn't that ...

ROBERT: Isn't that an embolism though?

JAD: Yeah.

MOLLY: Totally. I had the same thought. Like, when divers get the bends or when they, like, tap bubbles out of IV lines and stuff.

MICHEL VERSLUIS: But these are very, very small bubbles, smaller than red blood cells.

MOLLY: According to Versluis, they're like 1/20 the size of human hair.

MICHEL VERSLUIS: And they are completely harmless.

MOLLY: And he told me about how in Toronto—and they actually just did this for the first time in November on a patient—they're using bubbles to get across the blood-brain barrier.

JAD: Huh. What is—what exactly is the brain—blood-brain barrier? Is it cells or is it tissue?

MOLLY: Yeah, it's super, super tightly-packed cells. It sort of sits between the bloodstream and the brain. It's like this protective wall, and it keeps out all of, like, the nasty stuff, so it keeps out any, like, bacteria or viruses that would be in your bloodstream can't get past the wall to get into your brain. I kind of keep thinking of it as, like, I've never actually watched Game of Thrones except for, like, one episode, and in it there was this giant wall.

JAD: Yeah.

MOLLY: To protect civilization from sort of all the bad things, the wild things. And it was made of ice and it went up forever.

[ARCHIVE CLIP, Game of Thrones: I've never fallen before!]

MOLLY: I kind of feel like that wall in Game of Thrones is like the barrier between the rest of the body and the brain.

JAD: But—but you said it's there to protect the brain. So why would you want to punch a hole in it?

TODD MAINPRIZE: Well, you can imagine that if somebody has a brain tumor, and we want to deliver chemicals in there that we think can help fight the tumor, those chemicals the brain does not want in there.

MOLLY: So the blood-brain barrier can create problems, according to Todd Mainprize.

TODD MAINPRIZE: I'm a neurosurgeon at Sunnybrook.

MOLLY: He's part of the team in Toronto that's using this new bubble technique, and here's how it works. Okay, so say you've got a tumor on the right side of your brain right above your ear. So Mainprize and his team will stick you in a chair, and then they'll put a helmet on you.

TODD MAINPRIZE: Special helmet. This helmet has 1,024 ultrasound transducers. And we aim the 1,024, all to the same spot.

MOLLY: Right on the spot at the wall where the tumor sits just on the other side, just out of reach.

TODD MAINPRIZE: Okay, so all the ultrasound waves kind of focus at that one area. And then we inject the bubbles.

JAD: How many bubbles are in a dose?

MOLLY: Like, hundreds of thousands. So they just put an IV in your arm, and the bubbles go in, and they'll go, like, into your arm, like, over your shoulder, into your heart to your lungs back to your heart. Eventually, some of them will get up to the brain.

TODD MAINPRIZE: You know, it takes approximately 28 seconds from the time we inject the bubble into an arm vein, to by the time they start going into a brain.

MOLLY: And eventually, some of those bubbles get up to the blood-brain barrier, that wall, to the spot where that laser beam is focused, that specific spot that the tumor is sitting on the other side of. And when they cross paths with that beam ....

TODD MAINPRIZE: Ultrasound waves causes the micro bubbles to oscillate in size. They'll go big and small, big and small.

MOLLY: Big, small, big, small, big, small, big small.

TODD MAINPRIZE: Oscillate in size.

MOLLY: I think of it as like a—like a bubble dance party. So at this really specific part in the brain, and it can be smaller than, like, one millimeter by one millimeter square, all of these bubbles are dancing. And what that does is it causes the wall, that specific spot, to almost loosen. And so, like, a little, like, window of space, or a little hole is created in that wall. And if you happen to have chemotherapy in your blood—which you will, because they'll give it to you ahead of time—the minute that hole is open, the idea is the chemotherapy in your bloodstream would be able to just sort of flow through that opening and get straight to that brain tumor tissue.

JAD: So they're using sound to turn the bubbles into little dancing drill bits.

MOLLY: Yeah.

JAD: And drill through the wall.

MOLLY: Yeah.

JAD: Wow!

TODD MAINPRIZE: Now the body's a living organism. So over the next six to twelve hours, it will close those gaps. It's transient, meaning it heals itself in about six to twelve hours.

JAD: And you're saying they tried this on someone already?

MOLLY: Yeah, last November. And they think it went well. One of the things these researchers said was once you're able to open these passageways to the brain, it's not just chemo that can get in there but, like, suddenly, any type of drug you might want to send through can get through. And we've just never had access to the brain before in that way. And there's this question of, like, how will drugs interact with the brain? We kind of don't know. They've never been there before. It's like a whole new frontier.

MOLLY: You think shrimping time is done?

CHILD: Yeah.

MICHEL VERSLUIS: So I mean, it basically all boils down to the same sort of physics of bubbles that we have learned from this shrimp and that we can apply to many other applications.

MOLLY: Come on! It's dinner time.

CHILD: We're gonna put it on the radio, so you'll hear it, the people that like shrimp.

MOLLY: What if people don't like shrimp?

CHILD: Then they'll just skip it.

CHILD: I can't believe Molly's putting this on the radio.

MOLLY: Oh, I make no promises that this is going on the radio.

CHILD: Oh, yeah it is!

JAD: Molly Webster. This piece was produced by Molly and Annie McEwen.

ROBERT: With help from our guest sound designer, Jeremy Bloom. Special thanks to Kullervo Hynynen, James Bird ...

JAD: Lawrence Crum ...

ROBERT: And Elliot, Sophie, Oliver and Chrissy, all of them Websters.

[LISTENER: My name is Joseph Packard. I'm calling from Columbia, South Carolina. Radiolab is supported in part by the Alfred P. Sloan Foundation, enhancing public understanding of science and technology in the modern world more information about Sloan at www.sloan.org.]

[ANSWERING MACHINE: Message one.]

[CHRISSY WEBSTER: This is Chrissy Webster.]

[CHILD: Elliot.]

[CHILD: Oliver.]

[CHRISSY WEBSTER: And Sophie by proxy, she's at her friends' house. But we are reading the credits. Radiolab produced by ...]

[CHILD: ... Jad Abumrad.]

[CHRISSY WEBSTER: Dylan Keefe is our ...]

[CHILD: ... director of sound design.]

[CHRISSY WEBSTER: Soren Wheeler is ...]

[CHILD: ... is the senior editor. Jamie York is our senior producer.]

[CHRISSY WEBSTER: Our staff includes Simon Adler, Brenna Farrell, David Gebel, Matt Kielty, Robert Krulwich, Annie McEwen, Andy Mills, Latif Nasser, Malissa O'Donnell, Kelsey Padgett, Arianne Wack ...]

[CHILD: And Molly Webster!]

[CHILD: Molly Webster!]

[CHRISSY WEBSTER: With help from ...]

[CHILD: Alexandra Leigh Young, Stephanie Tam, Micah Loewinger. Our fact checkers are Eva Dasher and Michelle Harris. And we're serious about science.]

[ANSWERING MACHINE: End of message.]

 

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