Radiolab - Baby Shark

Episode Date: June 20, 2025

This is episode five of Swimming with Shadows: A Radiolab Week of Sharks.Today, the strange, squirmy magic behind how sharks make more sharks. Drills. Drama. Death. Even a coliseum of baby sharks duking it out inside mom’s womb. And a man on a small island in the Mediterranean trying, against all odds, to give baby sharks a chance in a little plastic aquarium in his living room. Can a human raise a shark? And if so, what good is that for sharks? And for us? Doo doo doo doo doo doo.Special thanks to Jaime Penadés Suay and la Fundación Azul Marino.EPISODE CREDITS: Reported by - Rachael CusickProduced by - Rachael Cusickwith mixing help from - Jeremy BloomFact-checking by - Diane Kellyand Edited by  - Pat WaltersEPISODE CITATIONS:Articles - Claudia’s original reporting that inspired the episodeSignup for our newsletter!! It includes short essays, recommendations, and details about other ways to interact with the show. Sign up (https://radiolab.org/newsletter)!Radiolab is supported by listeners like you. Support Radiolab by becoming a member of The Lab (https://members.radiolab.org/) today.Follow our show on Instagram, Twitter and Facebook @radiolab, and share your thoughts with us by emailing [e-mail] support for Radiolab’s science programming is provided by the Gordon and Betty Moore Foundation, Science Sandbox, a Simons Foundation Initiative, and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.

Oh wait, you're listening? Okay. Alright. Okay. Alright. You are listening to Radiolab. Radiolab. From WNYC.

See? Yep. Lulu. Latif. Radiolab. Day five of our week of sharks. Back with our lead reporter slash lifeguard, Rachel Cusick. Hello, hello.

Wait, Rach, is this like our, this is our end of week of shark? This is the end of the week of shark, the final day, the final business day. The final business day of sharks. You might have some sharks in your weekend, but we won't be responsible for them. So today I want to end the week by circling back to the very beginning, which is to say, baby sharks. You can't even say the word without it. Without a doot-doot-doot.

I wanted to know, like, you two both have little humans. Do you hate that song? Do you listen to it daily? What's your relationship to that song? When did the song come out? 2015, the Korean one came out. Yes. So we had kids after that.

And by that point, I knew that this was sort of weapons grade song. So we kept it out of the house. Wow, it's like a zombie apocalypse. You're like, don't open the doors. That's right. Baby shark's coming. We'd seen other people go through it

and we're like, it's not gonna happen here. I don't have children, but it seeps into you, just being in the world. It does. It swept the world. It is everywhere. Yeah, so everyone has the same feeling about it. But then I was like, wait, what are baby sharks like? Like, how do baby sharks get born? How do baby sharks get born? Yeah, like, do you have an idea of what shark birth looks like?

I mean... Man, I don't know. Well, like, do you have an idea of, like, what shark birth looks like? I mean... Man, I don't know. Well, like, they are really fishy. Like, you think they do have eggs? But like, I want them to have labor. Yeah, so I found someone to answer this question for me. I've always been, like, an ocean nerd, but... Science reporter Claudia Geib, who, like most of the people we've had on this week, is a

bit of a shark fangirl. So by the time I got to this story, I was definitely fully a crazy shark lady. I actually ran into her work because of an amazing article she wrote about baby sharks. And she kind of just introduced me to the very wacky world of shark reproduction. And I want to share it with you because it's just so fun.

Okay. So the first category of shark birth is... Let me just make sure I get the term correct. Gotta look back. Yes, okay. So we have viviparas. My name is Teeny Meeny Miny Moe. Ooh.

I'm viviparous. Like in vivo? Yeah, exactly. Viviparous sharks give birth to live young, just like humans or like other mammals. Just like you and me and dolphins. The embryo develops in the mother's womb. They have a womb, there's a placenta.

Some of them even make this sort of milk, essentially like secrete a type of milk into the womb. Like a little milk bath for babies? Yeah, they're in a little milk bath. So they're just like fully pregnant and- They come out like little baby versions of the larger shark. Like how big? It depends on the shark.

So white sharks come out like three or four feet long. Whoa. That's huge. That is enormous. But I mean, there's other sharks that come out like the size of your pointer finger. Cute. I'm not a grand one pixie troll very-

No, no, no. And like God bless the hammerhead shark mothers. Yes, yes, yes. Oh, that's cool. That was just me hoping it would be so hard to make it work. Yeah, so that's the first category. Okay. And then moving on to category two, which is...

Ovovivi Paris. Ovoviviparity. Okay. So it's like a live birth, but also eggs. My baby's tingling me right now. A live birth, but also eggs. Yeah, what does that mean? So the embryo actually forms inside of an egg case,

but that egg case hatches still inside mom, and then the baby comes out. So it kind of is combining the strengths of a live birth where you're protecting the young inside you, but it happens a lot quicker and the sharks can make a bunch more eggs. There's one whale shark that was found and it had 300 whale sharks inside it.

Wow. And then there's sharks that can fertilize sperm from multiple fathers. So they kind of place bets on different sharks, baby daddies. Okay. So they're just kind of like taking it all in, they're like, we'll consider your offer, and then they just like, just dole it out. That's a new take on take it all in.

I think one of the nutsest of all nuts shark reproduction stories is the sand tiger shark. Okay. Okay. They create a bunch of eggs. And the process that this shark has developed to get big and strong in the womb is to eat its brothers and sisters. What? It's like the coliseum for baby sharks.

It is a gladiatorial match in mom's womb. Inside the shark. Inside the shark. So you'll see scientific papers where there's like a uterus that's been sliced open and there's just like one shark and then a bunch of empty egg cases and it's like, I ate those. So okay, so that's the Ovo Ovi Parodi. And then the final category. Ovi Paros are just the plain old egg laying sharks.

So the mom puts an embryo inside the sort of egg case thing and then she just releases all of those eggs into the ocean. It's feeding on a yolk sac just like a chicken and it has everything it needs inside this little egg case. So the mom will only do like one or two of these at a time and they look like these little envelopes. You can sometimes see them wash up on the beach. Oh yeah dude! Oh my god the mermaid purse thing. What's the mermaid's purse thing? It almost looks like two boomerangs back to back. Yeah, but there's also a shark that lays an egg case that's shaped like a spiral drill.

So it like screws itself into the rock kind of thing. So that nobody comes along and eats it because they're out there hanging out in the ocean by themselves. And those egg laying sharks, those are the sharks that we are going to talk about today. That's where the story that Claudia had written about begins. Oh, cool. This wasn't even the story.

That was the warm-up. That was just so funny. I'm sorry. I love it. And it was just too Willy Wonka, like, come with me in the world of pure imagination. And they're crazy little characters, you know, what they do. And so this story is one man's possibly Sisyphean, but definitely sublime attempt to maybe just slightly rejigger the balance between humans and sharks. Mm-hmm.

Yeah, yeah. Can I just ask you to introduce yourself, say who you are, and yeah, what you do? Hi, my name is Greg Noll. What I actually do or what I do when I do? Greg has taught English as a second language. He's done quality checks on electrical circuit boards. But his life's work, I think he would say, is the shark conservation and education organization that he founded.

Called Shark Club Malta. Which is in Malta. And where is Malta again? Little island below Sicily. Warm, Mediterranean. And it's just a really beautiful place to be. And so you were just interested in sharks because you loved being in the ocean or like what was it about sharks that interested you in the first place?

They were just kind of fascinating. They were very kind of mysterious. So I thought, okay, let's learn more about them. But when Greg moved down to Malta from Britain, this was in 2007, he pretty quickly realized... There was nobody really in Malta focusing on sharks, doing anything about sharks. There wasn't a national aquarium at the time, and there weren't even many sharks in the waters near Malta where you could scuba dive. So that was why I first started going to the fish market.

He wanted to learn about sharks so badly, he was just willing to go look at them in buckets. Yeah, I guess it's kind of strange, but it was kind of like, well, if I want to learn something about sharks, I need to go and find where I can see them. So Greg would get up early, early in the morning, head down to the coastline where this fish market was. It was in this old rickety building. And he'd start talking to the fishermen,

saying like, I don't know, you got any sharks? You mind if I check them out? Yeah, yeah. And so he'd go back, see these bins filled with ice and dead sharks, he started measuring the sharks. With my tape measure and my camera taking pictures. Photographing them. Learning more and more about the different species

of sharks around Malta. Learning about the basics of their anatomy. Checking whether it's male or female. Just gathering basic information for this organization that he was setting up. Sometimes recover certain parts of sharks from bins. Like, I'll grab a jaw and I'll clean it up and I'll use it as a demonstration that I'll give at

a community fair when I'm teaching people about sharks. Wow. But a couple of years into his fish market research, things started to get a little interesting for Greg. Wow. But a couple years into his fish market research, things started to get a little interesting for Greg. Yeah. One day in 2011, Greg's at the market doing his thing and he sees this small spotted cat shark. A small spotty little shark. Just kind of inspects it like he always does. But then he just like notices something coming out of the small spotted cat shark. Oh what's that? What's that thing protruding? It's these tiny curly strings. These fibrous tendrils. Popping out of the shark's cloaca,

which is like a shark vagina. Greg bends down. Kind of carefully took hold of him. At this point the fishermen nearby are just like giving him the side eye. Well listen, there was a few kind of like craned necks looking across. So what's like, what's he doing? But he just starts to pull on it. Slowly pulled and pulled and pulled. And out came this perfect little four, four and a half centimeter capsule with curly tendrils at the top, curly tendrils at the bottom.

Huh. And he's like, oh, this is a shark egg. So is it almost like a ravioli? Let's imagine like a half ravioli. Like a two inch by one inch rectangle. Pale greenish color, almost transparent. And he holds it up to the light and he sees this little bulge. Inside the ravioli shape capsule. So here he is holding this little ravioli

in the middle of the fish market. What do I do now? Is it dead? He doesn't know. So it came out of a dead shark. Right. It could be dead but it could maybe be alive. Just kind of thinking, or at least we could learn something from it. So I took it back home. But it in a little plastic aquarium that he had. The kind of thing that kids would have sometimes. So that was never actually used, just happened to be kicking around the house.

So then I'm thinking about, okay, obviously the shark would lay the egg in the sea, so I'll go and collect some seawater. With like a bucket? Yeah, just literally a bucket, take it back home. Dumps the ocean water into this little aquarium. With a little air pump just to keep the water oxygenated. Dangle a piece of string across the width of the aquarium. With a little air pump just to keep the water oxygenated.

Dangle a piece of string across the width of the aquarium. Why? Just to replicate some seagrass or something that the egg would hook onto. So he hooks the little ravioli tendrils onto the string and suspends it in the floating water. And then wait. Because I mean once you put it in there what do you do? Apart from watch it every day or several times a day or many, many times a day? Every time you walk past it, you take a

look to just see what's going on. It just became a little bit like a magnet. Day one, day two. Every time I was in and out moving past it, take a look, take a look, take a look. Day four, five, six, seven, nothing happening. And after around about three weeks, you notice the little bump on the top right hand side of it. So now each time I'm walking past, I'm now focusing on the little bump.

And the little bump slowly separates from the main yolk section itself with a tiny, tiny, almost thread-like connection. And it starts to move. Hmm, nope. Just kind of like wiggling a little bit. And it's like, oh my gosh. This shark, this baby shark that I brought home.

A dead shark, a dead shark. Is still alive. Now I should say Greg is standing, if somewhat amateurishly, on a sort of scientific frontier. I mean, sharks had been bred in captivity and eggs had hatched in aquariums, but... The thing that had never been done before was taking an egg from a dead shark... And getting it to... Develop. Nobody had ever done that.

Nobody. So this was a first. And now he's thinking maybe, maybe I could even get this thing to hatch. Which is what Greg is going to try to do right after this short break. Radio Lab Sharks. We're back. All right. We pick up with the story of Greg with his little egg case in his little kid plastic aquarium and the egg case has a bump which has just begun moving.

An egg case that Greg at this this point, has decided to name. Squiggle. I was squiggling in the egg case and I didn't know what else to call it. It's like, it's squiggling around. That's how I described it to people. And now that he knew that it was alive and he'd given it a name. Now I'm thinking, maybe I need to actually get a slightly bigger aquarium and something a little bit, I would say, more professional, you know, made of glass instead of plastic.

So he moved Squiggle into his happier, newer home. And so now we're like six weeks, seven weeks, eight weeks. Squiggle is growing and moving more and more. It's still this sort of lump that's attached to a yolk in a thin thread. And then... The yolk itself starts to appear to have blood vessels form on it.

So you almost see like vein-like structures on the yolk sac. What? And they kind of snake their way up the yolk sac to this little placental connection, which then in turn is going into the shark. Like blood? Yes. So it's blood going to the head of the shark. That is wild.

Yes. It is alien-like because it has no distinctive shape distinctive shape doesn't have the distinctive snout. There are no fins It's I don't know. How would you describe it? It's just like a little Something so you'd walk by squiggle like a couple times a day What's up? I wasn't necessarily talking to squiggle, but when people said how's it doing? How's it doing? So I squiggle squiggles doing fine and then one day it just simply stopped moving It squiggle stopped squiggling.

Oh no. And it just never started again. That was the end of Squiggle. But Squiggle left behind this little bit of hope for Greg. This beautiful little piece of ravioli kind of proved it was possible. So there was this kind of, this drive. So Greg heads back to the fish market, tries to get as many eggs as he can. Not even like pulling out the strings when he sees them.

He now just starts cutting into the dead sharks. Whoa! The fishermen are just letting him do this? Well, Greg got very good at spotting which sharks had egg cases in them. But also these fishermen... They were curious too. To the point where we arrived, they now tell us, oh, I've got some of this and I've got some of this. And at this point, he has egg cases upon egg cases at home. Multiple aquariums, et cetera.

And they're all starting to move. And they do a little bit of wiggling, just like Squiggle did. Going good, going good, everything's going good. But then, just like Squiggle, they would all die. And Greg is like, what's happening? Why do they suddenly stop developing? So he starts tinkering with a couple things,

like the aeration, the salinity. And then eventually he starts to drop the temperature of the tank. Lowering the temperature, lowering the temperature, lowering the temperature. And lo and behold. This mortality suddenly stopped massively. These eggs start surviving.

Everything seemed to continue to develop. Past the day that Squiggle died. Slowly get bigger, bigger, bigger, wiggle, wiggle, wiggle. And then some weeks in, he notices that one of the embryos in the egg cases starting to look like a shark. The fins developed. Seems to have a tail and a head.

It's now starting to go into a position where it has its head at the bottom part of the head case and the body is looped over to the top and the tail is now next to the head. And then one day he's cleaning the tank and he accidentally bumps into the string that's holding the tendrils and then all of the sudden all movement stops. I've just killed it. And then after a minute or so. Oh no, it's all right, it's all right, it's all good, it's all good. And then it started wiggling again. It's this defense mechanism these little egg cases have to protect themselves from predators who want to eat them.

Now at this point the little shark bodies, they're curled around the yolk sack. And Greg can see that that yolk sack is getting smaller and smaller and smaller and smaller and smaller. And after around about five and a half, coming up towards six months, that yolk sack has almost disappeared. And so he starts thinking, I bet when that yolk sack goes away, that's when this thing's going to hatch. Now, every time you go past the aquarium, you're looking, looking, looking.

Can you see any yolk? Can you see any yolk? And then one day... Oh, it's gone. And in the place where the shark used to attach to the yolk sac, there's just a little... Belly button. Literally, because it's like a presentable connection. So you could actually quite happily say that sharks have belly buttons. And at that point, the shark is ready to be born.

Wow, the belly button is the final touch, the master stroke. It is, it is, it is. So he's just sitting there, waiting for the shark to finally break out of this egg case. You can only spend so many hours with your eyes open watching a shark waiting for it to hatch. It's like the kettle, yeah?

You go to bed, you think, okay, well, everything seems fine. But then one morning, he wakes up. And there's a little baby shark sitting at the bottom of the tank. Just sitting on the bottom. Like a picture perfect miniature version of a small spotted cat shark. Just sitting on the bottom of the tank. Yeah, yeah. He did it. Yeah, he has a baby shark in his aquarium that came from a dead mother shark.

Yeah. Wow. And so this baby shark is just sitting at the bottom of the tank. And he's like, I guess it's time to let it go. Release it into the sea. Back to the ocean. So one afternoon. A group of us, I think it was seven or eight members of the organization.

They pack it up into a cooler and they drive to the north side of the island. We get our wetsuits on, put our scuba gear on, transfer the shark into the box. Just like a little Tupperware, you'd put your lunch in. Everyone got cameras, yeah, yeah, got cameras. Are the batteries charged? Yeah, yeah, yeah, the battery's charged. Okay, are we ready? We're ready. Let's get in the water.

So, they walk out into the water, dip down under, and start to dive. To a depth of, I don't know, maybe about 10, 12 meters. And they're swimming around the bottom, looking for a good place to leave this baby shark. Underwater, with a little box, a little baby shark. You can see the beaming smiles behind the regulators. And the reality of what they're doing and what they've done, it starts to sink in. The amount of time, energy, effort, dedication, concern, worry built up over the year or so of development and then hatching and releasing. They're all just tearing up, like their masks

just fill up with their tears. Seriously, it was just super, super, super emotional. So when it came to this final kind of like, now we're going to open the box and take the lid off and see what happens. Greg's holding this little box and he starts to open it. Just very slowly, slowly take off the lid of the box and the little shark wiggles around a bit. And then it kind of lifts off the box and starts to swim. I don't know there was just kind of, I don't know, there was just a very very kind of like emotional but peaceful moment. It felt like many minutes but it probably

wasn't. The shark had disappeared. We weren't going to chase it. We had no idea where it was going to go next. That shark was the first, but it wasn't the last. The total number of sharks we've released to date is 371. Whoa! And one thing that science reporter Claudia Geib from the beginning pointed out is that Greg had started this project in 2011 and I was reporting this in I think 2020-2021. So he'd by then been doing it for almost a decade.

He had published a paper on it in 2018 that essentially was like a how-to guide for taking egg cases and raising them to be re-released in the wild. And now there are other scientists in other parts of the world rescuing egg cases from these dead sharks. So it wasn't a question of, wow, we're stopping a species from becoming extinct.

It was a question of putting them back where they belong. Let's let nature take its course. And if nature determines that this creature will have a long and happy, fruitful life, fantastic. If nature says something different, it's nature doing what nature does. I hate to say it. they're going to die. That's nature, red, raw, and tooth and claw. When I was reporting this story and I spoke to this one prestigious researcher. Nick Delvey, professor in conservation biology at Simon Fraser University in Vancouver.

And in his view, it's almost kind of pointless to put baby sharks back into the ocean. He says like these babies are just like a snack for another fish. This is probably the most important, least well understood fact in marine conservation, that you should conserve the adults and not the babies. Nick says just like put this all in a different context, just imagine you're a farmer. You want to start an apple farm. I'm going to give you a choice. Would you like 10 mature apple trees or would you like 10 apple pips from my apple? And everybody when they see it they're

like oh yeah of course yeah of course give me the adults because they can breed multiple times right from the get-go. Focusing on the babies instead of the adults. It's not only a waste of time, but also kind of a distraction away from conservation efforts. Fisheries management or bycatch mitigation. That do make a big difference. These kind of activities are described as what are called feel-good conservation. These are an action that make people feel like they're helping to save the planet but they don't have a real impact.

Hmm. I had a similar question. I don't know. The more I talked to Claudia, the more I think they do do something, just a different kind of something. One piece we didn't talk about is everybody spoke about how the people around them and their community responded to this project really, really positively. And even beyond Greg's community, you know, there's even a classroom in Spain now.

My name is Jaime Penedes. I'm a biologist from Spain. Using Greg's methods. My name is Inma Gil. I'm 15 years old. To raise baby sharks. So instead of having like butterflies, you would have a baby shark in your classroom.

My name is Ignacio and I'm 16. Paola and I am 17 years old. I'm 14 years old. And in a way, it's not what's happening inside those shark tanks that matters. It's what's happening inside those kids. Honestly, I was like, concerned about how are we like going to take care of them. I used to think of sharks as like mainly dangerous.

At first I thought of sharks as big and scary creatures and now that I've been taking care of five of them, I'm pretty much relaxed. People have been taught to fear sharks. Chris Lowe, again, our shark scientist from the very beginning of this week. So the cool thing for me is if we've taught people to fear sharks, we can also un-teach them to fear sharks, to appreciate the animal. The wonder of the complexity of their lives and the complexity of their biology.

You know, we need to change our concept. Get away from the monster image. They're not monsters at all. Butterflies or sharks? Sharks. Definitely sharks. They are more interesting. Yeah, same here. I think I would prefer sharks over butterflies. Well, that is a wrap for our week of sharks. Big giant whale shark size thank you to Rachel Cusick for bringing this wild idea to us

and doing dozens of interviews to bring it to life. Thanks also to our editorial ground control, Pat Walters, for wrangling so many sharks. This episode was reported and produced by Rachel Cusick, edited by Pat Walters, fact checked by Diane Kelly, with mixing help from Jeremy Bloom, and original music by Alan Gavinski. And if somehow you are still yearning for even more shark stories going into the weekend. Terrestrials, our kids' show hosted by Lulu, has such a beautiful episode on the Greenland shark, which is the oldest of sharks. Like, the individuals live impossibly long. It's pretty neat. You can go find that on the Radiolab for kids feed. The episode

is called The Sea Troll. And one more thing, we want to give a huge thanks to everyone who supports Radiolab, especially right now. Everyone who's a part of the lab, our membership program, your support makes big projects like this possible, and we are so grateful. And if you aren't a member yet, or are thinking about giving more, this is the perfect time to take the plunge. Because if you join or re-up now, you will receive a really cool gift. A limited edition Week of Sharks hat designed by the awesome Maine-based artist and surfer Ty Williams. It's so beautiful and fun and it gives you a chance to show the world you support public

radio in the form of Radiolab. It's available to everyone who joins the lab this month, even for as little as seven bucks a month. You can join at radiolab.org slash join existing members, check your email for details and thank you so much. All right. That is really it. We're stalling. I don't want to end this thing. It's been so fun. But have a great weekend. Stay equal parts open and curious as you are wary of the shadows in the water and beyond.

Duh duh. Hi, I'm Michelle and I'm from Richardson, Texas. And here are our staff credits. Radio Lab was created by Jad Appelmrod and is edited by Thorin Wheeler, Lulu Miller and Lata Nasser are our co-hosts. Dylan Keith is our Director of Sound Design. Our staff includes Simon Adler, Jeremy Bloom, Becca Bresler, W. Harry Fortuna, David Gable,

Rebecca Lack, Maria Paz Gutierrez, Sandu Niana Sambandhan, Matt Keelty, Annie McEwen, Alec Neeson, Sarah Carrey, Sarah Sandbach, Anisa Vitte, Arianne Wack, Pat Walters, Molly Webster, Jessica Yuck, with help from Rebecca Rand. Our fact checkers are Diane Kelly, Emily Krieger, Anna Pujol-Mazzini, and Natalie Middleton. Hi, my name is Anna and I'm calling from Summerville, Massachusetts. Leadership support

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