People are really good at building homes out of everything from wood and concrete to mud and ice. But when it comes to animal homes, creatures can be more inventive than humans!

In this creatively constructed episode, Molly and cohost Marama renovate Brains On HQ with the help of some clever critter contractors. They talk to animal experts and navigate demolition disasters to build a delicious new food hall for Brains On. Plus, a super spiffy Mystery Sound!

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MARIMA: You're listening to Brains On, where we're serious about being curious.

SPEAKER: Brains On is supported in part by a grant from the National Science Foundation.

MARIMA: Whoa, what's going on around here?

MOLLY: Oh, hey, Marima. I know we're supposed to be taping an episode today, but--


MOLLY: I said, I know we're supposed to be taping an episode, but-- hold on a second. Hey, guys, could you please keep it down? Excuse me. Could you, please--



MOLLY: Oh, thank you, Marima.

MARIMA: Don't mention it, Molly. What's going on? Are you doing construction on Brains On headquarters?

MOLLY: Yes, we thought it was time we tore down this wall and made a space for everyone at HQ to relax outside. Check this out. Here's where we'll put the smoothie river, a different flavor every day. And up there is the CD zipline. You can soar over the whole park using only pasta power, and up there is where we're installing the cotton candy cloud machine.

MARIMA: Smoothies, pasta, cotton candy, I'm sensing a theme here.

MOLLY: We call it the Garden of Eatin', the ultimate indoor-outdoor cafeteria.

BARTHOLOMEW: Indoor-outdoor? I thought you said it was outdoor-indoor. This changes everything, Molly.

MARIMA: Who are you?

BARTHOLOMEW: Bartholomew Buttress Balustrade, builder and backbone of this operation. Pleased to meet you.

MOLLY: Bartholomew, indoor-outdoor doesn't sound that different from outdoor-indoor.

bartholomew: Please, they're light years apart. Next thing you're going to tell me a firefly is the same thing as a lightning bug.

MARIMA: They are.

BARTHOLOMEW: That's it. I can't work under these conditions. If you two know so much, you can do it yourself. I, Bartholomew Buttress Balustrade, quit.

MOLLY: And he's gone. And he left a huge hole in the side of Brains On headquarters.

MARIMA: Looks more outdoor than indoor to me.

MOLLY: You're listening to Brains On from APM Studios. I'm Molly Bloom, and I'm here with my co-host, Marima, from Halifax, Nova Scotia.

Hey, Marima.

MARIMA: Hi, Molly.

MOLLY: Today, we're talking about animal homes. So, Marima, are you a big animal fan?

MARIMA: Yeah, I am a big animal fan.

MOLLY: What are some of your favorite animals?

MARIMA: If I were to pick my top three favorites, my third favorite would probably be a wild horse. My second favorite, a snake.


MARIMA: And my first favorite-- wolves. Very big wolf fan.

MOLLY: Very good choices. So can you tell me why wolves are your favorite?

MARIMA: Well, one, they look so cool. And I like how they are associated with night and moon and stuff like that.


MARIMA: My name means moon goddess as well.

MOLLY: Oh, cool.

MARIMA: And I've gotten a lot of favorite animals, but I feel like this one's stuck because I live with a canine, and it probably helps me.

MOLLY: Totally. Have you ever wondered about how these animals make their homes where they live in the wild?

MARIMA: I always wondered if these specific animals have specific homes. Or if they just find somewhere cozy, they just settle in.

MOLLY: So if you were living in the woods, what animal would you want helping you to build a home?

MARIMA: I would want a fox to help me build a home because if I was doing one, on the ground there, they're really fast stickers.

MOLLY: Very cool. And what animal would you definitely not want helping you?

MARIMA: A worm, probably.


MARIMA: Because they can't really do much.

MOLLY: Too tiny. Too slimy, maybe. Marima, isn't the only one thinking about animal builders. Lots of you have been asking how different animals create their homes.

HOSA: My name is Hosa. I'm from Carbondale, Colorado. My question is, how do ants build their ant nests?

RYAN: Hello. My name is Ryan.

BRADY: Hello my name is Brady. We're from Minnesota.

RYAN: And we want to know how do spiders make their web.

DRAKE: Hi. My name is Drake. I live in Bear Valley. I saw a hornet nest on our roof, and how do they build it? Why?

MOLLY: Nature, really, has some of the most creative builders.

Did somebody say nature?

MARIMA: Is that someone on the roof about to swing with a vine rope?

SHAHLA: Ooh-aah, Ooh-aah, Ooh-aah, Ooh. Oooh-ooh-aah-aah. And that's how you do a triple twist, quadruple flip, double dip, double decker, bacon and cheese dismount.

MOLLY: Brains On editor Shahla Farzan, what are you doing here?

MARIMA: And where'd you find that Vine to swing on? There aren't even any trees for it to attach to.

SHAHLA: Oh, I always carry a backup vine. I mean, you never know when you're going to need to swing somewhere. But what was this that I was just hearing about nature? Are you trying to make your own underwear out of bark or figure out which leaf shape is the prettiest? Because it's the Sycamore tree. No question.

MARIMA: Actually, we were just trying to figure out what to do with this giant gaping hole in the side of Brains On headquarters.

SHAHLA: Oh, yeah, I like it. Indoor-outdoor living is so in right now, or is it outdoor-indoor? Hang on, wasn't this where the Garden of Eatin' was supposed to go?

MOLLY: Our builder quit over artistic differences.

SHAHLA: Bummer, I was really looking forward to that all-you-can-eat-pizza-go-round. So it sounds like you've got a construction conundrum and a whole mess of critter questions. Oh, wait, I've got an idea. How about I introduce you to some animal builders? I've met tons of them in the woods whenever I'm collecting new leaves for my leaf collection.

MARIMA: That's a great idea.

MOLLY: Wait, did you say leaf collection? I thought you collected feathers.

SHAHLA: Yeah, I figured I should branch out more. This collection is all leaves that remind me of Taylor Swift songs. This leaf is You Belong With Me, and this leaf is You Belong With Me Taylor's Version. Totally different vibes. Wait, what was I just saying?

MARIMA: You were telling us about the animal builders you know.

SHAHLA: Right. Right. Right. Lots of animals are what scientists call ecosystem engineers, which means they change the environment around them in different ways. Some animals can even build homes that are so big, they change the entire ecosystem.


SHAHLA: Wait right here. I've got someone for you to meet.

MARIMA: What's that sound?

SHAHLA: Hello. Incoming.

MOLLY: Whoa, are those wasps?

HORTENSIA: Hornets, actually. We're a type of wasp.

SHAHLA: Molly, Marima, this is my buddy Hortensia. I think the last time we saw each other was Vegas '96, right?

HORTENSIA: Oh, yeah, we were both dressed up like--


SHAHLA: Yeah. Good times. Anyway, Molly, Hortensia and her friends could really help us out here. Pretty much everything about hornet nests is designed to help raise their young and protect their queen. And these hornets have some great renovation ideas for the Garden of Eatin'. What do you think, Hortensia?

HORTENSIA: Well, the space does have good bones. I've got it. It's giving hexagons. It's giving paper mache. It's giving nest vibes. All right, everyone. Come on in. I'm going to need about 5,000 tons of wood pulp, so let's get chewing.

MARIMA: Chewing?

SHAHLA: When these hornets want to build their nests, they chew wood and mix it with their own spit to make sheets of paper-thin material. Then, they use it to build the walls and structures of their nests. It's super light and strong.

MOLLY: A house made out of spit and paper? That's a little unusual.

HORTENSIA: And where do you want the nursery? I think if we use all this vertical space, we can fit 100, maybe 200,000 babies in here, easy.

MARIMA: That's a lot of babies.

SHAHLA: Hornets use their nests like giant nurseries. They make tons of these little six-sided cells that are like cribs.

MARIMA: So does the queen lay eggs in the cribs?

SHAHLA: Yeah. So when the eggs hatch into little grubs called larvae, worker Hornets feed them and keep them warm until they grow into adults.

MARIMA: That all sounds cool. But if this whole room is filled with babies, would there be any room for the zip line or that pizza-go-round, or, you know, us?

MOLLY: That's a good point. I do love the paper thin walls. They let in so much light. But I'm not sure if Hortensia's vision is right for us. Sorry to kill your buzz, Hortensia.

HORTENSIA: You heard her. Drop your wood pulp, everyone. We're moving out.

SYNTHESIZED VOICE: Brains, Brains, , Brains On.

SHAHLA: OK, I know the hornets weren't the right fit, but don't worry. I've got another great animal builder for you to meet, someone who loves food just as much as we do and really knows their way around a picnic.

MARIMA: Army ants?

SEARGEANT ARMY: We're not army ants. We are an ant army. I'm Sergeant Ant. Now, Cadet Shahla tells me you're in need of some builders?

SHAHLA: Molly, Marima, I know the wasps weren't on your wavelength, but I think these ants could make this place something special. Ants are really good at making big, beautiful homes that use every square inch of space.

MOLLY: Yeah, they must be pretty good builders because every colony has hundreds or even thousands of ants, right?

SHAHLA: Right. And they're constantly digging tunnels, storing food, and taking care of their queen. Sergeant, you think you could help us out?

SEARGEANT ARMY: You betcha, Shahla. You've saved my thorax too many times to count, and you're the only reason I survived the Battle of the Backyard Barbecue. So anything you need, we're your ants.

MOLLY: We're just trying to build our Garden of Eatin'.

MARIMA: But now, all the construction materials are chewed up, and everything is covered in wood pulp and hornet spit. Yuck.

MOLLY: And it's a big job. No offense, but you're small.

SEARGEANT ARMY: Don't you worry, ma'am. Each of my soldiers can lift more than 50 times their weight. Easy. That's like an adult human picking up about 2 and 1/2 walruses. All right, ants, cart out that wood pulp. I want to see this place shine.

MOLLY: Wow, I like them already.

MARIMA: I thought ants lived in anthills?

SHAHLA: Oh, the ant hill is just the tip of the antburg. Ants live in massive underground cities sometimes, with tunnels reaching up to 25 miles underground.

MOLLY: Whoah, 25 miles? That's like if you buried more than 3,000 school buses in one long line underground.

MARIMA: Or more than 400 statues of liberty.

SHAHLA: Hey, Sarge, it's nice and warm near the ceiling.

SEARGEANT ARMY: Great. The kids will love it.

MARIMA: Oh, no, babies again?

SHAHLA: I know. I know. You weren't too keen on the baby hornets, but check out these awesome ant larvae. They need to be at just the right temperature. So worker ants are constantly scurrying up and down, bringing them close to the surface to get warm, then back down into the Earth to cool down.

MARIMA: I've heard about this. By warming up and cooling down the ant babies, the worker ants can control how fast they develop.

MOLLY: Yeah, I don't mind a few new ant friends, as long as they're not taking up the whole space with cribs. It's OK by me.

SEARGEANT ARMY: All right, soldiers, that's enough clean up. Start doing toil and hull and soil.


SEARGEANT ARMY: Once we get a few thousand pounds of dirt in here, we can get started on those tunnels for you. We'll have to make them human-sized, I guess. How tall are you? Say, 300 ant lengths?

MOLLY: Whoa. Whoa. Whoa. Whoa. Wait a minute. Sergeant Ant, we already have a basement. We don't need you to build tunnels.

MARIMA: Or to bury us alive. I don't think this is what Molly meant when she said she wanted to get outside.

SEARGEANT ARMY: So let me get this straight. You don't want a nice cozy anthill to stay in?

MOLLY: No, sorry.

SEARGEANT ARMY: You want to be outside, exposed to the elements? The enemy?

MOLLY: That's a weird way to put it, but, yes, I guess?

SEARGEANT ARMY: I don't know anything about indoor-outdoor living or outdoor-indoor living. You'll need to find another animal builder to help you with that.

SEARGEANT ARMY: Ten-hut. Ants, let's roll out.

MARIMA: At least they helped clean up our wood pulp spit situation. So we're back where we started.

MOLLY: Before any other messes get made, let's take a quick break for the--

SPEAKER 2: Mystery Sound.

MOLLY: Are you ready to hear the mystery sound?


MOLLY: OK, here it is.


OK, I do not know what this is. You and I are in the same place here. So what do you think it is?

MARIMA: I think, one, it sounds a bit like, either like a bee or a fly. And it's like buzzing with that, or it's like that, but really loud.


MARIMA: But it also sounds like when you're reeling in a fishing pole?

MOLLY: Yes, that is where my brain went to. Yeah, like the cranking of the little reel. Have you ever been fishing?

MARIMA: Yeah, I've been fishing quite a few times, and I don't catch things very often.

MOLLY: Is it fun? Do you recommend it? Should I try it?

MARIMA: Yeah, it is fun.


MARIMA: But just don't expect to catch anything.

MOLLY: So if you're not catching fish, what do you enjoy about fishing?

MARIMA: I honestly just enjoy the thrill of like when you realize you've got something, and then just like looking at what you got, and then, of course, you have to-- well, unless you're fishing for dinner or something. But you do have to throw it back in the water. But it's just fun to see what kind of fish it is and reel it in.

MOLLY: So that reeling in sound is one that is exciting to you? So maybe, I bet, you're right. OK, well, we'll listen to it again. Get another chance to guess and hear the answer after the credits.

Hi, friends. We're working on an episode about why we're sometimes afraid of the dark. But the dark is also totally cool. So we want to know. What do you love about the dark? Does it feel mysterious, exciting? Do you like telling stories around a campfire?

Are you a night owl? Do you think nocturnal animals, like possums, are awesome? We want to hear from you. Record yourself describing what you love about the dark, and send it to us at While you're there, you can also send us mystery sounds, drawings, high fives, and questions.

MARIMA: Like this one.

ELLIS: Hi. My name is Ellis, and I'm from New Orleans. My question is, do flies ever blink?

MARIMA: You could find an answer to that question on our Moment of Um podcast. It's a daily dose of facts and curiosity you can find wherever you listen to Brains On. Again, that's

MARIMA: Keep listening.

You're listening to Brains On from APM Studios. I'm Marima.

MOLLY: And I'm Molly. Brains On pal, Shahla Farzan, has been trying to help us find an animal builder to create the Garden of Eatin' Cafeteria at Brains On headquarters, but we keep running into problems.

MARIMA: The hornets had too many babies.

MOLLY: And the ants wanted to bury us in 5,000 pounds of dirt.

SHAHLA: Well, you're in luck because I've got another candidate. Guys, meet webster.

MARIMA: Ah, a spider.

WEBSTER: Ah, a human. See how that sounds? Pretty rude, I'd say.

MARIMA: Oh, sorry, Webster.

SHAHLA: Spiders might look different from us, but they're not out to hurt you. Webster and I go way back, ever since we were in that Swedish hair metal band.

MOLLY: Oh, you mean Black Widow? You guys rocked.

WEBSTER: Black Widow. Those were the days.

SHAHLA: I know. What I wouldn't give to be a tour bus full of spiders right now. Anyway, spiders are master builders, using light, strong silk to craft their webs. They also don't live in colonies, like ants or wasps. Most live alone. And their webby home is also their greatest strength for catching lunch.

WEBSTER: I'm not here to hurt humans, just snag some sweet, sweet bugs, and help you build your Garden of Eatin'.

MARIMA: So how do spiders build their webs anyway?

SHAHLA: Oh, I was just talking to Mark Milne about this. He's a spider scientist at the University of Indianapolis. And he told me that spiders start their building process by picking a good-looking leaf or branch close to a food source.

MARK: And so once they find that nice spot to start building a web, they'll sit on a location near there, and then they'll send out a string of silk.

SHAHLA: Once that silk snags on something else, the spider has a line. From there, they can build their whole web. They send out more silk strings, which catch on other sticks or leaves, until they have a whole network of silk.

MARK: So basically, these strands of silk interconnecting and crossing each other, they can then build the circles, concentric circles, getting smaller and smaller and smaller. Usually, it's actually the opposite of small to large.

MARIMA: Where does this all come from?

WEBSTER: From my butt, of course, or my abdomen, if you want to get technical. It starts as a liquid, which turns into a solid, when it hits the air.

MOLLY: I mean, I love butt silk as much as the next person, but are you sure it's strong enough? We're building a pasta-powered zipline, remember? I don't want people crash landing in the middle of the ice cream lagoon.

SHAHLA: Sure, it is. Even though spider silk is incredibly thin, it's actually five times stronger than steel. In fact, some scientists have already made artificial spider silk. That could be used in everything, from parachutes to bike helmets.

WEBSTER: Not only is it strong, if you hire me, I can guarantee a Garden of Eatin' will have the freshest food anywhere. Once I lay down my sticky adhesive, it'll be an all you can eat bug buffet.

MARIMA: Tasty, but not quite what I had in mind. I might just stick to cotton candy and smoothies.

MOLLY: Yeah, if we cover everything in here with sticky webs, won't we stick to everything?

WEBSTER: Of course, not. All you have to do is just walk around using the tiny claws on the bottom of your feet, like us spiders.

MOLLY: Webster, we don't have tiny claws on our feet.

WEBSTER: Really? Are you sure? Like, did you even check?

MARIMA: No claws, just fingers and toes.

WEBSTER: Oh, well, that could be a problem.

MOLLY: Sorry, Webster, I don't know if you're the right fit to build the garden for us.

MARIMA: Yeah, I don't want to get stuck trying to get a snack.

WEBSTER: Oh, well, my mom always told me to stick to what I know. And wouldn't you know it, what I know is being sticky. See you around.

MOLLY: Shahla, we've met three animal builders already, and were no closer to the Garden of Eatin'.

MARIMA: I've been dreaming of that smoothie river. We have to make it happen.

SHAHLA: That's it. A river. Of course, why didn't I think of it before? Molly, Marima, I've got someone for you to meet. Sigourney-- Sigourney Beaver.

MOLLY: Sigourney Beaver?

MARIMA: The actor?

SIGOURNEY: Not so loud. Just call me Sigourney. I retired a long time ago so I could pursue my true passion, building dams, lots of dams.

SHAHLA: Beavers change their entire ecosystem by building dams, you know, that big wall-like structure made of sticks and logs that sits in a body of water. Sometimes, these can even block the flow of a river, creating deep ponds around them.

MOLLY: That's actually exactly what we want. I thought it would be so nice to have the ice cream lagoon over there in that corner.

SIGOURNEY: Oh, we don't have to worry about keeping it in one little corner. Why not a whole ice cream lake?

MARIMA: I like the sound of that.

SHAHLA: Oh, yeah, Sigourney and her beaver buds are all about making ponds. You know, my friend, Emily Fairfax could probably help me explain. She's an environmental science professor at California State University Channel Islands, who specializes in beaver builders. She told me beavers like to build dams that create ponds because they're pretty awkward on land.

EMILY: They are large, 40 to 100 pounds, shaped like a bowling ball. They've got a big paddle tail coming out of the back end, webbed back feet, and then grabby little hands. And so when they walk across the land, it's truly more of a waddle. They're really ungainly and which makes it easy for predators to hunt them when they're out on the land.

SHAHLA: So beavers chew down trees and use them to make a dam across the stream. This creates a pond, where the beavers can stay underwater and out of sight of predators.

SIGOURNEY: We're much more graceful in the water.

MARIMA: So cool. Do you think you could throw in a couple of beaver lodges? They look like great big piles of sticks, but inside their rooms, they keep you cool in the summer and warm in the winter.

SIGOURNEY: Absolutely. We can build you a couple lodges, right next to the ice cream lagoon. Instant cabanas.

SHAHLA: And that's not all. Emily told me that beaver dams and beaver lodges actually help our environment.

EMILY: So when beavers make their wetlands, they slow down, and they store a ton of water.

SHAHLA: So by blocking the flow of a stream or river, beaver dams can create these lush wetlands. And if a fire breaks out, the wetland is like a natural fire break. All that water stops the fire in its tracks.

MARIMA: So beavers are like nature's firefighters.

SIGOURNEY: And let me tell you, me and my crew, we never take a break. Every day, we're digging. We're cutting down trees, slapping mud on walls, reinforcing dams. You get built-in maintenance for life.

MOLLY: I mean, out of all the animal houses we've heard about, so far, this might be the best inspiration for the Garden of Eatin', but it's still not quite right.

MARIMA: Molly, you like the beaver pond, right? And didn't you also like the paper walls the hornets used to build their nests?

MOLLY: Yeah, it was the perfect material. Strong enough to keep out the rain, but it lets in a lot of light, too.

SHAHLA: And I don't know about you, but I could go for a few of those ant tunnels in the Garden of Eatin'. I'm running out of air vents to explore an HQ.

MARIMA: Yeah, those tunnels are pretty cool, and I bet, Webster's super strong spider silk will come in handy. We can make a spider web climbing gym.

MOLLY: I love that idea.

MARIMA: All right, animal buddies, let's get to work

MOLLY: Animals are pretty incredible builders.

MARIMA: They make all kinds of different homes to keep themselves safe, escape from things that want to eat them, and raise their young.

MOLLY: So whether they build paper nests--

MARIMA: Underground cities--

MOLLY: Sticky webs--

MARIMA: Or even wooden dams and lodges, even the smallest animal homes can have a big impact.

MOLLY: That's it for this episode of Brains On.

MARIMA: This episode was produced by Molly Quinlan, Rosie DuPont, Molly Bloom, Anna Goldfield, Aaron Waldeslassi, Anna Wegel, Nico Gonzalez Wisler, Ruby Guthrie, and Marc Sanchez.

MOLLY: Our editors are Sanden Totten and Shahla Farzan, sound design by Marc Sanchez. And we had engineering help from Alex Simpson and Josh Kelly. Beth Perlman is our executive producer. The executives in charge of APM Studios are Chandra Kavati, Alex Schaffert, and Joanne Griffith. Special thanks to Kate Epstein, Andy Doucette, and Erica Romero.

MARIMA: Brains On is a non-profit public radio program.

MOLLY: There are lots of ways to support the show. Head to

MARIMA: While you're there, you can send us mystery sounds, drawings, and questions.

MOLLY: And you can subscribe to our Smarty Pass, gives you a special ticket to Brains On Universe bonus content plus ad-free episodes.

OK, Marima, are you ready to hear the mystery sound again?

MARIMA: I think so.

MOLLY: OK, here it is.


All right, any new thoughts?

MARIMA: That time it made my teeth hurt a little.

MOLLY: Sorry about that.

MARIMA: I still think it's either like an insect buzzing or a fishing pole reeling in.

MOLLY: OK, I think those are great guesses. Let's hear the answer.

ANAIS: My name is Anais, and I'm from Austin Texas. And that was the sound of a spoon against dried ice.

MARIMA: Dried ice?

MOLLY: What in the world.

MARIMA: I don't even know what dried ice is.

MOLLY: Wow. It's like a block of dried frozen CO2?

MARIMA: And that's supposed to make the same sound as a fishing pole reeling in?

MOLLY: Apparently. OK, that was a very tricky one.


MOLLY: Thank you so much. And now we know if we ever need to make a movie, and we don't have a fishing reel handy, and we need a sound effect of a fishing reel, we'll just get a block of dry ice because that's easier, right?


MOLLY: Yeah.

MARIMA: And a spoon.

MOLLY: Totally. All right, we got a plan.


Now it's time for the Brains Honor Roll. These are the kids who keep the show going with their mystery sounds, drawings, questions, and ideas.


We'll be back next week with more answers to your questions.

MARIMA: Thanks for listening.

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