Ants and spiders are able to defy gravity -- but how do they do it? We'll learn about how awesome their feet are and how one predator takes advantage of these powers. Plus: A very challenging mystery sound and a Moment of Um that answers the question, "How do bananas ripen other fruit?"
For more ant amazingness, listen to this episode: Ant’s: Who’s in charge here?
For more spectacular spiders, listen to this episode: Spider sense
And a vital report from the Ant News Network:
SPOILER ALERT: To see what that mystery sound is all about, click here.
Audio Transcript
Download transcript (PDF)
NARRATOR 1: You're listening to Brains On, where we're serious about being curious.
NARRATOR 2: Brains On is supported in part by a grant from the National Science Foundation.
SANDEN TOTTEN: I'm Ant and you're listening to the Ant News Network coming up picnics where are they and how can we ruin them but first, we've got a Special Report on an ant colony that was almost destroyed by an errant basketball. Luckily, they've bounced back. For more, we turn to our correspondent out in the field.
MOLLY BLOOM: So anyway, here's the studio. You're going to sit right here.
JAMES ADAMS: This is so exciting. The Brains On studio.
MOLLY BLOOM: I'll sit here and--
SANDEN TOTTEN: Excuse me.
MOLLY BLOOM: I was wondering when you would notice me Oh, hey, Ant. It's been a while, how is your show going?
SANDEN TOTTEN: It was going great until you walked right into the middle of our taping.
MOLLY BLOOM: Your taping? We're supposed to be taping now.
MARK SANCHEZ: Oh, hey, Molly, I was trying to find you. You're taping is at 3 PM central time but the ants, they have this studio booked at 3 PM Eastern time, so.
MOLLY BLOOM: Oh, OK. Why is the ant news network using our studio anyway? I thought they had their own.
MARK SANCHEZ: I don't know, there was a situation with a basketball or something. Doesn't really matter. We had the free studio time available and ants pay in sugar and I love sugar. You want some?
JAMES ADAMS: Are you eating handfuls of raw sugar?
MARK SANCHEZ: Yeah, I figure you did straight, cut out the middleman.
MOLLY BLOOM: About the studio, what do we do? Our co-host James is here now. I don't really want to make him wait.
MARK SANCHEZ: I don't know, what if we combine tapings, isn't the episode today all about ants and spiders anyway?
SANDEN TOTTEN: You're doing an episode on ants and you didn't call us.
MOLLY BLOOM: Sanden, we were trying to avoid what happened last time when the ants took over the studio. It took weeks to get them all out of there. Oh, and, of course, we tried to reach you but your voicemail was full. Yeah, that's it. Your voicemail, full voice mailbox.
SANDEN TOTTEN: Wow, that works out great. So glad we're here. Let's do this.
MOLLY BLOOM: OK.
JAMES ADAMS: It's going to be great.
[MUSIC PLAYING]
MOLLY BLOOM: You're listening to Brains On from American Public Media. I'm Molly Bloom,
SANDEN TOTTEN: And I'm an ant from the Ant News Network.
MOLLY BLOOM: Right, and my co-host today is 9-year-old James Adams from Flower Mound, Texas. Welcome, James.
JAMES ADAMS: Hello, Molly.
MOLLY BLOOM: James, what is your favorite thing about ants?
JAMES ADAMS: The fact that they can carry, like, 10 to 15 times their body weight.
SANDEN TOTTEN: Yes, we are super cool.
MOLLY BLOOM: Today, we're thinking about wall walking and it's all inspired by this question.
SUBJECT 1: My name is Alex from SeaTac, Washington. My question is, how do you creatures like ants and spiders walk on walls?
MOLLY BLOOM: It's a great question.
SANDEN TOTTEN: Yes, a really good question. Not sure why you'd want to know about spiders though. Those weirdos have too many legs. Eight, that's excessive. Six is all you need.
JAMES ADAMS: So Ant, how do you walk on walls?
SANDEN TOTTEN: When it comes to most ants, there's not just one thing that helps us get vertical take it from ANN honorary correspondent Jordan Greer. He's a PhD student at the University of Chicago who studies ants.
JORDAN GREER: The major one that helps them walk on vertical surfaces or upside down is actually something that's like a suction cup that is at the very tips of their toes. This little suction cup produces this liquid what helps them bind to the actual ground that they're walking on, and they seem to really only use it when they're walking on walls or they're walking completely upside down.
SANDEN TOTTEN: Those suction cups are sticky pads that release a tiny little bit of liquid to help me stay put, kind of like if you were to put water on a piece of plastic wrap. You can slap it on the wall and it will stick to. When I'm just walking on the floor, I rarely use those sticky pads. Mostly, it's just my feet, all six of them.
JORDAN GREER: When it comes to walking up a wall, they only use the pads on their front feet while they actually use hairs on their back feet to help give them that push forward.
SANDEN TOTTEN: Oh, good point, Jordan, sticky pads aren't the only thing that let us ants walk on walls. Foot hair is important too. You know that special hair you have that helps climb stuff,
MOLLY BLOOM: We don't have that.
SANDEN TOTTEN: Yeesh, no wonder you're so helpless. Well, OK, if you think about an ant leg in terms of a human arm, this hair would be right about where your wrist is. When we climb up walls, we use the sticky pads on our front feet to pull and the hairs on our back legs to push. And this, when we go down a wall, the opposite is true. Our back feet use sticky pads and our front legs use the hairs to keep us from falling.
JAMES ADAMS: Whoa, that's amazing.
SANDEN TOTTEN: I know. We are pretty great, right? But wait, I almost forgot our third climbing mechanism, claws. These come in handy when a surface isn't totally smooth. A little help here, Jordan.
JORDAN GREER: For sure. So basically, if it has some kind of a texture turn, it's not a fully smooth surface, it's actually a combination of all three of those different pieces of biology that work together to give them the best ability to walk up that vertical space. So it's going to be a combination of using those suction pads, using the claws, and using those hairs on their back feet, depending on the situation, to help give them that lift.
JAMES ADAMS: So there's really nothing that ants can't climb up?
SANDEN TOTTEN: Well, I mean, Yeah, pretty much. Ants climbing walls and climbing into your heart's James, do not move. Do you see that cone shaped hole of sand behind you?
JAMES ADAMS: You mean this one?
SANDEN TOTTEN: No, don't touch it that looks like the trap of an ant lion.
JAMES ADAMS: Ant lion? 8
SANDEN TOTTEN: Ant lions are no laughing matter to ants.
MOLLY BLOOM: What is an ant lion?
SANDEN TOTTEN: It's an insect when it's grown, it sort of looks like a dragonfly but when it's larva, it looks like a tiny evil beetle of death. These larvae live in pits just like that one. OK, keep it together, ant, keep it together. Jordan, can you talk a little bit about ant lions. I'm just going to take a few careful steps back nice and easy, one leg at a time. You can do this.
JORDAN GREER: So one of the major predators of ants is something called an ant lion and they mostly feed on ants, and they have these pits that are made out of really fine sand and they have evolved a way to basically break down the way the ants can walk. So because they have these tiny pads that lock onto the soil, if a pad locks on to a very fine grain of sand and it gets dislodged, the whole ant will tumble down this sand cone and into the mouths of these ant lions.
SANDEN TOTTEN: OK, I think I'm done here. For Ant News Network, I'm Ant.
JAMES ADAMS: I'm pretty sure this isn't an ant lion. It looks more like a dust bunny.
SANDEN TOTTEN: I'm not taking any chances.
MOLLY BLOOM: OK, Ant, take care of yourself. I understand if you want to take off.
SANDEN TOTTEN: Well, I'm not leaving. I'm just going to go crawl up this wall a little, plus, we already prepaid for the studio with a palette of sugar cubes.
MOLLY BLOOM: OK, well, James, I have something that I need your help with. It's time for the mystery sound.
[MUSIC PLAYING]
Are you ready?
JAMES ADAMS: Yes. I am.
MOLLY BLOOM: All right, here it is.
[CLATTERING]
[TWANGING]
[THUMPING AND TWANGING]
[CLATTERING]
MOLLY BLOOM: James, what do you think that sound was?
JAMES ADAMS: It kind of sounds like a marble run but then the like musical instruments sound like a string plucked thing was throwing me off.
MOLLY BLOOM: Yeah, so like there was that like rattling sound at the beginning but then there was that plucky sound. It's a very strange combination of sounds. Any other thoughts of what it might be?
JAMES ADAMS: No.
MOLLY BLOOM: All right, well, we will hear it again a little later in the show.
[MUSIC PLAYING]
Ant holes are pretty cool but so are wormholes. You know, the idea of a portal in space that takes you from one place to another.
JAMES ADAMS: No one knows if these exist but some scientists think they're possible.
MOLLY BLOOM: We're doing an episode on these cosmic shortcuts and we want to know, what do you think it's like inside one? James, what do you think?
JAMES ADAMS: I think it's like you would see stars flying past you and maybe like a different galaxy.
MOLLY BLOOM: I love it. Well, send us your thoughts on traveling through a wormhole. You can record yourself describing the sights or sounds and send it to us at brainson.org/contact.
JAMES ADAMS: You can also send your mystery sounds or questions.
MOLLY BLOOM: That's how we got this fascinating question.
SUBJECT 2: Hi, Brains On, my name's Amelia and I'm from Wales. Why do bananas make other fruit ripen faster? Thank you.
JAMES ADAMS: The answer is waiting for you at the end of the episode,
MOLLY BLOOM: Along with the latest group of honor roll inductees.
JAMES ADAMS: So stick around. This is Brains On. I'm James.
MOLLY BLOOM: I'm Molly.
SANDEN TOTTEN: And I'm an ant.
MOLLY BLOOM: And you're still here, great. OK, James, we're going to go back to that mystery sound again. We're going to hear one more time. OK, James, what new thoughts do you have after hearing it again?
JAMES ADAMS: I don't know, maybe some things like practicing an instrument in the background. It's hard.
MOLLY BLOOM: This is a really, really hard mystery zone and that is a very good guess. You ready for the answer?
JAMES ADAMS: Yep.
MOLLY BLOOM: All right, here with the answer is Elliot Hawkes. He makes high tech devices that copy ideas from nature, in this case, a type of lizard called a gecko.
ELLIOT HAWKES: So the recording is the sound of me taking a gecko-inspired glove and placing it on a wall, partly lifting myself off the ground and then removing the glove from the wall.
MOLLY BLOOM: So that is that clacking sound you heard tiles falling off the wall as he takes the glove off, and that Plank noise is the sound of the glove tightening. Gecko's feet have these tiny sticky hairs that hold them up when they climb on things. And since geckos are really good at climbing, Elliot wanted to take this idea and make it work for humans. So he made these gripper gloves and they're sticky enough that Elliot has actually used them to climb up glass walls like spider-man. But the gloves aren't sticky like glue sticky.
ELLIOT HAWKES: They don't stick with glue, or wet stuff, or suction or any of that. It's similar material to what might be on like a silicone cooking spatula or it's not that different from the rubber on the bottom of your shoe actually.
SANDEN TOTTEN: I love it when I come across cooking spatulas, especially when there's batter involved. But I have heard terrible things about the bottoms of shoes
MOLLY BLOOM: Right. Anyway, the sticky parts of Elliot's gripper gloves are covered with teeny tiny micro hairs, similar to the hairs geckos have on their feet. And the hairs are really, really small. They're even skinnier than human hairs but there are lots and lots and lots of them on the gloves. And when those hairs touch the surface of a wall, all the little particles of the hairs, the hair molecules, stick to all the little particles of the wall, the wall molecules. Elliot says the hair molecules stick to the wall molecules because of something called van der Waals forces.
ELLIOT HAWKES: Van der Waals forces are attractions between any two molecules. If you bring them close enough, there's actually a little bit of a pull between the two molecules. Now, normally, you can't feel this attraction but the hairs are very close to the surface and therefore, they can feel this van der Waals attraction.
MOLLY BLOOM: Because the hairs are really, really small and because there's so many of them, the Van der Waals forces all add up to be sticky enough to hold up an adult-sized person. The gripper gloves also have some springs to balance all those forces and that's the buoyancy noise in the sound. James, would you like to wear those gripper gloves to climb a building like spider-man?
JAMES ADAMS: Yes. I can climb up until somewhere and play video games from far away and then just do it.
MOLLY BLOOM: So everyone would leave you alone?
JAMES ADAMS: Yeah. Brains brains brains
MOLLY BLOOM: What now? Come in.
MARK SANCHEZ: So sorry to interrupt. There's a spider here
SPIDER: Indeed, eight legs, no antennae, 100% arachnid. I'm a spider and I'm here.
MARK SANCHEZ: He demanded to come into the studio and I'm like a little afraid so Yes, I was like, right away, dude, you can come into the studio just don't touch me. Don't touch, don't touch.
MOLLY BLOOM: How can I help you?
SPIDER: My name's Spiderman, Stan Spiderman, and it's a pleasure to meet you, Molly, James, and
SANDEN TOTTEN: Stanley.
JAMES ADAMS: Did you say your name is Spider-Man?
JORDAN GREER: Spiderman. I get that a lot. No, I'm no superhero saving the world and whatnot, who could be bothered. I am part of a charity though. You know Charlotte's Web? We teach illiterate pigs to read and whatnot.
MOLLY BLOOM: So why are you here, Mr. Spiderman?
SPIDER: Right. My friend Sal-- they're also a spider over there-- well, Sal told me that you were doing an episode about walking on walls and you hadn't talked to any spiders yet.
MOLLY BLOOM: Wait, how did Sal know?
SPIDER: Oh, they're up on the wall right over there in the corner. You see?
MOLLY BLOOM: Oh, Yeah,
JAMES ADAMS: Hi, Sal.
SAL: Hey.
SPIDER: Thanks for the tip, Sal. You see, I'm a reporter for The Daily Web and I thought I could help make sure spiders get their fair shake in this scenario.
MOLLY BLOOM: Why not? I've already lost control of this episode again. Why does this always happen when ants are involved?
SPIDER: Are we ready in the studio? I just need to do a few vocal warm ups. Spider babies, spider babies, spider babies. Homespun webs make good beds, homespun webs make good beds. All arachnids are attractive, all arachnids are attractive. I think I'm ready. OK, roll tape I'm Stan Spider Men and this is the Daily Web.
MOLLY BLOOM: It's still Brains On.
JAMES ADAMS: I love the Daily Web.
SPIDER: When you think of a spider, you might think of our geometrically intricate webs, or maybe you think of our eight legs, or, of course, our appreciation for 1920s Spanish revival architecture.
MOLLY BLOOM: No.
SPIDER: But who out there knows how awesome our feet can be?
JAMES ADAMS: Not me.
SPIDER: Well, they are, and one of the people who does know this fact is Linda Rayor. She knows a lot about spiders because she's an entomologist at Cornell University, and to know us is to love us.
LINDA RAYOR: Spiders are totally cool.
SPIDER: Right back at you, Linda. Cool indeed, especially our feet. Most of us spiders have pads on our feet covered in tiny hairs, and these hairs you see split into even tinier hairs and it's these hairs that help us walk on walls.
LINDA RAYOR: So for example, I think most people know adorable jumping spiders, but some of these jumping spiders may only have 40 of these hairs but the hairs are divided so many times that they've got 660 points per hair. And with all these subdivided hairs, it gives an awful lot of surface area to walk on walls. The other thing that I should mention is that these subdivided hairs, at the end of them, they've got kind of a spatula shape. So each of these little points of the hairs is as broad as possible to make the strongest contact.
SPIDER: And remember those van der Waals forces you heard about earlier, well, geckos aren't the only ones to use them. That's right. All that surface area on the hairs creates more opportunities for that kind of attraction to happen between molecules.
LINDA RAYOR: The force of all these hairs touching the wall is 160 times stronger than the force of gravity. That's awesome.
SPIDER: Yes, Linda, it is awesome, factual and awesome.
LINDA RAYOR: There's big tarantulas. They're able to walk up sheets of glass and hang upside down from the ceiling and they're doing it like they're walking on the ground. It's amazing. They don't just have hairs that are on the tips of their feet, but they have hairs that go up the first two joints of their legs. So they may have a million points of contact on a wall and they don't hesitate, they can run anywhere.
SPIDER: Now, I'm sure by now you're thinking, spiders, could they be more amazing? Well, the answer is yes. Yes, we can. Remember those geckos you heard about earlier? Tell them, Linda.
LINDA RAYOR: I once had a specialist who studied geckos come into my lab and he said, nothing can run on polished aluminum. Nothing can move on it, even my geckos just fall off, and I said, no, no, no, my Huntsman spiders can walk on this, no problem. And I put a Huntsman spider at the bottom of a cone of this aluminum and the spider just went and ran up it and I was able to grab it as it came up to the top. Just no issues at all. They're not worrying about gravity
SPIDER: Conquerors of aluminum, scalars of walls, patrons of the opera. Spiders are awesome. For The Daily Web, I'm Stan Spider.
MOLLY BLOOM: Wow, thanks, Stan, very impressive. James, what was the most surprising thing you learned from Stan and Linda?
JAMES ADAMS: Probably that the force is like 160 times more strong than gravity.
MOLLY BLOOM: Yeah, it's very impressive. So I guess that's why spiders can go so many amazing places.
SANDEN TOTTEN: The most surprising thing to me was that spiders don't even have a queen and there's no way they could run a massive colony.
SPIDER: No, ants are just jealous because we have more legs and more eyes.
SANDEN TOTTEN: Oh, eight eyes, big deal. Our eyes are compound eyes which are super cool, plus, we have three other simple eyes that can detect light.
MOLLY BLOOM: OK, OK, let's not fight about facts. If we're going to do this, let's do it right.
SPIDER: What's that, Molly?
MOLLY BLOOM: James, we're going to play a game. It's called identi-fact. I'm going to tell you a cool fact and you're going to identify it as a spider fact or an ant fact.
SANDEN TOTTEN: Are there any cool facts about spiders?
SPIDER: LOL, ant, LOL.
MOLLY BLOOM: You ready, James? Should we do it?
JAMES ADAMS: Yes.
MOLLY BLOOM: All right, listener pals, you can play along too, get a pencil and paper to keep your score. OK, here we go. One species of this animal can jump by using its powerful jaws to launch into the air, spider fact or ant fact?
JAMES ADAMS: Spider fact
MOLLY BLOOM: Oh, it's actually an ant fact. The trap giant ant can fling itself into the air to avoid predators but in general, very few species of ants can jump. A group of them is called a clutter or a cluster, spider fact or ant fact?
JAMES ADAMS: That is spider fact.
MOLLY BLOOM: Correct, correct, a group of ants is a colony. Some species can fly using a technique called ballooning, spider fact or ant fact?
JAMES ADAMS: I think is a spider fact. I mean, ant fact.
MOLLY BLOOM: Oh are you sure? Maybe you should go with your gut.
JAMES ADAMS: A spider fact.
MOLLY BLOOM: Yes, exactly. Certain spiders can release a thin thread of silk into the air and that will catch wind currents and even electric currents to carry the critter to new places. Nicknamed Dracula, this species has the fastest jaws known to science, spider fact or ant fact?
JAMES ADAMS: I think it's an ant fact.
MOLLY BLOOM: Correct, the so-called Dracula ant can snap its jaw at over 200 miles per hour, making it the fastest animal appendage we know of so far. Some versions of this creature can actually shoot little hairs at attackers, sort of, like a porcupine.
JAMES ADAMS: That is a spider fact.
MOLLY BLOOM: You are correct. Tarantulas can launch hairs from their abdomen to thwart predators, wear eye protection when handling these arachnids. This creature is believed to have perhaps the most painful stings in the animal Kingdom, spider fact or ant fact?
JAMES ADAMS: Is ant fact.
MOLLY BLOOM: You are correct. The South American bullet ant is said to be one of the worst stings imaginable, so don't step on these creatures. And that is it. Nice job, James. You did so well in this round identi-fact.
SPIDER: Now wait a minute, a jaw that snaps over 200 miles per hour. You ants are pretty fierce.
SANDEN TOTTEN: You spiders aren't so bad yourselves. Ballooning that sounds so fun. I would love to see how you do it.
SPIDER: Well, I actually can't do that myself but Sal can. Sal, want to show an ant here how you balloon.
INTERVIEWER 4: Yeah, sure.
SPIDER: It's going to work best if we're outside, shall we?
MOLLY BLOOM: Oh, great. Yes, you should go outside. I can call the elevator for you
SPIDER: Molly, please, an elevator.
SANDEN TOTTEN: Silly human. We can just walk out the window and down the side of Brains On headquarters.
SPIDER: Oh, goodness.
JAMES ADAMS: Ants and spiders have some built in tools that help them walk on walls.
MOLLY BLOOM: Ants use pads that stick, claws that grab, and hairs that help push to walk up vertical surfaces.
JAMES ADAMS: Most spiders have lots of tiny hairs on their feet that help them create lots of temporary bonds with the surface they're rocking on.
MOLLY BLOOM: These are called van der Waals forces and even though these bonds are teeny tiny, a bunch of them together, it can be seriously sticky.
JAMES ADAMS: That's it for this episode of Brains On. Brains on is produced by Mark Sanchez, Sanden Totten, and Molly Bloom.
MOLLY BLOOM: Monica Wilhelm is our very mellow fellow. We had production help this week from Doug Ryan and Emily Bright and engineering help from Eric Bright, Erik Stromstad, Veronica Rodriguez, and Bert Odom Reid. Many Thanks to Tracy Mumford, Christopher Clemente and Paul Tosto.
JAMES ADAMS: We're a nonprofit Public Radio show and your support keeps us going.
MOLLY BLOOM: Find out how you can support the show by visiting brainson.org/donate and see the cool thank you gifts we have to offer.
JAMES ADAMS: Before we go, it's time for our moment of--
[CHORUS OF "UM"]
CHILD: Why do bananas make other fruit ripen faster? Thank you.
SARA FARHAT JARRAR: Hi, my name is Sara Farhat Jarrar and I'm a nutritionist. So bananas make other fruits ripe and faster because bananas produce a gas called ethylene, and other fruits do this as well but bananas are pretty famous for this gas. And what ethylene does is it stimulates the ripening processes inside the fruit itself but also when it's close to other fruits.
The ethylene gas allows for the natural aging processes within the fruits to occur. So it's considered like a plant hormone. First of all chlorophyll, which is the green pigment and unripe and fruit, starts changing into other compounds, either red, orange, and yellow, and thus we see the color change as fruit ripen. And what also happens is starch, which is a complex carbohydrate, it starts getting broken down into the simple sugars and that's why fruit becomes sweeter as it ripens.
And also acids that are present in unripe fruits are changing as well into non-acidic sweet compounds and that's why the pungency or sourness of unripe fruit changes as it ripens. And that's all due to the presence of ethylene. So bananas have it, apples have it, pears, melon, kiwi, mango. So a lot of the fruit have it and they produce it even more as they ripen as well, especially like if fruit are put in a closed bag or compartment with ripening fruit, that speeds up the ripening process because the ethylene becomes concentrated in a small area.
MOLLY BLOOM: Here's a list that's always fresh. It's the latest group of listeners to be added to the Brains' honor roll. These are the kids that send in questions, mystery sounds, and drawings to help fuel the show.
[LISTING HONOR ROLL]
JAMES ADAMS: Thanks for listening.
NARRATOR 2: Brains On is supported in part by a grant from the National Science Foundation.
SANDEN TOTTEN: I'm Ant and you're listening to the Ant News Network coming up picnics where are they and how can we ruin them but first, we've got a Special Report on an ant colony that was almost destroyed by an errant basketball. Luckily, they've bounced back. For more, we turn to our correspondent out in the field.
MOLLY BLOOM: So anyway, here's the studio. You're going to sit right here.
JAMES ADAMS: This is so exciting. The Brains On studio.
MOLLY BLOOM: I'll sit here and--
SANDEN TOTTEN: Excuse me.
MOLLY BLOOM: I was wondering when you would notice me Oh, hey, Ant. It's been a while, how is your show going?
SANDEN TOTTEN: It was going great until you walked right into the middle of our taping.
MOLLY BLOOM: Your taping? We're supposed to be taping now.
MARK SANCHEZ: Oh, hey, Molly, I was trying to find you. You're taping is at 3 PM central time but the ants, they have this studio booked at 3 PM Eastern time, so.
MOLLY BLOOM: Oh, OK. Why is the ant news network using our studio anyway? I thought they had their own.
MARK SANCHEZ: I don't know, there was a situation with a basketball or something. Doesn't really matter. We had the free studio time available and ants pay in sugar and I love sugar. You want some?
JAMES ADAMS: Are you eating handfuls of raw sugar?
MARK SANCHEZ: Yeah, I figure you did straight, cut out the middleman.
MOLLY BLOOM: About the studio, what do we do? Our co-host James is here now. I don't really want to make him wait.
MARK SANCHEZ: I don't know, what if we combine tapings, isn't the episode today all about ants and spiders anyway?
SANDEN TOTTEN: You're doing an episode on ants and you didn't call us.
MOLLY BLOOM: Sanden, we were trying to avoid what happened last time when the ants took over the studio. It took weeks to get them all out of there. Oh, and, of course, we tried to reach you but your voicemail was full. Yeah, that's it. Your voicemail, full voice mailbox.
SANDEN TOTTEN: Wow, that works out great. So glad we're here. Let's do this.
MOLLY BLOOM: OK.
JAMES ADAMS: It's going to be great.
[MUSIC PLAYING]
MOLLY BLOOM: You're listening to Brains On from American Public Media. I'm Molly Bloom,
SANDEN TOTTEN: And I'm an ant from the Ant News Network.
MOLLY BLOOM: Right, and my co-host today is 9-year-old James Adams from Flower Mound, Texas. Welcome, James.
JAMES ADAMS: Hello, Molly.
MOLLY BLOOM: James, what is your favorite thing about ants?
JAMES ADAMS: The fact that they can carry, like, 10 to 15 times their body weight.
SANDEN TOTTEN: Yes, we are super cool.
MOLLY BLOOM: Today, we're thinking about wall walking and it's all inspired by this question.
SUBJECT 1: My name is Alex from SeaTac, Washington. My question is, how do you creatures like ants and spiders walk on walls?
MOLLY BLOOM: It's a great question.
SANDEN TOTTEN: Yes, a really good question. Not sure why you'd want to know about spiders though. Those weirdos have too many legs. Eight, that's excessive. Six is all you need.
JAMES ADAMS: So Ant, how do you walk on walls?
SANDEN TOTTEN: When it comes to most ants, there's not just one thing that helps us get vertical take it from ANN honorary correspondent Jordan Greer. He's a PhD student at the University of Chicago who studies ants.
JORDAN GREER: The major one that helps them walk on vertical surfaces or upside down is actually something that's like a suction cup that is at the very tips of their toes. This little suction cup produces this liquid what helps them bind to the actual ground that they're walking on, and they seem to really only use it when they're walking on walls or they're walking completely upside down.
SANDEN TOTTEN: Those suction cups are sticky pads that release a tiny little bit of liquid to help me stay put, kind of like if you were to put water on a piece of plastic wrap. You can slap it on the wall and it will stick to. When I'm just walking on the floor, I rarely use those sticky pads. Mostly, it's just my feet, all six of them.
JORDAN GREER: When it comes to walking up a wall, they only use the pads on their front feet while they actually use hairs on their back feet to help give them that push forward.
SANDEN TOTTEN: Oh, good point, Jordan, sticky pads aren't the only thing that let us ants walk on walls. Foot hair is important too. You know that special hair you have that helps climb stuff,
MOLLY BLOOM: We don't have that.
SANDEN TOTTEN: Yeesh, no wonder you're so helpless. Well, OK, if you think about an ant leg in terms of a human arm, this hair would be right about where your wrist is. When we climb up walls, we use the sticky pads on our front feet to pull and the hairs on our back legs to push. And this, when we go down a wall, the opposite is true. Our back feet use sticky pads and our front legs use the hairs to keep us from falling.
JAMES ADAMS: Whoa, that's amazing.
SANDEN TOTTEN: I know. We are pretty great, right? But wait, I almost forgot our third climbing mechanism, claws. These come in handy when a surface isn't totally smooth. A little help here, Jordan.
JORDAN GREER: For sure. So basically, if it has some kind of a texture turn, it's not a fully smooth surface, it's actually a combination of all three of those different pieces of biology that work together to give them the best ability to walk up that vertical space. So it's going to be a combination of using those suction pads, using the claws, and using those hairs on their back feet, depending on the situation, to help give them that lift.
JAMES ADAMS: So there's really nothing that ants can't climb up?
SANDEN TOTTEN: Well, I mean, Yeah, pretty much. Ants climbing walls and climbing into your heart's James, do not move. Do you see that cone shaped hole of sand behind you?
JAMES ADAMS: You mean this one?
SANDEN TOTTEN: No, don't touch it that looks like the trap of an ant lion.
JAMES ADAMS: Ant lion? 8
SANDEN TOTTEN: Ant lions are no laughing matter to ants.
MOLLY BLOOM: What is an ant lion?
SANDEN TOTTEN: It's an insect when it's grown, it sort of looks like a dragonfly but when it's larva, it looks like a tiny evil beetle of death. These larvae live in pits just like that one. OK, keep it together, ant, keep it together. Jordan, can you talk a little bit about ant lions. I'm just going to take a few careful steps back nice and easy, one leg at a time. You can do this.
JORDAN GREER: So one of the major predators of ants is something called an ant lion and they mostly feed on ants, and they have these pits that are made out of really fine sand and they have evolved a way to basically break down the way the ants can walk. So because they have these tiny pads that lock onto the soil, if a pad locks on to a very fine grain of sand and it gets dislodged, the whole ant will tumble down this sand cone and into the mouths of these ant lions.
SANDEN TOTTEN: OK, I think I'm done here. For Ant News Network, I'm Ant.
JAMES ADAMS: I'm pretty sure this isn't an ant lion. It looks more like a dust bunny.
SANDEN TOTTEN: I'm not taking any chances.
MOLLY BLOOM: OK, Ant, take care of yourself. I understand if you want to take off.
SANDEN TOTTEN: Well, I'm not leaving. I'm just going to go crawl up this wall a little, plus, we already prepaid for the studio with a palette of sugar cubes.
MOLLY BLOOM: OK, well, James, I have something that I need your help with. It's time for the mystery sound.
[MUSIC PLAYING]
Are you ready?
JAMES ADAMS: Yes. I am.
MOLLY BLOOM: All right, here it is.
[CLATTERING]
[TWANGING]
[THUMPING AND TWANGING]
[CLATTERING]
MOLLY BLOOM: James, what do you think that sound was?
JAMES ADAMS: It kind of sounds like a marble run but then the like musical instruments sound like a string plucked thing was throwing me off.
MOLLY BLOOM: Yeah, so like there was that like rattling sound at the beginning but then there was that plucky sound. It's a very strange combination of sounds. Any other thoughts of what it might be?
JAMES ADAMS: No.
MOLLY BLOOM: All right, well, we will hear it again a little later in the show.
[MUSIC PLAYING]
Ant holes are pretty cool but so are wormholes. You know, the idea of a portal in space that takes you from one place to another.
JAMES ADAMS: No one knows if these exist but some scientists think they're possible.
MOLLY BLOOM: We're doing an episode on these cosmic shortcuts and we want to know, what do you think it's like inside one? James, what do you think?
JAMES ADAMS: I think it's like you would see stars flying past you and maybe like a different galaxy.
MOLLY BLOOM: I love it. Well, send us your thoughts on traveling through a wormhole. You can record yourself describing the sights or sounds and send it to us at brainson.org/contact.
JAMES ADAMS: You can also send your mystery sounds or questions.
MOLLY BLOOM: That's how we got this fascinating question.
SUBJECT 2: Hi, Brains On, my name's Amelia and I'm from Wales. Why do bananas make other fruit ripen faster? Thank you.
JAMES ADAMS: The answer is waiting for you at the end of the episode,
MOLLY BLOOM: Along with the latest group of honor roll inductees.
JAMES ADAMS: So stick around. This is Brains On. I'm James.
MOLLY BLOOM: I'm Molly.
SANDEN TOTTEN: And I'm an ant.
MOLLY BLOOM: And you're still here, great. OK, James, we're going to go back to that mystery sound again. We're going to hear one more time. OK, James, what new thoughts do you have after hearing it again?
JAMES ADAMS: I don't know, maybe some things like practicing an instrument in the background. It's hard.
MOLLY BLOOM: This is a really, really hard mystery zone and that is a very good guess. You ready for the answer?
JAMES ADAMS: Yep.
MOLLY BLOOM: All right, here with the answer is Elliot Hawkes. He makes high tech devices that copy ideas from nature, in this case, a type of lizard called a gecko.
ELLIOT HAWKES: So the recording is the sound of me taking a gecko-inspired glove and placing it on a wall, partly lifting myself off the ground and then removing the glove from the wall.
MOLLY BLOOM: So that is that clacking sound you heard tiles falling off the wall as he takes the glove off, and that Plank noise is the sound of the glove tightening. Gecko's feet have these tiny sticky hairs that hold them up when they climb on things. And since geckos are really good at climbing, Elliot wanted to take this idea and make it work for humans. So he made these gripper gloves and they're sticky enough that Elliot has actually used them to climb up glass walls like spider-man. But the gloves aren't sticky like glue sticky.
ELLIOT HAWKES: They don't stick with glue, or wet stuff, or suction or any of that. It's similar material to what might be on like a silicone cooking spatula or it's not that different from the rubber on the bottom of your shoe actually.
SANDEN TOTTEN: I love it when I come across cooking spatulas, especially when there's batter involved. But I have heard terrible things about the bottoms of shoes
MOLLY BLOOM: Right. Anyway, the sticky parts of Elliot's gripper gloves are covered with teeny tiny micro hairs, similar to the hairs geckos have on their feet. And the hairs are really, really small. They're even skinnier than human hairs but there are lots and lots and lots of them on the gloves. And when those hairs touch the surface of a wall, all the little particles of the hairs, the hair molecules, stick to all the little particles of the wall, the wall molecules. Elliot says the hair molecules stick to the wall molecules because of something called van der Waals forces.
ELLIOT HAWKES: Van der Waals forces are attractions between any two molecules. If you bring them close enough, there's actually a little bit of a pull between the two molecules. Now, normally, you can't feel this attraction but the hairs are very close to the surface and therefore, they can feel this van der Waals attraction.
MOLLY BLOOM: Because the hairs are really, really small and because there's so many of them, the Van der Waals forces all add up to be sticky enough to hold up an adult-sized person. The gripper gloves also have some springs to balance all those forces and that's the buoyancy noise in the sound. James, would you like to wear those gripper gloves to climb a building like spider-man?
JAMES ADAMS: Yes. I can climb up until somewhere and play video games from far away and then just do it.
MOLLY BLOOM: So everyone would leave you alone?
JAMES ADAMS: Yeah. Brains brains brains
MOLLY BLOOM: What now? Come in.
MARK SANCHEZ: So sorry to interrupt. There's a spider here
SPIDER: Indeed, eight legs, no antennae, 100% arachnid. I'm a spider and I'm here.
MARK SANCHEZ: He demanded to come into the studio and I'm like a little afraid so Yes, I was like, right away, dude, you can come into the studio just don't touch me. Don't touch, don't touch.
MOLLY BLOOM: How can I help you?
SPIDER: My name's Spiderman, Stan Spiderman, and it's a pleasure to meet you, Molly, James, and
SANDEN TOTTEN: Stanley.
JAMES ADAMS: Did you say your name is Spider-Man?
JORDAN GREER: Spiderman. I get that a lot. No, I'm no superhero saving the world and whatnot, who could be bothered. I am part of a charity though. You know Charlotte's Web? We teach illiterate pigs to read and whatnot.
MOLLY BLOOM: So why are you here, Mr. Spiderman?
SPIDER: Right. My friend Sal-- they're also a spider over there-- well, Sal told me that you were doing an episode about walking on walls and you hadn't talked to any spiders yet.
MOLLY BLOOM: Wait, how did Sal know?
SPIDER: Oh, they're up on the wall right over there in the corner. You see?
MOLLY BLOOM: Oh, Yeah,
JAMES ADAMS: Hi, Sal.
SAL: Hey.
SPIDER: Thanks for the tip, Sal. You see, I'm a reporter for The Daily Web and I thought I could help make sure spiders get their fair shake in this scenario.
MOLLY BLOOM: Why not? I've already lost control of this episode again. Why does this always happen when ants are involved?
SPIDER: Are we ready in the studio? I just need to do a few vocal warm ups. Spider babies, spider babies, spider babies. Homespun webs make good beds, homespun webs make good beds. All arachnids are attractive, all arachnids are attractive. I think I'm ready. OK, roll tape I'm Stan Spider Men and this is the Daily Web.
MOLLY BLOOM: It's still Brains On.
JAMES ADAMS: I love the Daily Web.
SPIDER: When you think of a spider, you might think of our geometrically intricate webs, or maybe you think of our eight legs, or, of course, our appreciation for 1920s Spanish revival architecture.
MOLLY BLOOM: No.
SPIDER: But who out there knows how awesome our feet can be?
JAMES ADAMS: Not me.
SPIDER: Well, they are, and one of the people who does know this fact is Linda Rayor. She knows a lot about spiders because she's an entomologist at Cornell University, and to know us is to love us.
LINDA RAYOR: Spiders are totally cool.
SPIDER: Right back at you, Linda. Cool indeed, especially our feet. Most of us spiders have pads on our feet covered in tiny hairs, and these hairs you see split into even tinier hairs and it's these hairs that help us walk on walls.
LINDA RAYOR: So for example, I think most people know adorable jumping spiders, but some of these jumping spiders may only have 40 of these hairs but the hairs are divided so many times that they've got 660 points per hair. And with all these subdivided hairs, it gives an awful lot of surface area to walk on walls. The other thing that I should mention is that these subdivided hairs, at the end of them, they've got kind of a spatula shape. So each of these little points of the hairs is as broad as possible to make the strongest contact.
SPIDER: And remember those van der Waals forces you heard about earlier, well, geckos aren't the only ones to use them. That's right. All that surface area on the hairs creates more opportunities for that kind of attraction to happen between molecules.
LINDA RAYOR: The force of all these hairs touching the wall is 160 times stronger than the force of gravity. That's awesome.
SPIDER: Yes, Linda, it is awesome, factual and awesome.
LINDA RAYOR: There's big tarantulas. They're able to walk up sheets of glass and hang upside down from the ceiling and they're doing it like they're walking on the ground. It's amazing. They don't just have hairs that are on the tips of their feet, but they have hairs that go up the first two joints of their legs. So they may have a million points of contact on a wall and they don't hesitate, they can run anywhere.
SPIDER: Now, I'm sure by now you're thinking, spiders, could they be more amazing? Well, the answer is yes. Yes, we can. Remember those geckos you heard about earlier? Tell them, Linda.
LINDA RAYOR: I once had a specialist who studied geckos come into my lab and he said, nothing can run on polished aluminum. Nothing can move on it, even my geckos just fall off, and I said, no, no, no, my Huntsman spiders can walk on this, no problem. And I put a Huntsman spider at the bottom of a cone of this aluminum and the spider just went and ran up it and I was able to grab it as it came up to the top. Just no issues at all. They're not worrying about gravity
SPIDER: Conquerors of aluminum, scalars of walls, patrons of the opera. Spiders are awesome. For The Daily Web, I'm Stan Spider.
MOLLY BLOOM: Wow, thanks, Stan, very impressive. James, what was the most surprising thing you learned from Stan and Linda?
JAMES ADAMS: Probably that the force is like 160 times more strong than gravity.
MOLLY BLOOM: Yeah, it's very impressive. So I guess that's why spiders can go so many amazing places.
SANDEN TOTTEN: The most surprising thing to me was that spiders don't even have a queen and there's no way they could run a massive colony.
SPIDER: No, ants are just jealous because we have more legs and more eyes.
SANDEN TOTTEN: Oh, eight eyes, big deal. Our eyes are compound eyes which are super cool, plus, we have three other simple eyes that can detect light.
MOLLY BLOOM: OK, OK, let's not fight about facts. If we're going to do this, let's do it right.
SPIDER: What's that, Molly?
MOLLY BLOOM: James, we're going to play a game. It's called identi-fact. I'm going to tell you a cool fact and you're going to identify it as a spider fact or an ant fact.
SANDEN TOTTEN: Are there any cool facts about spiders?
SPIDER: LOL, ant, LOL.
MOLLY BLOOM: You ready, James? Should we do it?
JAMES ADAMS: Yes.
MOLLY BLOOM: All right, listener pals, you can play along too, get a pencil and paper to keep your score. OK, here we go. One species of this animal can jump by using its powerful jaws to launch into the air, spider fact or ant fact?
JAMES ADAMS: Spider fact
MOLLY BLOOM: Oh, it's actually an ant fact. The trap giant ant can fling itself into the air to avoid predators but in general, very few species of ants can jump. A group of them is called a clutter or a cluster, spider fact or ant fact?
JAMES ADAMS: That is spider fact.
MOLLY BLOOM: Correct, correct, a group of ants is a colony. Some species can fly using a technique called ballooning, spider fact or ant fact?
JAMES ADAMS: I think is a spider fact. I mean, ant fact.
MOLLY BLOOM: Oh are you sure? Maybe you should go with your gut.
JAMES ADAMS: A spider fact.
MOLLY BLOOM: Yes, exactly. Certain spiders can release a thin thread of silk into the air and that will catch wind currents and even electric currents to carry the critter to new places. Nicknamed Dracula, this species has the fastest jaws known to science, spider fact or ant fact?
JAMES ADAMS: I think it's an ant fact.
MOLLY BLOOM: Correct, the so-called Dracula ant can snap its jaw at over 200 miles per hour, making it the fastest animal appendage we know of so far. Some versions of this creature can actually shoot little hairs at attackers, sort of, like a porcupine.
JAMES ADAMS: That is a spider fact.
MOLLY BLOOM: You are correct. Tarantulas can launch hairs from their abdomen to thwart predators, wear eye protection when handling these arachnids. This creature is believed to have perhaps the most painful stings in the animal Kingdom, spider fact or ant fact?
JAMES ADAMS: Is ant fact.
MOLLY BLOOM: You are correct. The South American bullet ant is said to be one of the worst stings imaginable, so don't step on these creatures. And that is it. Nice job, James. You did so well in this round identi-fact.
SPIDER: Now wait a minute, a jaw that snaps over 200 miles per hour. You ants are pretty fierce.
SANDEN TOTTEN: You spiders aren't so bad yourselves. Ballooning that sounds so fun. I would love to see how you do it.
SPIDER: Well, I actually can't do that myself but Sal can. Sal, want to show an ant here how you balloon.
INTERVIEWER 4: Yeah, sure.
SPIDER: It's going to work best if we're outside, shall we?
MOLLY BLOOM: Oh, great. Yes, you should go outside. I can call the elevator for you
SPIDER: Molly, please, an elevator.
SANDEN TOTTEN: Silly human. We can just walk out the window and down the side of Brains On headquarters.
SPIDER: Oh, goodness.
JAMES ADAMS: Ants and spiders have some built in tools that help them walk on walls.
MOLLY BLOOM: Ants use pads that stick, claws that grab, and hairs that help push to walk up vertical surfaces.
JAMES ADAMS: Most spiders have lots of tiny hairs on their feet that help them create lots of temporary bonds with the surface they're rocking on.
MOLLY BLOOM: These are called van der Waals forces and even though these bonds are teeny tiny, a bunch of them together, it can be seriously sticky.
JAMES ADAMS: That's it for this episode of Brains On. Brains on is produced by Mark Sanchez, Sanden Totten, and Molly Bloom.
MOLLY BLOOM: Monica Wilhelm is our very mellow fellow. We had production help this week from Doug Ryan and Emily Bright and engineering help from Eric Bright, Erik Stromstad, Veronica Rodriguez, and Bert Odom Reid. Many Thanks to Tracy Mumford, Christopher Clemente and Paul Tosto.
JAMES ADAMS: We're a nonprofit Public Radio show and your support keeps us going.
MOLLY BLOOM: Find out how you can support the show by visiting brainson.org/donate and see the cool thank you gifts we have to offer.
JAMES ADAMS: Before we go, it's time for our moment of--
[CHORUS OF "UM"]
CHILD: Why do bananas make other fruit ripen faster? Thank you.
SARA FARHAT JARRAR: Hi, my name is Sara Farhat Jarrar and I'm a nutritionist. So bananas make other fruits ripe and faster because bananas produce a gas called ethylene, and other fruits do this as well but bananas are pretty famous for this gas. And what ethylene does is it stimulates the ripening processes inside the fruit itself but also when it's close to other fruits.
The ethylene gas allows for the natural aging processes within the fruits to occur. So it's considered like a plant hormone. First of all chlorophyll, which is the green pigment and unripe and fruit, starts changing into other compounds, either red, orange, and yellow, and thus we see the color change as fruit ripen. And what also happens is starch, which is a complex carbohydrate, it starts getting broken down into the simple sugars and that's why fruit becomes sweeter as it ripens.
And also acids that are present in unripe fruits are changing as well into non-acidic sweet compounds and that's why the pungency or sourness of unripe fruit changes as it ripens. And that's all due to the presence of ethylene. So bananas have it, apples have it, pears, melon, kiwi, mango. So a lot of the fruit have it and they produce it even more as they ripen as well, especially like if fruit are put in a closed bag or compartment with ripening fruit, that speeds up the ripening process because the ethylene becomes concentrated in a small area.
MOLLY BLOOM: Here's a list that's always fresh. It's the latest group of listeners to be added to the Brains' honor roll. These are the kids that send in questions, mystery sounds, and drawings to help fuel the show.
[LISTING HONOR ROLL]
JAMES ADAMS: Thanks for listening.
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