How Frogs Work | Stuff You Should Know Podcast (Transcript)
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How Frogs Work | Stuff You Should Know Podcast (Transcript)
Length: 54 mins
Welcome to you Stuff You Should Know, from howstuffworks.com.
Josh Clark: Hey, and welcome to the podcast. I‚Äôm Josh Clark and there‚Äôs Charles W. ‚ÄúRivet‚Äù Bryant. There‚Äôs Jerry ‚ÄúBudweiser‚Äù Roland.
Charles W. Chuck Bryant: [Laughs] Oh man, that‚Äôs a‚Ä¶ Old call back. The Budweiser frogs.
JC: Yeah, man. They were no Spuds McKenzie, I‚Äôll tell you that.
CB: I know. Remember when they were on their lily pads going, ‚ÄúWassuuup!
JC: Oh, yeah, I loved that guy, those guys. Man, we‚Äôve seen a lot of ads in our lifetime, haven‚Äôt we?
CB: We‚Äôve recorded a lot of ads in our lifetime.
JC: We have, we‚Äôve really been contributing to the pile. How you feeling?
CB: I‚Äôm feeling great.
JC: You‚Äôre feeling froggy?
JC: I‚Äôm really sorry. I had no idea this was gonna happen.
CB: I am feeling froggy and, right off the bat, we should go ahead and thank Tracy ‚ÄúTV‚Äù Wilson, Tracy V. Wilson. From Stuff You Missed in History Class, because this is one of her great, great animal articles.
JC: Yeah, she‚Äôs written the best.
CB: She really has.
JC: This one doesn‚Äôt contain the words ‚Äúmouth‚Ä¶‚Äù What was it mouth?
JC: Mouthparts, that‚Äôs right.
CB: [Laughs] Yeah, she tried to work it in.
JC: It got edited out, I think.
CB: [Laughs] That‚Äôs right.
JC: So we are, we‚Äôre talking frogs today, Chuck. I can‚Äôt believe we haven‚Äôt talked about them before.
CB: I know. I love frogs.
JC: I love them too and it‚Äôs sad for us then because it turns out that frogs, apparently, are going extinct at an alarming rate; entire species just dropping off the face of the earth. In fact, one species went extinct here in our fair city of Atlanta. Did you know that?
CB: Oh, really?
JC: Yeah, last September 2016, so about a year ago. The very last Rabb‚Äôs fringe-limbed treefrog died at the Atlanta Botanical Garden.
CB: Oh, wow.
JC: His name was Tuffy and, from what I understand, he didn‚Äôt like to be handled. That that was his choice, you know? So he was the last of it. The species was found, I think, in the late 80s or late 90s and we figured out, pretty quickly, that they were endangered, and the last one that was heard in the wild was in, I think, 2005. And so they thought Tuffy was the last one and so a frog species went extinct in Atlanta. And, apparently, that‚Äôs just one domino out of many.
JC: That‚Äôs going on right now. There was a study from 2015 that concluded 3%, which is about 200 species, of frog species have gone extinct since the 1970s, right? Which is like, ‚ÄúWow, that‚Äôs‚Ä¶‚Äù Seems like a lot. Prepare for it to seem like even more. You‚Äôre ready for this?
JC: So amphibians and reptiles have really high extinction rates as it is. They, apparently, have an extinction rate of about 10,000 times other animals.
JC: And frogs‚Äô extinction rate is higher than most other amphibians and reptiles. So the frogs are going fast and the reason why it matters, besides the fact that we love frogs, is that they‚Äôre also known as an indicator species. They‚Äôre particularly fragile, they‚Äôre found all over the world, and they seem to be trying to tell us that the earth is going lopsided as far as the global ecosystem goes.
CB: That‚Äôs sad.
CB: Remember, we talked about those and, I think, it was Charismatic Megafauna?
JC: Yeah, I guess so.
CB: All right. So, we might as well get into this. I almost said jump into this, but now I‚Äôm hyper-aware of bad frog puns.
JC: Yeah, sorry for everything.
CB: So Tracy makes a great point here. Talking about frogs, and if you just said there, what 3% of different species is 200?
CB: So that shows you how many different species there are.
CB: It‚Äôs difficult to kind of talk about frogs in one big sweeping way because they differ so much species to species. They can be, what is it, the Gold Frog is less than a centimeter.
CB: Then you have Goliath Frogs.
JC: Oh, man.
CB: That are over a foot.
CB: Head to tail.
JC: A foot? 32 centimeters?
CB: Yeah, a lot of them like to be out at night, some of them are more active in the morning and the afternoon, sometimes they live for a couple years, sometimes they live, well, not many, many years, but several years.
JC: Yeah. One of the main things that frogs are known for, which is croaking or ribbiting, it would seem like that‚Äôs universal; it‚Äôs not. There‚Äôs plenty of species that don‚Äôt make any noise.
CB: Yeah, you think of green or brown, there are pink frogs.
CB: All kinds of colors, there are blue frogs. The difference between toads and frogs isn‚Äôt‚Ä¶ We might as well just consider them one thing from what I can tell, right?
JC: Yeah, toads, true toads belong to the Bufonidae family.
JC: So toads are frogs. But even within that distinction, there are some things that are like, ‚ÄúNo, that‚Äôs actually a toad.‚Äù Like, toads tend to have eyes that are lower on its head.
JC: And more football-shaped, whereas a frog has eyes higher up on its head and they‚Äôre usually quite round, right? But there are certain toads that have those kind of eyes and there are certain frogs that have toad-like eyes. You can‚Äôt pin frogs down.
CB: Unless you‚Äôre in science class. [Laughs]
JC: Right, even with their tails. That was great, man, by the way.
JC: But even with their tails, right? So their order, like I just said, ‚ÄéAnura, means tailless.
JC: And it separates them from the other amphibians, the fact that frogs don‚Äôt have tails across the board. Actually, no; there‚Äôs two species that have tails.
CB: Yeah, they‚Äôre very vexing. There‚Äôs a coastal tailed frog and the mountain tailed frog, and I looked them up. You know, they‚Äôre little tiny tails and they are the reproductive organs of those species.
JC: It‚Äôs a penis, then. I don‚Äôt understand why they don‚Äôt just call it the penis frog. There actually is a scrotum frog. And get this, there‚Äôs a scrotum frog population at Lake Titicaca.
JC: You can‚Äôt make this up. This is what frogs are here for. It‚Äôs just to say amazing things.
CB: Here‚Äôs one thing I didn‚Äôt know, and we‚Äôre gonna be dropping in frog facts throughout, they molt. I had no idea that frogs can molt. Every two days they can molt.
CB: And they start out by eating their own skin around its mouth. They basically eat the skin around the mouth then pull the rest of their skin over their head like a dirty tee shirt, and then they eat that like a dirty tee shirt.
JC: Right. Imagine that, man. You know when your lip gets chapped and you kind of bite it, like a little piece, and you pull it off and it‚Äôs like‚Ä¶
CB: I‚Äôm doing that right now.
JC: Oh man, it‚Äôs a little raw.
JC: Imagine if that piece was your whole skin.
JC: And then you‚Äôd be a frog.
CB: [Laughs] Or a toad.
JC: Either one.
CB: I think I‚Äôm more down with the toads because frogs are generally the slicker skin.
CB: Toads are the ones that kind of have the bumpy, drier skin and I think they‚Äôre the ones, when you pick them up and look at them, they stare into your soul right back at you trying to talk.
JC: The toads do?
CB: I think so.
CB: Am I getting that confused with frogs?
JC: I don‚Äôt know. Have you ever kissed a frog?
CB: [Laughs] No, but I would.
JC: Under what circumstances?
CB: I don‚Äôt know. A couple of drinks.
JC: [Laughs] A frog or a toad?
JC: Or would you kiss either one?
CB: I would kiss a toad, but then I would be a little, just because I love animals and think they all deserve affection, but I would not‚Ä¶ I would think twice, and we‚Äôre gonna go over this later, but licking a frog for hallucinogenic, good times.
JC: Yeah, you might want to think even more than twice.
CB: Yeah, I would not want to go down that road.
CB: But we‚Äôll get to that. I think you can kiss a frog and not necessarily hallucinate.
JC: You can. You just have to plant it right on its big old mouth.
CB: That‚Äôs exactly where it goes.
JC: And if the frog really likes you, he‚Äôll be like, ‚ÄúHere, take my skin. I was gonna eat it myself, but you can have it.‚Äù
CB: [Laughs] The reason why I made that bad but good science joke about pinning frogs down is they are one of the go-to animals that you will dissect in school. And the reason why they‚Äôre one of the go-to animals, it‚Äôs not just because teachers hate frogs or that teachers love frogs, but it‚Äôs that frogs, they‚Äôre trying to teach kids about internal organs and not that of a frog; they‚Äôre trying to teach them about themselves because it turns out, when you cut open frog, you might remember this, it‚Äôs not a circuit board or a series of balloons or golf balls. When you cut open a frog, there are heart and lungs and a stomach and a pancreas and a gallbladder and intestines and a liver.
JC: Yeah, largely connected in a way that‚Äôs similar to humans.
CB: Yeah, just all packed in that tiny little guy.
JC: Yeah, I mean they‚Äôre all tiny organs.
CB: Very cute too.
JC: Appropriately sized.
JC: They are cute. Remember that smell, though?
CB: Of the formaldehyde?
JC: The formaldehyde stink of death. Man, that was not a good smell.
CB: That was not good.
JC: And so beyond just the internal organs too, Chuck, if you look at a frog‚Äôs skeleton, especially its arms, its extremities, it bears a resemblance to human anatomy as well, right?
CB: For sure.
JC: You‚Äôve got a humorous, a radius, and an ulna, just like with your arm. And then the frog‚Äôs legs and back, they have a femur, a tibia, and a fibula, just like your legs too.
CB: Yeah, the only difference is the radius and ulna are fused and the tibia and fibula are fused.
CB: Whereas they are not in our bodies.
JC: And they have a scapula and clavicles.
JC: Collarbones and shoulder blades too, right? So they‚Äôre just basically little people with big mouths.
CB: Sort of.
JC: Well, there‚Äôs actually some big differences too.
CB: They have fingers and toes.
JC: They do. They have, usually, and again it‚Äôs tough to generalize here, but a lot of frogs have four fingers on their front feet, and five on their back.
CB: Yeah, and these little digits are gonna vary from species to species according to what the frog‚Äôs locomotion needs are.
CB: So if it‚Äôs a tree frog, they‚Äôre gonna be long and flexy so they can grab stuff, if they‚Äôre swimmers, and all frogs and toads, we should point out, need water to live.
JC: Yeah, we really have to get into that part.
CB: Which we will. But they have little webbed feet and toes, of course.
JC: Yeah, it makes it easier for them to swim.
CB: And what about the little burrowers?
JC: Yeah, some of them, I get the impression that they burrow to hibernate or estivate.
JC: Emilio Estivate. [Chuckles]
JC: We‚Äôre feeling silly today, huh?
CB: I was watching Breakfast Club last night for the first time in years.
JC: How was it?
CB: It holds up, and I know that movie by heart, it‚Äôs really remarkable how well I know that movie.
JC: But it does hold up?
CB: I think so.
CB: The only thing that‚Ä¶ T‚Äôs not a very diverse movie like‚Ä¶
CB: You know, it‚Äôs five white kids and a white principal.
JC: Throwing a little bit of casual racism here there.
CB: Yeah, but I mean, you know, John Hughes has been accused of that in recent years.
JC: Oh, really?
CB: Yeah, just sort of‚Ä¶
JC: Oh, Long Duk Dong was his too, huh?
CB: Of course. And the only time there were people of different ethnicities in his movies, they were kind of joked about or aped.
JC: Yeah. I‚Äôm sure‚Ä¶ It‚Äôs funny how history can just turn on you, you know?
JC: He was probably like, ‚ÄúWait, no. Everybody loves me; I‚Äôm John Hughes. What do you mean?‚Äù
JC: ‚ÄúWe all thought this was great, don‚Äôt you remember? I‚Äôm John Hughes, don‚Äôt you know me?‚Äù
CB: [Laughs] Yeah, it‚Äôs very sad.
CB: He was gone too soon. Where were we? Oh, Emilio Estevez.
JC: Oh, yeah. They Emilio Estivate, which is‚Ä¶
JC: Like hibernation in warm temperatures or hot temperatures, when it gets so hot out.
JC: That, for all intents and purposes, you can‚Äôt go hunt. You‚Äôre just like, ‚ÄúIt‚Äôs too hot.‚Äù
JC: ‚ÄúI‚Äôm gonna dig myself a little hole and lay here until it cools off a little bit.‚Äù
CB: Yeah, and the whole point of that was that their feet and hands are shorter and wider like shovels. And like Emilio Estevez, ironically. [Laughs]
JC: Yeah, that guy can dig a hole faster than anyone you‚Äôve ever seen.
CB: What are some of the different things? They don‚Äôt have necks. If you look at a frog, he doesn‚Äôt have a big long neck that turns around and looks at you; they‚Äôre just sort of these little squat heads sitting directly on their bodies.
JC: Yeah, like Fred Flintstone.
JC: And, as a result, they can‚Äôt turn their heads, right?
JC: They can‚Äôt lift them up or down or turn them.
CB: If a frog ever turns his head and looks at you, then that is a evil possessed frog.
JC: [Chuckles] Right. Which, if a frog sitting there staring at you, especially if they‚Äôre suddenly joined by some companions, you should probably run away.
JC: There‚Äôs just something super creepy about them. I can‚Äôt remember the movie, Chuck. What was the horror movie that features lots and lots of frogs?
CB: Oh, I don‚Äôt know.
JC: It‚Äôs like the point of them. I can‚Äôt remember the name of it. It‚Äôs from the 80s, I believe.
CB: I don‚Äôt know.
JC: I will happily respond to anybody who writes in.
CB: Was it The Day the Frogs Took Over?
JC: [Laughs] That‚Äôs right. The Day the Frogs Stood Still.
JC: Frogs! With an exclamation point.
CB: [Laughs] What else? They don‚Äôt have ribs, they have a pelvis that can slide up and down to help them jump.
JC: I thought that was pretty cool.
CB: Which one, the pelvis?
JC: What, it has a hole in it and it slides up and down the spine?
CB: I think so, so it can help it jump.
JC: Yeah, I think that‚Äôs pretty cool.
CB: And what else?
JC: They have‚Ä¶ Well, their eyes, Chuck, the eyes.
CB: Oh, yes.
JC: Like I said, frogs typically have eyes that sit on the top of their head and they can see quite well in a very wide angle. They have a wide wide view.
JC: Vantage point. Could‚Äôve put that better, but that helps compensate for the fact that they can‚Äôt turn their heads, right?
JC: But apparently, as Tracy says, what one eye is getting in information is not really overlapping with the other eye, so they don‚Äôt have binocular vision; they have vision from two different eyes. And it sounds like, ‚ÄúOkay, whatever. Who cares?‚Äù But if you think about the depth perception it would take to pick a fly out of the air with your tongue‚Ä¶
JC: It suddenly becomes quite impressive that they don‚Äôt seem to have binocular vision.
JC: And have did you do any research on their tongue?
JC: So, Chuck, their tongue, right?
JC: They don‚Äôt have a tongue that‚Äôs anchored to the back of their mouth like we do.
JC: It‚Äôs anchored to the front and they can throw it out. And there‚Äôs this one researcher, who I think is working out of Georgia Tech, who filmed leopard frogs. The leopard frog can catch an insect with its tongue in 0.7 seconds.
JC: Which is five times faster than humans blink.
CB: Holy cow.
JC: Right. So researchers wanted to know how are they doing that? If you‚Äôre hitting on a fly with your tongue, you‚Äôre gonna knock it away from you. How do they grab it?
CB: It‚Äôs sticky, right?
JC: They figured that, yes, there was something sticky and they determined that frogs‚Äô saliva is a non-Newtonian fluid, which, remember we covered that.
CB: Oh yeah.
JC: In the ketchup up episode. And just like ketchup, a frog‚Äôs saliva can turn sticky or it can turn less sticky when you apply force to it. So when the tongue, and the saliva on the tongue more importantly, comes in contact forcefully with an insect, it thins out and it covers the insect. But the moment it starts coming back and the force reverses, and I‚Äôm sure I just got that wrong.
JC: I‚Äôm gonna hear about it, about physics from everybody.
JC: But once it stops being thin, it goes back to being viscous and somewhat sticky, and so now the fly or the insect has been covered in the sticky goo and is attached to the tongue and is being brought back into the frog‚Äôs mouth.
JC: All that happens in less than 1/800 of a second.
CB: That‚Äôs crazy.
CB: I‚Äôm sure they have some pretty super cool slow-mo.
JC: Yeah, they do for sure.
CB: Well, but since you mentioned the tongue, though, because it isn‚Äôt anchored in the back of their mouths, they can‚Äôt use the tongue to push food down. So when a frog eats‚Ä¶ They also don‚Äôt have a jaw that they can chew, like you would think and like humans do.
CB: So they just swallow it in a couple of gulps and they actually, since they can‚Äôt use their tongue, they use their eyeballs.
JC: [Laughs] Yeah.
CB: Their eyes sink into the skull to push food down.
JC: So I just have to ask, Chuck. Where do frogs stand in relation to jellyfish and octopi now?
CB: Oh, wow. Not ahead of those too.
JC: Okay, so third, fourth, fifth, seventeenth?
CB: Well, if we‚Äôre talking all animals, I don‚Äôt know where to rank them, but if we‚Äôre talking crazy Stuff You Should Know animals, I would go with number three.
JC: Got you.
CB: For now.
CB: And on those eyes, they have what‚Äôs called a nictitating, is that right? Nictitating membrane. You‚Äôve probably seen when frogs or toads go to dive underwater, they have a film like‚Ä¶ What‚Äôs the other animal that does that? Seems like we talked about that.
JC: We have.
CB: They have a film that covers the eye.
JC: I think alligators, probably?
CB: Oh, that sounds about right.
JC: Yeah. I think that‚Äôs right, yeah. Which would make sense because alligators are reptiles.
JC: And these guys are somewhat related to reptiles.
CB: All right. So that‚Äôs a lot of initial frog stuff, frog body stuff. So let‚Äôs take a break and let‚Äôs talk a little bit more about frog body stuff. [Chuckles]
JC: All right.
JC: All right, dude, so we‚Äôre back. We were about to talk about frogs getting it on.
CB: Well, quickly though, we never mentioned the ears.
JC: Oh, yeah, that‚Äôs a big one.
CB: You probably noticed that frogs don‚Äôt have these big, funny ears that stick off their head.
CB: They do have ears; they‚Äôre just not external.
JC: That‚Äôd be hilarious.
CB: They just have the little‚Ä¶ [Laughs] That would be funny. They just have the little tympanum, the little eardrum behind each eye.
JC: Yeah, and you can, apparently, if you know what you‚Äôre doing, in most frog species, tell whether a frog is a male or female based on the size of their tympanum to their eyeball. In a male, I think the tympanum is bigger than the eye and, in a female, it‚Äôs either about the same size or smaller.
JC: So there you go, now you know, frogs.
CB: And finally, we would be remiss without talking about the vocal sac because frogs and toads are most known, at least to me, for that great, great sound they make in the evening time in the American south and all over the world.
JC: Yeah. It‚Äôs pretty awesome. So you know, you‚Äôve seen pictures and video of a frog‚Äôs, their skin under their chin just suddenly turns into a huge bubble?
JC: So what they‚Äôre doing right then is they‚Äôre taking in a tremendous amount of air and they‚Äôre holding it in their air sac, right?
JC: And they‚Äôre moving it, keeping it in their air sac, they‚Äôre not releasing it, but they‚Äôre moving it around across their vocal chords. That‚Äôs what makes the ribbit sound or the croaking or the trilling sound.
JC: It‚Äôs pretty awesome. One of the reasons why they‚Äôre making those sounds, or at least one of the sounds, is they‚Äôre attracting a mate, right? They‚Äôre talking to one another, they‚Äôre saying, ‚ÄúHey, what do you think?‚Äù
CB: Yeah, and that sound can be everything from a croak to a ribbit to there‚Äôs this, I don‚Äôt know, there may be more than one species, but there‚Äôs this one I‚Äôve heard this summer that sounds, and I‚Äôve heard people call the police, because it sounds like a child that‚Äôs in danger.
JC: [Chuckles] Yeah, can you do an impression of it?
CB: No. I wish I could. It‚Äôs just super loud and it sounds like a child that‚Äôs hurt. It‚Äôs like a screaming sound.
JC: Oh, I‚Äôve not heard of that one.
CB: Oh, man. It‚Äôs crazy sounding.
CB: Yeah, I‚Äôll send you a link. I bet there‚Äôs a YouTube recording or something.
JC: It‚Äôs like peacocks going, ‚ÄúHeeeelp!‚Äù
CB: [Laughs] Yeah.
JC: It‚Äôs off-putting, isn‚Äôt it?
CB: I still say that to this day because of you.
CB: Because we have a neighborhood peacock that I‚Äôve talked about.
JC: So, Chuck, when frogs are making these mating calls, right?
JC: They‚Äôre saying, ‚ÄúHey baby, how‚Äôs it going?‚Äù And the frog might come over or the, the male frog might say, ‚ÄúI like your look. I‚Äôm gonna climb on top of you, how about that?‚Äù And there‚Äôs actually, because frogs are, in a lot of cases, not sexually dimorphic, like you can‚Äôt visually tell the difference between a male and a female frog of that species.
CB: Apparently, that extends not just to us humans but to frogs as well because there‚Äôs something called a release call to where if a male frog has mounted another male frog, the male frog that‚Äôs been mounted will have a release call saying like, ‚ÄúI‚Äôm a dude, buddy. Keep looking.‚Äù
CB: Yeah, actually, they‚Äôve actually recorded that sound in nature.
JC: Oh, yeah?
CB: And I think it‚Äôs something like, ‚ÄúWhoa, whoa, whoa, whoa!‚Äô
JC: [Laughs] Right.
JC: ‚ÄúI like you as a friend.‚Äù
CB: [Laughs] Yeah.
JC: So the frog will move on. It‚Äôs funny that they get confused just from looking as well and that it takes a reactive.
CB: Yeah. [Laughs]
JC: Process to handle that, you know?
CB: Yeah, it‚Äôs called the amplexus, which is the position that they‚Äôre in.
JC: Yeah, that‚Äôs the mounting position.
CB: Yeah, and the male literally gets on the back and clasps the forelegs around the lady frog‚Äôs middle.
CB: And they can stay there for days like that.
JC: However long it takes.
CB: Pretty much.
JC: It‚Äôs just a sensual seduction.
CB: [Laughs] Basically just waiting for the female to release her eggs. As far as reproduction goes, and this is something that we all learned about when we were little kids with frogs, with the tadpoles, we‚Äôll get into that, but the general rule of thumb with most is that they‚Äôre all sexual reproducers and all frogs and toads will be hatched from an egg.
JC: Right. Depending on how they come out, there‚Äôs big differences too like most‚Ä¶ Well, I don‚Äôt even want to say most; I saw somewhere like half of frogs come out fully formed, just super small.
CB: That‚Äôs adorable.
JC: I‚Äôll bet. The other, say, half come out as tadpoles and that‚Äôs the one that every little kid knows about. It‚Äôs frog reproductive biology, right?
CB: Yeah, and depending on the species, they can do crazy adaptive things. Like there‚Äôs one species that incubates, like the female frog clears out her belly and then incubates the eggs in its belly.
CB: For the whole time, and the frog is born out of her mouth essentially.