Short Wave - Against All Odds, The Pumpkin Toadlet Is

Episode Date: July 5, 2022

Being small has its advantages ... and some limitations. One organism that intimately knows the pros and cons of being mini is the pumpkin toadlet. As an adult, the animal reaches merely the size of the skittle. At that scale, the frog's inner ear is so small, it's not fully functional. That means when the frog moves, it's haphazard and seems kind of drunk. And so today, with the help of Atlantic science writer Katie Wu, we investigate: If a frog can't jump well, is it still a frog?Read Katie's piece in The Atlantic, A Frog So Small, It Could Not Frog: https://bit.ly/3bydh1gWatch pumpkin toadlets poorly fling themselves around in this video from the Florida Museum: https://bit.ly/3bFAXRvSee pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. In the cloud forests of the mountains of Brazil, on the rainforest floor, there lives in itty-bitty orange critter called the pumpkin tootlet. And I should caveat this with the very important descriptor that it is not a proper toad, and a toad is really kind of a made-up thing anyway. But we don't need to get into that. This is Atlantic writer Katie Wu. And these things are ridiculously small, about a centimeter from nose to, butt or snout to vent, as you would say it more formally. Sout to vent, okay.

And you can imagine that it is about the size of a skiddle or a chickpea. And newborn pumpkin totlets come in at around half a skittal. They skip right over the whole tadpole thing, and that means that all along they have some of the tiniest inner ears in any animal. And like, big deal, right? Well, the inner ear is the home of the vestibular system. which is the thing responsible for keeping us balanced to moving smoothly? And so if you think about all of the important structures in your head that help you balance and help you not fall over when you're just walking from place to place,

or help you land a jump when you make a slight hop over the edge of a curb or something, that is all attributable to your vestibular system. And that can be traced back to your inner ear. And so when the inner ear is squished down to such a little. a tiny size, instead of the iconic, elegant leap and graceful landing of a frog. For the pumpkin toadlet, it's got the takeoff pretty down. It launches itself off of its high legs. But as soon as it really gets into the air, you see things start to just very rapidly fall apart. It starts to kind of twist and turn. You're kind of thinking, is there like

turbulence up there? It starts to spin or maybe cartwheel. And by the time, it's like flipping tail overhead, you're thinking this is not going to go well. And sure enough, it usually lands on its face or it belly flaps or it lands on its back. And you just see it kind of splayed there for several seconds after it lands like, oh, this again. It's like existential defeat. It feels like the last couple of years watching this frog. I think that's what kind of makes these little guys so relatable. And what really entertained me is, you know, I spoke to some researchers who have watched a lot of these frogs execute a lot of these very ill-fated jumps. And one of them told me, you know, they look almost grumpy mid-jump because it's almost like they know, like, it's not going to go well.

And, you know, for part of reporting this story, I sort of wondered, like, is this actually a tragedy and not a comedy? And I sort of lost myself to that question for a very long time. So today on the show, taking the leap, even when you know it's going to end badly. Life lessons from one of the clumsiest frogs out there about determination and playing to your strengths, however imperfect. I'm Aaron Scott, and you're listening to Shortwave, the Daily Science Podlet from NPR. Okay, Kitty, so really, what is the deal with this? Why does the pumpkin toadlet jump like a drunken ballerina? Yeah, it is a little bit sad, and it has everything to do with how ridiculously small these things are.

I mean, these are some of the smallest frogs we have ever found, and I may almost spoil the ending here, but this may be about as small as a frog can get because the jumping is so tragic here. But basically, we have to take a dive into their little heads. So there are these structures called the semi-circular canals, and it's this very, like, bendy straw-like structure that kind of loop-de-lops in your head. And there's a ton of fluid that moves through those canals. So we're picturing kind of like a water slide here. And along the canals, we have these hairs that when they're pushed around by fluid, those little hairs send signals to the brain saying, hey, movement's happening and just basically relaying that info. So if we don't get, fluid moving at the right speed in coordination with how, you know, the rest of your body is moving, the vestibular system is going to kind of fall apart. And so if you kind of imagine, like, the narrower those tubes get, the harder it is for the liquid to slosh around. And therein lies the problem for the pumpkin toadlet. It is so tiny that its vestibular tubes are so tiny that the fluid can't move adequately for it to sense its own movements and balance itself.

Wow. So, I mean, in a way, these toadlets have evolved to the point where a key part of their body just doesn't really function, which begs the question why? It's a fantastic question. And I don't actually think there is a perfect answer to this one. So, I mean, what happened with these frogs compared to you all the other frogs on the frog family tree is this process called miniaturization appropriately enough? You know, they shrunk way, way, way, way down. so that even in their adult stage, they're ridiculously tiny compared to other frogs. And it's thought that these frogs get an advantage from being so tiny because, you know, they can occupy new habitats. They don't need to eat as much to survive. They just don't need to go through the whole process of, like, finding a giant pond and laying eggs for their tadpoles to swim in.

They can just hang out in the leaf litter, you know, dead leaves all over the ground and occupy habitats that larger frogs cannot. And so that's allowed them to expand all over the place. And it's also incredibly easy to hide. They can just dart under some leaves. Some of them, some of them are brightly colored. But a lot of those brightly colored ones are also toxic. And so predators may see them be like, oh, that looks easy to catch, but I really don't want to catch it. And others are a deep leaf colored brown. And so it's really easy for them to blend in. Almost case in point, some of the researchers who study these frogs have a ridiculously hard time catching them. You know, two experts will spend like a full day digging around in the leaf litter and they'll catch one on average.

But it does come with this big cost. You can't just shrink forever and occupy new habitats forever. You've got to sort of pay the miniaturization tax. Miniaturization tax. I love that. And, you know, you think that a frog is a frog because of the way it leaps. Like that feels like that is central to the identity of a frog. Does this even count? Like, are these frogs? Yeah, this is where the story kind of gets existential, right? And like, hopping and jumping is like very much the frog raison d'etra. Did I see that right? Raisin de trot? I don't know. Raison. I don't know. We're not going to worry about it. We're going to get so many, so many comments for that. Yeah, but I think, you know, what is maybe more remarkable about this frog is it is so unfrog-like in its jumps and yet it still

manages to frog in some other ways like it is managing half the jump pretty well it still looks like a frog it still is a frog and it's kind of like you know it it gets by and you know i think it is a little unfortunate that we have stereotyped frogs to be these perfect jumpers, and that's certainly not to discount how good other frogs are at jumping. This one, that's not its strong suit, but I don't think that actually makes it any less frog. It's got other talents. It is smaller than most other frogs, and it manages to move around in its world with this ridiculously stunted vestibular system, which is an accomplishment in and of itself. So maybe to frog is not necessarily to land a jump, but to attempt it at all.

We are getting really deep into froggy philosophy today, which I guess brings us to the researchers. I mean, why are they studying and spending all this time trying to look at the jumping abilities of a little toadlet living in Brazil's Atlantic Forest? Yeah, I think there's a lot of reasons to study these little frogs in particular. I mean, certainly we haven't answered all the questions about miniaturization. What do they really gain by being so small? And is this actually the limit of how small frogs can get? You know, if we imagine something even smaller, it would basically have no vestibular system. Is that even possible? And how did they get to be this way? And, you know, another reason is frogs are so diverse and so, you know, unique in how they navigate the world. But they're also in a lot of danger. You know, there are a lot of frog species going extinct either because of, you know,

really dangerous fungi that have invaded their habitats or because their habitats are being destroyed by people or because of climate change. Pumpkin toadlets are actually a bunch of different species. And one researcher told me that they're so adapted to their little tiny environments that there's almost a different species on every mountain in this range. But they're fast disappearing because their world is changing so quickly. And so there's almost this race to study them and understand their derbiness before we lose them. Do you have any closing thoughts on the pumpkin toadlet that you would like to leave us with? Oh my goodness. I could stare at these little frogs all day and I'm constantly wondering, you know, what they're doing.

And I was very, very anxious. So I asked them, you know, do they get hurt? And they seem to be pretty plucky. And actually one researcher pointed out to me that, you know, even a kind of slightly failed jump is better than no jump. at all. They can jump a ridiculous distance, you know, many, many skittles worth of distance. And that still gets them from point A to point B-ish pretty quick, a lot faster than they could walk. Honestly, if I landed on my back that often, I wouldn't stop jumping entirely, but they still do it. It's a story of resilience, and I think that's beautiful. I love that so much. We need as many stories of resilience as we can get, particularly from the littlest amongst us. Katie Wu, it has been an absolute joy to talk totelets with you today. Thank you. This was so fun. I'm always so delighted to come back, as you know. So anytime.

Katie's article is titled A Frog So Small, It Could Not Frog. We'll link to it and the slow motion videos of the face planting toadlets in our episode notes. Today's episode was produced by Rebecca Ramirez, edited by Gabriel Spitzer and fact-checked by Rachel Carlson. Natasha Branch was our audio engineer. Giselle Grayson is our senior supervising editor, our programming heads, our senior director, Beth Donovan, and senior vice president, Anya Grunman. Special thanks to Juan Pablo Coloso Alonzo for his soundscape at the top of the episode. I'm Aaron Scott. Thanks for listening to Shortwave, The Daily Science Podcast, from NPR.

Okay, so honestly, toads are kind of a social construct. All toads are frogs, not all frogs. are toads, and we sometimes call certain frogs toads that don't belong to the so-called true toad family. So it's kind of fake. Kind of fake, and then a toadlet, which sounds even more fake. That just sounds like somebody wanted to be cute because these things are cute. Yeah, like, you're so tiny and you kind of look like a toad. You're a toadlet.