Short Stuff: Why do kangaroos hop?

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0:57Chuck Bryant:D-I-C.

1:02Chuck Bryant:Hey, and welcome to The Short Stuff. I'm Josh, and there's Chuck, and Jerry's here for Dave, and we're just hopping along, talking about kangaroos and how they hop.

1:11Josh Clark:That's right. I want to thank our old colleague, Kristen Conger, for writing this article from How Stuff Works back in the day.

1:18Chuck Bryant:And creator of Unladylike, the podcast, too.

1:22Josh Clark:As well as Jennifer Horton wrote another article that I used. Great, too. Remember Jennifer? And then I think the San Diego Zoo website and Nat Geo all pitched in for this one.

1:34Chuck Bryant:I thought this was a particularly well-researched short stuff, so I should have known that Jennifer Horton and Kristen Conger had something to do with it.

1:42Josh Clark:Yeah, so we're talking about kangaroos a little bit. Mainly going to get to how and why they hop, but we should start out by talking about the fact that roos are marsupials or pouched mammals because they have a marsupium, which is a little pouch where their little joeys develop.

2:00Chuck Bryant:Yeah, we talked, I think, a lot about this in the Naked Mole Rat episode, where essentially the marsupial fetus does not develop as long inside the body of the mom as it does inside the pouch. Essentially, at some point, it's what you would call born, but really it's just crawling out of the birth canal, outside into the world for a second, and into the pouch, and then the little Joey latches onto a nipple in there and the nipple grows three times in size, just like the Grinch's heart. And so the little Joey couldn't let go of the nipple, even if he or she wanted to, until they develop a little further.

2:41Chuck Bryant:It's quite ingenious. Hats off natural selection. That's a great one.

2:45Josh Clark:Yeah, that's maybe the fact of the podcast for me. That's kind of nutty.

2:48Chuck Bryant:Oh, I'm sorry I took that. I didn't realize that it was. No, no.

2:52Josh Clark:Do I have to always take the fact of the show?

2:54Chuck Bryant:I like to, you know.

2:56Josh Clark:I mean, I know it's in my contract and not yours, but I'm willing to give every now and then.

3:00Chuck Bryant:That's very generous of you. Thank you.

3:02Josh Clark:All right. So Australia is obviously what people, you know, what comes to mind when you think of marsupials in general because koalas and kangaroos. But we have done a great episode on the opossum, which live all over the place, especially North, Central and South America. But we're talking about kangaroos and wallabies here because they don't have four legs like our opossum friends. They have two big old feet and two littler arms.

3:29Chuck Bryant:Yeah, that's a great way to think about it. They don't have four legs. They have two legs and two arms. And it makes sense. Like if you've ever seen a kangaroo or you just bring one to mind, if you're capable of using your mind's eye, Um, they're, they're sitting on their feet and they're standing or sitting upright and their little almost, um, Titanica arms are just kind of hanging out there, not doing much of anything.

3:55Josh Clark:Yeah, except boxing, probably. The kangaroo, the first sightings apparently traced back to a Dutch merchant named Francisco Pelsert, who got shipwrecked off the coast of Australia in 1629. And about 150 years later, they were pretty well known throughout Europe. And by 1791, they had brought those things over to London, England.

4:18Chuck Bryant:Here's the fact of the podcast for me, Chuck.

4:20Josh Clark:Okay.

4:20Chuck Bryant:Can I take this one too, or should I tee you up? No, double up, baby. So the name kangaroo, the word, as far as anyone is able to say, we don't know for sure. It's apparently an aboriginal word for I don't know. Isn't that awesome? I don't know.

4:38Josh Clark:That's pretty funny. It is. Here's the deal, though, is kangaroos are the only large mammals to hop. And that's basically as like they're, you know, bunnies will hop a little bit. But the kangaroo moves around primarily by hopping. and I guess you wouldn't consider a bunny a large mammal anyway. Here's the deal. If you go back to 25 million years ago and look at the fossil record, they didn't hop because Australia was a rainforest at the time. So those kangaroos were climbing around for a long, long time. Yeah.

5:11Chuck Bryant:So they actually developed what ends up helping them hop long before they actually started to hop. We call that the fourth toe. if you look at a kangaroo's foot, you can see how it's hopping. And Chuck, I think I've kind of set us up for an ab break. And we're going to come back and finally talk about how kangaroos hop. What do you think? All right, let's do it.

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7:49Chuck Bryant:Okay, where I left off, Chuck, I was talking about the fourth toe, and this is the design element that allows the kangaroo to hop. because if you look at a kangaroo's foot, the first toe, looking at the kangaroo's foot from the inside of the foot outward, the first toe is pretty puny, might not even be there. The second and third toes, they're okay. They're like smallish and they each have a nail, but they seem to be fused together. So like webbed toes almost. Like my sister. Oh yeah, I didn't know she had webbed toes. Cool. Is she a fast swimmer?

8:22Josh Clark:That's what everyone always asks. It's just the second and third toe on one foot have always been stuck together.

8:28Chuck Bryant:But surely it would have to give you an advantage to some degree.

8:31Josh Clark:I don't know. I can't remember the last time I swam with her.

8:35Chuck Bryant:Well, next time you get a chance to race her and let me know how it turns out. All right. Finally, we get to the fourth toe. And the fourth toe is like just this massive beast of a toe. And it's in line with the leg bones of the kangaroo's legs. And this is where the actual hopping begins.

8:55Josh Clark:Yeah, that's an actual adaptation. And like you said, that preceded their ability to hop. So I'm not even sure what the deal is with why they adapted that to begin with. But I mean, maybe it's just because they went from rainforest to sort of dry, grassy plains and they needed to get around more. I don't know. learned it eventually. They do have a fit, though, we should mention. That provides a little bit of support. But if you look up, like, the foot of the hind leg, like, you know, from behind, they have these really, I mean, you can't see because it's on the inside, but they have these really strong elastic tendons that store energy up for those massive, massive jumps.

9:36Chuck Bryant:Yeah, like a spring. When they go downward, all of that tendon gets a bunch of energy, kinetic energy stored in it. And then when they bounce upward, it gets it's released and it can send them flying. Chuck, I had no idea how far they can hop and how fast. Did you?

9:54Josh Clark:Yeah, but it's always fun to relearn that, you know, because it's pretty astounding.

10:00Chuck Bryant:OK, so they can go up to 15 to 20 miles per hour. Yeah. And for those of you in Australia who don't No, that's about 24 to 32 kilometers per hour. That's fast. That's like golf cart speeds at top speeds even. That's faster than a golf cart.