Short Stuff: Why do kangaroos hop?

Kangaroos are the only marsupial to hop, which is pretty weird. We'll investigate why. See omnystudio.com/listener https://omnystudio.com/listener for privacy information.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

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• 0:04Josh Clark?

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• 1:07Josh Clark?

  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.

• 1:15Speaker 02

  That's right. Want to thank our old colleague, Kristin Conger, for writing this article from How Stuff Works back in the day.

• 1:22Josh Clark?

  And creator of Unladylike, the podcast, too.

• 1:26Speaker 02

  As well as Jennifer Horton wrote another article that I used.

• 1:31Josh Clark?

  Great, too.

• 1:31Speaker 02

  Remember Jennifer? And then I think the San Diego Zoo website and Nat Geo all pitched in for this one.

• 1:39Josh Clark?

  I thought this was a particularly well researched short stuff, so I should have known that Jennifer Horton and Kristin Conger had something to do with it.

• 1:46Speaker 02

  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.

• 2:05Josh Clark?

  Yeah, we talked, I think, a lot about this in the naked mole rat episode where essentially like 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 on to 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. It's quite ingenious. Hats off, natural selection. That's a great one.

• 2:49Speaker 02

  Yeah, that's maybe the fact of the podcast for me. That's kind of nutty.

• 2:53Josh Clark?

  Oh, I'm sorry. I took that. I didn't realize that it was.

• 2:56Speaker 02

  What do I have to always take the fact of the show?

• 2:59Josh Clark?

  I like to, you know.

• 3:00Speaker 02

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

• 3:05Josh Clark?

  That's very generous of you. Thank you.

• 3:07Speaker 02

  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 opasim, 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 opasim friends. They have two big old feet and two little littler arms.

• 3:34Josh Clark?

  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, they're sitting on their feet and they're standing or sitting upright, and their little, almost Titanic arms are just kind of hanging out there, not doing much of anything.

• 3:59Speaker 02

  Yeah, except boxing, probably. The kangaroo, the first sightings, apparently traced back to a Dutch merchant named Francisco Pelser, 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.

• 4:22Josh Clark?

  Here's the fact of the podcast for me, Chuck.

• 4:24Speaker 02

  Okay.

• 4:25Josh Clark?

  Can I take this one too, or should I tee you up?

• 4:27Speaker 02

  No, double up, baby.

• 4:28Josh Clark?

  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.

• 4:42Speaker 02

  That's pretty funny.

• 4:44Josh Clark?

  It is.

• 4:45Speaker 02

  Here's the deal, though, is kangaroos are the only large mammals to hop. And that's basically as like their, 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.

• 5:14Josh Clark?

  Yeah. So they, 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, how it's hopping. And Chuck, I think I've kind of set us up for an ad break. And we're going to come back and finally talk about how kangaroos hop. What do you think?

• 5:37Speaker 02

  All right, let's do it.

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• 8:21Josh Clark?

  Okay, where I left off Chuck, I was talking about the fourth toe and this is the, this is the design element that allows the kangaroo to hop. Because if you look at a kangaroo's foot, the first toe, uh, 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 to like web toes almost.

• 8:48Speaker 02

  Like my sister.

• 8:48Josh Clark?

  Then when you, you get, oh yeah, I didn't know she had web toes. Cool. Uh, is she a fast swimmer?

• 8:54Speaker 02

  Nah, that's what everyone always asks. It's just the, the second, third toe on one foot are always been stuck together.

• 9:00Josh Clark?

  But surely it would have to give you an advantage to some degree.

• 9:03Speaker 02

  I don't know. I can't remember the last time I swam with her.

• 9:07Josh Clark?

  Well, next time you get a chance to register and let me know how it turns out.

• 9:10Speaker 02

  All right.

• 9:12Josh Clark?

  Uh, finally we get to the fourth toe and the fourth toe is like this, this massive beast of a toe and it's in line with the, um, leg bones of the kangaroo's legs. And this is where the actual hopping begins.

• 9:27Speaker 02

  Yeah, that's an actual adaptation. Uh, 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, um, I mean, maybe it's just because they went from rainforest to sort of dry, grassy plains and they needed to get around more.

• 9:44Josh Clark?

  I don't know.

• 9:45Speaker 02

  Learned it eventually. Um, they do have a fit though, we should mention, uh, that's provides a little bit of support. Uh, but if you look up, uh, like the, the foot of the hind leg, like, you know, from behind, um, they have these really, I mean, you can't see it because it's on the inside, but they have these really strong elastic tendons that store energy up for those massive, massive jumps.

• 10:08Josh Clark?

  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, um, they can hop and how fast. Did you?

• 10:26Speaker 02

  Uh, yeah, but it's always fun to relearn that, you know, cause it's pretty astounding.

• 10:32Josh Clark?

  Okay, so they can go up to 15 to 20 miles per hour.

• 10:35Speaker 02

  Yeah.

• 10:36Josh Clark?

  And for those of you in Australia who don't know, that's about 24 to 32 kilometers per hour. That's fast. That's like golf cart speeds, at top speeds even.

• 10:47Speaker 02

  That's faster than a golf cart, yeah.

• 10:49Josh Clark?

  And then it can propel itself about 25 feet forward, almost seven or more than seven and a half meters, and six feet high.

• 10:57Speaker 02

  Yeah.

• 10:57Josh Clark?

  Nearly two meters high. And so it could jump right over either of us, Chuck.

• 11:01Speaker 02

  Yeah, absolutely. Uh, I mean, you're taller than I am, so you might get your forehead grazed.

• 11:07Josh Clark?

  It could just barely clear me. I'm five foot 11 and a half, if I'm fully honest.

• 11:12Speaker 02

  Yeah, they would look at me and just be like, no problem, shorty.

• 11:17Josh Clark?

  They'd just free willy right over you.

• 11:19Speaker 02

  I used to be 5'10". Now I'm more like 5'9". I'm shrinking, as we all are.

• 11:23Josh Clark?

  Yeah, what is up with that?

• 11:24Speaker 02

  You shrink, you know?

• 11:26Josh Clark?

  But I mean, does that mean our vertebrae are fusing together, or like our knees are getting shorter? Have we compacted the shin bones in our legs and that's what's doing it? It doesn't make any sense to me.

• 11:37Speaker 02

  Well, we should do an episode, like a shorty maybe, on the shrinking as you age, because that's definitely a thing. That's why, like, you see an old man that has these giant ears. They didn't always look that way.

• 11:47Josh Clark?

  Oh, I didn't know that.

• 11:48Speaker 02

  Yeah.

• 11:49Josh Clark?

  Wow, what a development.

• 11:52Speaker 02

  All right, so back to the kangaroo. We need to talk about their tails a little bit, because they have those huge tails that act as a counterbalance to the hind feet. So if you look at a kangaroo hop, that tail moves down, like in midair, that tail is moving down to meet kind of where the feet are. And when they land, the tail raises, so it kind of just does this little opposite motion to balance everything out.

• 12:14Josh Clark?

  And it makes a really satisfying boring sound.

• 12:17Speaker 02

  Oh, of course.

• 12:18Josh Clark?

  So what's great about this, you said that the kangaroo is the only land animal that, or an only large mammal that hops. And the reason why it hops is because it's actually a tremendous adaptation for moving quickly across land in a really efficient manner. Because the way that the kangaroo is built,

• 12:42Josh Clark?

  the faster they hop, the less energy they have to expend. It's a pretty beautiful system.

• 12:48Speaker 02

  Yeah, it's pretty crazy. And one of the most efficient travelers in the animal kingdom overall, you know, that, like you said, they had that great range. And part of what's going on with their efficiency is is they have a like when they're bending down to jump and then leaping up, that's contracting and suppressing their respiratory system, which actually is like makes it more efficient. It makes those stomach muscles contract and expand and just forces air in and out without like having to do so, you know, by using your own energy.

• 13:21Josh Clark?

  Yeah, and they also have to use less muscle energy in their legs because when they jump really far, high and fast, when they land, those super elastic tendons that that help them hop, just contract even further. And that means that they expand or sprawling, I think is the technical term, even further. So when they get going, they really can just, they can just keep going a while. They're also their heart is really attuned to this kind of endurance workout, right?

• 13:52Speaker 02

  Yeah.

• 13:52Josh Clark?

  It's when they're not going fast, when they're just kind of hopping from place to place and grazing, that's when it's harder. And they have to end up using their tail to kind of balance themselves is basically like a, well, a third foot.

• 14:05Speaker 02

  Yeah. Yeah. Why does it say fifth in here? That's so weird.

• 14:10Josh Clark?

  I know, because they specifically said that their two front

• 14:14Speaker 02

  Yeah.

• 14:14Josh Clark?

  arms, you know?

• 14:16Speaker 02

  Hey, well, maybe I'll get in touch with Connor. Gives me a good reason to get in touch with her. Say, what the hell did you mean with this fifth leg thing all those years ago?

• 14:24Josh Clark?

  You're gonna ruin her week.

• 14:26Speaker 02

  She's like, who is this?

• 14:27Josh Clark?

  Right?

• 14:29Speaker 02

  Uh, I guess we'll close quickly just on a little, you know, I mentioned the wallaby, the slight differences between the wallaby and the roo. Mainly, it's the kangaroo is just a lot bigger. They have a lot more length between their ankles and their knees and they're just taller. They can be like eight feet tall, whereas a wallaby is maybe like three feet, a little over.

• 14:49Josh Clark?

  Can you really say it any other way than that?

• 14:51Speaker 02

  I don't think so.

• 14:52Josh Clark?

  I mean, why would you anyway?

• 14:54Speaker 02

  Yeah.

• 14:55Josh Clark?

  This is probably long after your wheelhouse, but did you ever watch Rocco's Modern Life?

• 15:00Speaker 02

  Never heard of it.

• 15:01Josh Clark?

  It's a great cartoon. Yeah, it's a cute little cartoon. It was on Nickelodeon. And Rocco was a wallaby.

• 15:09Speaker 02

  Oh, nice.

• 15:11Josh Clark?

  Did you ever watch Darkwing Duck?

• 15:13Speaker 02

  Never heard of it.

• 15:13Josh Clark?

  No, that's not it. What was the duck with Jason Alexander as the duck?

• 15:19Speaker 02

  Oh, I don't think I, I don't think I know of such a show.

• 15:22Josh Clark?

  It was like a raunchy comp, like superhero duck show. That was pretty good. Whatever the name of it was, look it up. Jason Alexander George from Seinfeld played the, the main duck.

• 15:34Speaker 02

  Oh, wow. That was a good one, too?

• 15:36Josh Clark?

  Yeah, I think Darkwing Duck is like a DuckTales spinoff. That's not what I'm talking about.

• 15:41Speaker 02

  All right. Well, I mean, if we're recommending animated shows, I might as well. And we're in Australia. I gotta recommend Bluey again. Still watch that.

• 15:48Josh Clark?

  Okay, I never watched that one.

• 15:49Speaker 02

  Yeah.

• 15:50Josh Clark?

  So, so stepping out of the animated shows, but continuing with the recommendations.

• 15:55Speaker 02

  Oh, boy, here we go.

• 15:57Josh Clark?

  The Jake Gyllenhaal movie Enemy last night.

• 15:59Speaker 02

  Oh, yeah.

• 16:00Josh Clark?

  It was Denis Villeneuve. Have you seen it?

• 16:05Speaker 02

  I saw it back, back then.

• 16:07Josh Clark?

  Man, it is a good movie.

• 16:09Speaker 02

  Yeah, crazy ending.

• 16:11Josh Clark?

  Yes, but so like it was one of those movies that I was like just sitting there thinking about it afterward.

• 16:17Speaker 02

  Yeah, yeah.

• 16:17Josh Clark?

  And so I love those because if you go look them up online, there are people who have like given great thought to explaining these things. And I found, I think on Slash Film, a really great explanation of what was going on. But be forewarned, if you watch Enemy, you may regret reading the explanation of it. It's almost, to me, it was better before I knew and I just had, had to accept it on its own terms.

• 16:45Speaker 02

  Yeah, love that movie.

• 16:47Josh Clark?

  All right. Well, that's it for Enemy and that's it for obviously Kangaroo Hopping, right?

• 16:52Speaker 02

  That's right.

• 16:53Josh Clark?

  Short stuff is that.

• 16:57Speaker 00

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