Tracking collars reveal just how extreme a wild cheetah’s movements can be | Hacker News Reader

Tracking collars reveal just how extreme a wild cheetah’s movements can be

nationalgeographic.com

110 pointscurtis42 comments

The stride length is mind blowing. 6-7 meters (21 feet).

World record long jump is 8.95 m.

Longer sure, but the one is a crowning achievement while the other is every step...

I assume you mean the world record long jump for humans is 8.95m. Why would that matter to cheetahs? Wrestle an elephant, and you'll lose.

He's pointing out that what is exceptional for us is mundane for cheetahs.

"Cheetahs accomplish this with leg and back muscles that make up half its body weight. These contract at such high speeds that each kilogram of muscle generates 100 watts of power. For comparison, greyhounds produce just 60 watts with the same amount of muscle, horses manage just 30 watts, and Usain Bolt can produce just 25. With these powerful muscles, a cheetah can speed up or slow down by up to 9 mph in a single stride. The cat is like a sports car that always runs on second gear."

This is astounding. 100 W per kilogram of muscle. Average cheetah weight is around 50 kg (From their Wikipedia page). Considering their muscle weight is around 25 kG, their power consumption is around 2500 Watts.This seems very efficient to me, considering they can sustain lower speeds for longter time if required.

Nature is crazy efficient.

Efficient where it has to be.

Plants only convert between 3 and 6 percent of solar energy. https://en.m.wikipedia.org/wiki/Photosynthetic_efficiency

Cheetahs get about 90% elastic recovery from each stride; humans max out around 70%. Most robots, 0%, which has been a long-standing legged mobile robot problem. It's one reason those hydraulic Boston Dynamics machines needed way too much power.

It sounds like their power output is 100 watts per kilogram - it doesn't say anything about how much energy they had to consume to provide that. It's unlikely that they are as efficient at high speeds as they are at lower speeds.

OK, that gets a WOW. The article's discussion of some of the thought that has gone into the collar technology (P2P assessment of when to increase the sensor rate, such as during a hunt, for example) was really interesting.

it's so amazing how level they can keep their heads while the rest of their bodies contort so quickly and graciously.

coincidentally, i worked with john bertram (mentioned in the article) many moons ago on gibbon locomotion. go watch gibbons navigate the 3D space of a forest canopy at top speed. it's jaw-dropping.

https://www.youtube.com/watch?v=fPXkUXXFoCw indeed they are agile

One of my dreams for virtual reality in the future is a setup that would do justice to being put in an animal's perspective as it moved around.

A peregrine falcon's dive, a cheetah's sprint, and more would all be mind blowing if one were sufficiently immersed.

it's so amazing how level they can keep their heads while the rest of their bodies contort so quickly and graciously.

That really caught my eye too, it's incredible.

That video is unbelievable. I have always fascinated by cheetahs and their necks. But this just takes it to the next level.

Thanks for sharing this! I have nothing meaningful to add other than that I am awestruck by this video.

There’s something ancient and royal about the face of the cheetah, in slow motion it’s simply majestic.

The music adds to the experience for sure, i found myself wiping my eyes halfway through.

0-60mph in 3 seconds or just 3 strides. [1] Unbelievable.

[1] https://www.youtube.com/watch?v=V8vejjVgIHg

GPS's are not that accurate, you can't use it to measure top speed of humans. Anyone know how much off GPS's can be ? I guess in 10 m/s they can be +- 1 m/s off for good quality and all down to +- 50% for a bad GPS. Anyone know how exact accelerometers are ?

> 64 miles per hour (29 metres per second)

my units’ sense just got violated...

They prey they hunt is also very fast

I would make a lousy cheetah

Amazing use of different technologies. Being able to overlay the gos data on details maps is just so cool!

The data from the collars is astonishing, not least when Wilson overlays it onto maps of the terrain captured through Google Earth. In one hunt, he can see one of the cheetahs using a termite mound to bank!

The Matrix: Now It’s Cheetahs

I also wonder what it feels like to run so fast? It can be kind of exciting to ride a bike at half that speed, but to run, to have thst connection with the ground must make it even more intense. I realize that the cheetah doesn’t feel this of course, but for a human!

> I realize that the cheetah doesn’t feel this of course

And why would that be? That's a very XIX century view of animal brains.

Is a cheetah focused on the hunt, when it accelerates like that? Of course. Does it enjoy it, does it "feel" the intensity? At some level, it probably does. Does a cheetah run for recreational purposes just to enjoy the feeling? Probably not, because it's incredibily tiring and they struggle to eat enough as it is.

I think they would run sometimes out of excitement or jubilation. I'm thinking of the videos of cows doing exactly that when let out of their barn for the first time in Springtime.

Had to look for a video of cows doing this. Quite funny to see their excitement to finally be out in the open.

https://www.youtube.com/watch?v=huT5__BqY_U

That's quite a good one. There are lots of these videos, in some places crowds attend to share the occasion with the cattle - nice event :)

https://www.youtube.com/watch?v=wNCQZWiBJBg

Most mammals play.

When I was cycling in the US in 2014 on my recumbent tricycle (so I’m less than a metre off the ground, and feeling the surface of the road more), I estimated that I got to about 90km/h as I approached Mojave—and it was only that slow because I was using the brakes somewhat, otherwise I’m confident I would have hit 100km/h. (I do wish I had been doing GPX logging at the time so I’d have proof of how fast I was going. Ah well.)

It was fun. Sure, I was consciously aware that if my trike failed I’d be dead, p ≥ 0.95 (that’s why I was using the brakes at all), but it was nonetheless super fun. And very blowy indeed.

There’s just nothing like it in Australia; it’s all flat here by comparison, so you don’t get the chance to just relax and glide along at 60–100km/h for ten or fifteen kilometres (to say nothing of the next thirty kilometres where I was very easily able to maintain 50km/h except for when I got stopped for roadworks).

I've gone 51 mph (82 kph) on an upright road bike going down a 17% grade. Terrifying. 60kph is fun but scary. But sprinting is really exciting. It is a full effort acceleration from stand still to as fast as you can spin. It feels really intense and crazy with the bike flexing and twisting from the effort. It only lasts a few seconds but those feel like peak experience. I imagine the cheetah feels something similar.

Somewhere around 80km/h on a fairly-long-and-steep-by-Australian-standards hill is the most I’ve done on an upright road bike, but that wasn’t with pedalling by the top speeds. Trying to accelerate by pedalling at those speeds on a bicycle is very dangerous. You can only sanely manage it if your gearing is way higher than the typical road bike has, and the vehicle is well-maintained so that you can be confident you won’t have any slipping chain (an easy recipe for disaster in such a situation).

In the anecdote I started this thread with, I was on a trike which is inherently stable, so it was much safer for me; and I was just rolling down it rather than pedalling—and I stayed at the top speed for at least a minute or two, because the mountain was that long and steep! (It had taken a long time to get up the other side of the hill, perhaps an hour or an hour and a half, I don’t recall precisely. Fortunately I got this payoff!)

Yep, similar to my experience. I came to the conclusion that doing so on a road bike with all but a flimsy helmet for protection is nuts.

I've been on a Superbike on Phillip Island Circuit cornering at maybe ~200km/h, which was even more mind bending but also felt marginally safer due to proper leathers and full face helmet, and removal of random traffic factors + using machinery designed for that purpose.

I cycle every day in the city and so in certain areas it's common to cross paths with pigeons or other birds. I've noticed that regardless of whether the bird was walking or already in flight, if their path is perpendicular to mine they almost invariably adjust to cross in front of me only a few inches off the ground. Sometimes this increases the risk of collision, as veering left, right, or simply going up would take them out of my path completely. Thinking about it on a recent ride I wondered if part of the reason they get so close to the ground is to feel faster– either psychologically, or in an attempt to gauge their own speed relative to an incoming object.

(I've never ridden a recumbent tricycle but can imagine the effect of being closer to the ground. Crouching on a skateboard or leaning in on a bicycle or motorcycle all change my perception even before an actual change in speed.)

My father is a keen birdwatcher, and he told me that birds go low to the ground as a defence mechanism against birds of prey - the bird of prey cannot catch the swooping bird without crashing into the ground. I suppose they might do similar with cars and bikes if they feel threatened as an evolutionary misfiring.

I think they are probably just naturally (to them) trading a slight amount of potential energy (altitude) for increased velocity - after all they'd rather be one inch past your front wheel at the crossing point than one inch on the other side.

This is very likely. There's also the chance they're taking advantage of some portion of the ground effect ( https://en.wikipedia.org/wiki/Ground_effect_(aerodynamics) ), thereby allowing themselves to increase their speed even further.

What configuration tricyle? Tadpole?

It’s a Greenspeed GT3, which is tadpole. I wouldn’t allow a delta I was on to get that fast!

Still impressive. Be careful with any steering at that speed, you can flip over pdq.

I certainly wouldn't want to be on a delta trike at 90kph.

> I realize that the cheetah doesn’t feel this of course, but for a human!

Maybe not as intensely as a human, because that speed is normal to them, but they probably feel the same basic sensation. Most cats like sprinting around for fun occasionally.

I imagine it's a similar feeling for humans when you first ride a big-bore motorbike. The feeling is far less like driving a car and more, in a way, like running very fast.

I managed to make a little more than 100km/h while skiing. It is terrifying and incredibly fun at the same time. The sheer inertia is very dangerous though, even in snow; so just thinking about having to put a clawed paw in firm soil and do sudden turns and stops... while looking at your prey and not to the floor... while barefoot... that sure is a recipe for at LEAST some sprained ankle. Cheetahs are awesome!

I managed 85km/h on a somewhat twisty but steep downhill road of a mountain/hill in NSW, Aus on my road bike.

That was nuts and whilst exhilarating I'm not doing it again.

These cats are going faster than that and manoeuvering under their own power. Simply amazing.

My top rollerblading speed was 24mph back in highschool (going downhill for extra acceleration, and measuring using one of those side-of-the-road "you are going this fast" stands meant for cars), and yeah, the direct contact with the ground does make for a much different and more exhilarating feel than cycling.

Cheetahs don't maintain constant contact with the ground like a rollerblader, though. They practically fly just above it, all four feet leaving the ground at once twice per stride. It's less like a run as you and I know it, and more like a series of bounding leaps, which probably makes it all the more exciting.

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