How Cats Are Able to Land on All Four Feet

December 28, 2008 10:32 PM

Cats have a seemingly unique ability, a 'righting reflex', to orient themselves in a fall allowing them to avoid many injuries and land on all four feet. It is this ability that helps cats to parachute safely into Borneo and survive falls from the 38th floor of a skyscraper (although falls from lower levels can be more serious given that it takes some time for the cat to right itself). Here's how it works. Here's a video of the reflex in action.
posted by Effigy2000 (68 comments total)

Animal experts say that this instinct is observable in kittens as young as three to four weeks, and is fully developed by the age of seven weeks.

How many two-week-old kittens did they have to drop to figure this out?
posted by Knappster at 10:46 PM on December 28, 2008 [13 favorites]

Just don't strap a piece of buttered toast to your cat before he/she goes base jumping or you'll have to deal with the Buttered Cat Paradox.
posted by amyms at 10:48 PM on December 28, 2008 [5 favorites]

Ah, there is such grace in the motion of a falling cat.

Difficult to believe these are the same animals which will happily roll right off counter tops when petted or collide with literally everything while chasing collimated light... or stand in the middle of a plate of tuna fish.
posted by Kikkoman at 10:55 PM on December 28, 2008 [11 favorites]

Knappster: How many two-week-old kittens did they have to drop to figure this out?"

None. The kittens were just showing off.

Kikkoman: "Ah, there is such grace in the motion of a falling cat. Difficult to believe these are the same animals which will happily roll right off counter tops when petted or collide with literally everything while chasing collimated light... or stand in the middle of a plate of tuna fish."

They meant to do all of that, Kikkoman. The fact that you find it amusing is certainly of no concern to your four legged master.
posted by Effigy2000 at 11:00 PM on December 28, 2008 [7 favorites]

In the video, at 2:57, you can see the fingertips of a human hand dropping the cat. I thought that was kind of funny, that somebody was just dropping this cat, over and over.
posted by Corduroy at 11:26 PM on December 28, 2008 [3 favorites]

Thanks for the post.
posted by Corduroy at 11:26 PM on December 28, 2008

That video was funnier than I was expecting.
posted by dead cousin ted at 11:30 PM on December 28, 2008

Thanks for inspiring me to Google for a video of a cat falling in a weightless environment.
posted by jaimev at 11:33 PM on December 28, 2008 [9 favorites]

your four legged master.

Dogs have owners, cats have staff.
posted by Pope Guilty at 11:36 PM on December 28, 2008 [3 favorites]

Thanks for inspiring me to Google for a video of a cat falling in a weightless environment.

I expected this to be hilarious but I really felt for the poor kitty; it looked like it was going to hurt itself from thrashing around so hard.
posted by Pope Guilty at 11:39 PM on December 28, 2008 [2 favorites]

Better look up/Above the trees/Not raining water/But falling kitties/Burma Save
posted by fallingbadgers at 11:42 PM on December 28, 2008

Thanks for inspiring me to Google for a video of a cat falling in a weightless environment.

The jumpsuits and the 80s hair make it seem like some horrible ending-bad-for-kitty scene from V.
posted by Artw at 11:55 PM on December 28, 2008 [2 favorites]

Confused weightless dog.

Terrified skydiving cat.

Seemingly nonplussed skydiving dog .

Questionable dog BASE-jumping .
posted by PareidoliaticBoy at 12:36 AM on December 29, 2008

Thanks for inspiring me to Google for a video of a cat falling in a weightless environment.

Why was he throwing the cat against the wall?
posted by null terminated at 12:41 AM on December 29, 2008 [2 favorites]

Seemingly nonplussed skydiving dog .

Nonplussed?
posted by null terminated at 12:44 AM on December 29, 2008

Yeah, well, I'm not sure I'm buyin' that whole enthusiastic verdict his owners' are comin' up with; their pretty questionable dog interpretation after Milo's rather feeble bark notwithstanding.

I'm thinkin' he's more perplexed than anything else.
posted by PareidoliaticBoy at 12:53 AM on December 29, 2008

Scrappy little terrier types like that are up for anything. I bet he rides in a motorcycle sidecar too.
posted by Artw at 12:57 AM on December 29, 2008

"animals with these characteristics are fluffy and have a high drag coefficient giving them a greater chance of surviving these falls"

So, I lose some weight and rent a Big Bird costume.
I think I've figured out how to never wait for the down elevator again.
posted by Dipsomaniac at 1:06 AM on December 29, 2008 [1 favorite]

Long-hair and short-hair breeds fall at the same rate in a vacuum.
posted by Artw at 1:10 AM on December 29, 2008

Ize in yer airspace ritin myself.

Iz we dere yet?
posted by fourcheesemac at 2:59 AM on December 29, 2008

"Operation Cat Drop" reads like a bullshit e-mail forward, and googling reveals the story repeated over-and-over without any legitimate sources. I even found a website for a book (an academic publication published by a real press) which repeats it as true without question.

Snopes doesn't address it, but another book (Tales with Tails by Kevin Stauss, p. 40) says:

This is a wonderful story. Unfortunately it isn't true. Stories like "Parachuting Cats into Borneo" are a kind of environmental urban legend. Some of these stories are so good that they spread like wildfire in the environmental education community . . .

The author goes on to tell how he first heard the story and investigated its truth (or lack of).
posted by D.C. at 3:14 AM on December 29, 2008 [2 favorites]

It's actually not true that cats take time to right themselves when falling: they need only a few seconds, as any cat owner can attest. That's not the reason why cats tend to survive falls of several levels better than only a few floors. The fact is that cats reflexively tense when they right themselves, and this bracing causes severe injury when you start getting into multiple stories. However, when they fall for even longer lengths of time, they have time to relax that instinctive tensing, allowing them to "bounce", so to speak (there's obviously a point at which this no longer helps). It's kind of like how drunk people always are always surviving crazy tall falls by virtue of being drunk.
posted by internet!Hannah at 3:30 AM on December 29, 2008 [2 favorites]

And on watching the cat video with the sound on, I see they said exactly what I did.
posted by internet!Hannah at 3:34 AM on December 29, 2008

Why was he throwing the cat against the wall?

That's the only way to disentangle yourself from a sharpened cat.
posted by DU at 4:20 AM on December 29, 2008 [3 favorites]

This was addressed by The Straight Dope and the answer can be found online, but you may want to think about this puzzler: You release the cat, upside down, with zero angular momentum. No angular momentum is added during free fall. It lands right side up. How?
posted by DU at 4:29 AM on December 29, 2008

Drag caused by airflow is controlled by the cat to induce and then stop rotation.
posted by squorch at 6:34 AM on December 29, 2008

Nope, not air friction. This maneuver could be performed by a cat in a spacesuit.
posted by DU at 6:36 AM on December 29, 2008

I want to believe in Operation Cat Drop. There is a web site with a fact-revised version of the story available with references. Choice quote:

“Cat drop” did occur to replenish a cat population in Borneo. The only written evidence for this states that the drop occurred in one remote village of northern Borneo, Bario, in the Malaysian state of Sarawak. A number in excess of 20 cats were dropped in a special container designed to withstand the parachute drop by a large transport plane operated by the Royal Air Force.

posted by Free word order! at 6:41 AM on December 29, 2008

Oh, the evidence: page from RAF Operations Record, Borneo, 1960 (from catdrop.com). "All cats safe and much appreciated (?)"
posted by Free word order! at 6:48 AM on December 29, 2008

It lands right side up. How?

It twists, and then sticks one leg out, and that works because of, well...

Differential centripetal force?
The Coriolis effect?
Precession?

Actually, Heisenberg's Uncertainty Principle says you can never determine whether any given cat is the right way up at a particular moment when dropped. Or is it that you can't tell whether it's dead when it's in a box?

OK, lead weights in its feet?
posted by Phanx at 6:56 AM on December 29, 2008

No, not lead weights, coriolis or precession. I don't know what "differential centripetal force" means.

This maneuver could, I think, be used by a space-faring cat in a weightless, airless environment. (I say, "I think", because I'm pretty sure the math would work out, but in practice it may require a small damping effect from air friction.)
posted by DU at 7:02 AM on December 29, 2008

there's obviously a point at which this no longer helps

Actually if you believe the study about cats surviving at a higher rate from higher levels, there is no point where it no longer helps. Cats can easily reach terminal velocity (the speed at which air resistance cancels out the acceleration of gravity) from a tall building, so being dropped from a roof or 10,000 feet in the air shouldn't really matter in terms of the speed of the cat when it hits the ground.
posted by burnmp3s at 7:14 AM on December 29, 2008

...there is no point where it no longer helps.

Some cats may need special heat shielding for this.
posted by DU at 7:18 AM on December 29, 2008 [4 favorites]

I've definitely seen my cat fall off my desk onto her butt. I'm not signing her up for Operation Cat Drop.
posted by grapefruitmoon at 7:45 AM on December 29, 2008 [1 favorite]

DU- The cat doesn't need to keep its angular momentum; it just needs to be in a particular orientation, ASAP. If it were possible to "borrow" angular momentum (turning for a bit) and then "pay it back" (stopping your turning) then that would do the trick (you would have changed your orientation without ending up with angular momentum that you didn't start with).

Conservation of momentum being what it is, we can't borrow over time. But depending on how we're built, we might be able to "borrow over space"- inducing equal and opposing angular momenta in different parts of ourselves. If one of those rotating body parts hits the limit of its joint(s) first, it can start to turn the torso of the cat. Then, the counter-rotating body part hits the limit of its joint, and stops the body's turning. The cat has thus turned without ending up with net angular momentum.

Without any actual research or cat-based-knowledge on my part, that or something like it is my guess.
posted by Jpfed at 7:45 AM on December 29, 2008

Some cats may need special heat shielding for this.

I wouldn't suggest dropping a cat from space or near-space distances. Aside from the atmospheric reentry problem, you have to deal with extremely low temperatures, low pressure, lack of oxygen, increased chance of fatal spins due to decreased air resistance, etc. You would at the very least need a fully pressurized cat spacesuit, which would most likely be adorable but extremely difficult to convince the cat to wear.
posted by burnmp3s at 8:26 AM on December 29, 2008 [4 favorites]

...inducing equal and opposing angular momenta in different parts of ourselves.

This much is correct. The sentences that follow weren't too clear to me, so I'll (possibly re-)iterate: The cat spreads out its back legs and pulls in the front and counter-rotates. The front can turn 180 (actually 190, say, see below) degrees while the back only turns, say, -10 degrees and the angular momentum is still zero. Then pull in the back and spread out the front and rotate the other direction. The front now turns back, say, -10 degrees (total of 180) and the back turns back, say, 190 (total 180). Result: flipped cat.

(Disclaimer: I did not actually know all the details of this until I search prior to posting the puzzle.)

Some satellites and spaceships do attitude control with rotating internal gyros. I wonder if any do it via the cat method of shifting moments of inertia around and rotating the body itself. Alternatively, some rotifers and other animalcules have rotating body parts--why don't any forms of life have gyroscopic attitude control? Oh wait--because the rotating Earth screws everything up. DAMN YOU ROTATING EARTH!
posted by DU at 8:28 AM on December 29, 2008

You release the cat, upside down, with zero angular momentum. No angular momentum is added during free fall. It lands right side up. How?
posted by DU at 4:29 AM on December 29 [+] [!]

I just did this to my cat off the balcony. I don't know the physics-what-cha-ma-call-its, but it works!! Snuffy landed on her feet!
posted by every_one_needs_a_hug_sometimes at 8:39 AM on December 29, 2008

Good lord, I've heard about this.

CAT JUGGLING!
posted by Astro Zombie at 8:45 AM on December 29, 2008

Well, the good news is Snowball did land on her feet. The bad news is the declawing debate is sort of moot at this point.
posted by Pollomacho at 8:57 AM on December 29, 2008

grapefruitmoon : I've definitely seen my cat fall off my desk onto her butt.

Did she then give you that look? The one that all at once said "You didn't see that", "I meant to do that", and "Somehow, this is all your fault!"

Because it was your fault you know. The mere act of you observing was enough to throw the universe out of whack enough for you cat to lose her bearings. It's the only possible explanation for when something like this happens.

Or so my kitty told me after I found her gracelessly upended off the side of the bed one day.
posted by quin at 9:03 AM on December 29, 2008 [2 favorites]

Yeah, The Straight Dope questions the data used to support the notion that cats falling from greater heights sustain fewer injuries.

The potential flaw is this: the study was based only on cats that were brought into the hospital. Clearly dead cats, your basic fell-20-stories-and-looks-like-it-came-out-of-a-can-of-Spam cats, go to the Dumpster, not the emergency room. This may skew the statistics and make falls from great distances look safer than they are.
posted by nobodyyouknow at 9:27 AM on December 29, 2008

Cats falling in slow motion should be some kind of screensaver.
posted by six-or-six-thirty at 9:31 AM on December 29, 2008

Was I the only one waiting (and hoping) for a little kittie poop to come floating out in the zero gravity vid?
posted by scarello at 9:43 AM on December 29, 2008

Some satellites and spaceships do attitude control with rotating internal gyros. I wonder if any do it via the cat method of shifting moments of inertia around and rotating the body itself.

For example the Hubble Space Telescope uses momentum (reaction) wheels in order to do precise positioning and tracking of celestial objects. The reaction wheel is a heavy spinning disk. In order to turn, the satellite uses a small solar powered electric motor to either speed up or slow down the momentum wheel. The motor would be the equivalent of the cat's muscles. When the motor spins up the momentum wheel, the satellite spins in the opposite direction and continues rotating until the motor slows down the momentum wheel to its previous RPM. The satellite stops its rotation, pointing in a new direction and the momentum wheel is back to the original speed. At no time during this procedure does total angular momentum change, and of course it could not since there is no external force applied. The same works for the cat, even though, one presumes, it knows nothing of Newton's physics.

The cool part is that the cat instinctively shifts angular momentum back and forth between its head and its tail by extending and retracting its legs and tail, just like the motor shifts momentum back and forth between the reaction wheel and the satellite.
posted by JackFlash at 9:46 AM on December 29, 2008 [1 favorite]

The same works for the cat, even though, one presumes, it knows nothing of Newton's physics.

Someone could certainly presume that, though I'm convinced they'd be wrong. I'm fairly convinced that cats have us all well fooled, and they are actually advanced physicists carefully studying the universe around them.

Why else would they have such an interest in the flight of a bird, or the bounce of a ball of string, or the angular velocity of a bottlecap flying across the floor.

It's all part of their very sophisticated research.

Also, they like belly rubs. Something I believe is true of all physicists.
posted by quin at 10:11 AM on December 29, 2008 [3 favorites]

Some satellites and spaceships do attitude control with rotating internal gyros. I wonder if any do it via the cat method of shifting moments of inertia around and rotating the body itself.

For example the Hubble Space Telescope uses momentum (reaction) wheels in order to do precise positioning and tracking of celestial objects...

No offense, but you just took N sentences to re-tell me what I myself just said in one sentence. My question is not "can satellites rotate using some method, perhaps with special equipment?" My question is "can satellites rotate using no other equipment than what they'd need anyway, plus some kind of rotating connector in the middle?" I.e. like a cat, which has no reaction wheel and instead just gyrates around to achieve the same effect without incurring any extra mass cost.
posted by DU at 10:33 AM on December 29, 2008

Hmmm... so, is there a cat-size limit on this? I demand experiments involving dropping fully-grown Siberian Tigers from three-story balconies.
posted by Tomorrowful at 10:50 AM on December 29, 2008

I once read a paper that showed tailless cats, like Manx house cats and Lynx, had better balance than cats without tails. They were unable to conclude if the tail was more to balance so that the work of tail management threw the tailed cats off-base enough to give the tailless cats an edge, or if the tailless cats worked harder on their balance because they did not have a tail to help them as a counter-balance in day-to-day balancing acts.

If I could remember who got the money for that study, we could get them on the Tomorrowful tiger project.
posted by Lesser Shrew at 11:11 AM on December 29, 2008 [1 favorite]

Cats aren't special in this, my ferrets can self-level in midair too.
posted by Evilspork at 11:18 AM on December 29, 2008

Ferrets are basically stretched kittens.
posted by Artw at 11:20 AM on December 29, 2008 [1 favorite]

They're a puppy/kitten/slinky hybrid.
posted by Evilspork at 11:27 AM on December 29, 2008 [2 favorites]

My cat is a gluttonous mass of fur and blubber. I'm not worried about my cat falling. I'm worried about him falling on me. Self-righting or not, he's still a dangerous projectile.
posted by grounded at 11:51 AM on December 29, 2008 [2 favorites]

"parachute safely into Borneo"

I was REALLY disappointed that wasn't a YouTube link. :(
posted by Jacqueline at 12:05 PM on December 29, 2008

No offense, but you just took N sentences to re-tell me what I myself just said in one sentence. My question is not "can satellites rotate using some method, perhaps with special equipment?" My question is "can satellites rotate using no other equipment than what they'd need anyway, plus some kind of rotating connector in the middle?" I.e. like a cat, which has no reaction wheel and instead just gyrates around to achieve the same effect without incurring any extra mass cost.

But you see, the satellite and the cat are exactly the same. They both have a rotating joint -- the cat's spine and the satellite's wheel axle. The cat's forebody is attached to one end of the joint and the hindquarters are attached to the other end of the joint. For the satellite, the motor's rotor is attached to one end of the joint and the stator and satellite are attached to the other. One rotates one way and the other rotates in the opposite, the same as the cat.

Another example would be the rotating solar panels on the space station which rotate to keep pointing at the sun. The momentum of the panel rotation is matched by the momentum of the station. The same is true for directional antennas.
posted by JackFlash at 12:35 PM on December 29, 2008

Evilspork : They're a puppy/kitten/slinky hybrid.

Yes. I see where you are going with this, I think. Add to that a bit of magpie (oh they love the shiny stuff), a maybe a little speedballing meth/ quaalude addiction issues, and a desire to hunt in packs while, at the same time, beating up everyone around them and I think you have the ferret mixture down.

Also, certain parts of my family.
posted by quin at 1:11 PM on December 29, 2008

Don't forget skunk.
posted by burnmp3s at 1:23 PM on December 29, 2008

Difficult to believe these are the same animals which will happily roll right off counter tops when petted or collide with literally everything while chasing collimated light... or stand in the middle of a plate of tuna fish.

They do that purposely. Mine will jump on my desk and start pushing things off it to attract my attention.
posted by mike3k at 2:35 PM on December 29, 2008

Rats. Search didn't turn up a Hello Kitty parachute. But a more technical approach does exist for dropcats....

(It turns out dropcats is a...well, I-hope-not-real word.)
posted by Kronos_to_Earth at 4:07 PM on December 29, 2008

(looks down chasm)

We're going to need a louder cat.
posted by Artw at 4:55 PM on December 29, 2008 [1 favorite]

Vitalic - Poney Part 1 Disclaimer: No ponies. Or cats for that matter.
posted by dhartung at 4:59 PM on December 29, 2008 [1 favorite]

Don't forget skunk.

Ferrets don't smell any worse than dogs, assuming you don't clean up after either of them. And cats smell worse, if you count my neighbor's incontinent feline.
posted by Evilspork at 5:21 PM on December 29, 2008

The cat's forebody is attached to one end of the joint and the hindquarters are attached to the other end of the joint. For the satellite, the motor's rotor is attached to one end of the joint and the stator and satellite are attached to the other.

I understand that the mechanics are the same. This is not my point. My point is that the mass allotment is not the same. The cat's forebody and hindquarters are useful even absent any rotation function. The gyro of a satellite attitude control system is not (well, except for the cases where it is....). That is to say, satellite designers have added the ability to do angular momentum style control by adding some specialized hardware. Cat designers can do angular momentum style control by hacking the hardware they already have.
posted by DU at 7:46 PM on December 29, 2008

Yeah, well cats can't fly through space. So there.
posted by ryanrs at 1:25 AM on December 30, 2008

DU, I think most spacecraft carry 4 to 6 momentum wheels for full 3-D pointing with redundancy. No way to do that by cutting up the satellite. Besides, protrusions like steerable solar arrays and antennas would cause wobble. Not to mention the nightmarish integration problems. How do you pass power through the moving joint? And thruster propellant? It would be completely unworkable.
posted by ryanrs at 1:49 AM on December 30, 2008

Well, the joints don't have to fully rotate, as demonstrated by the cat. Also, "completely unworkable" sounds to me like "insufficiently advanced engineering" again pointing to the existence of cats as my proof of concept. Not that I'm volunteering to try to build a catellite.
posted by DU at 4:55 AM on December 30, 2008

OK, lead weights in its feet?

Tht would explain how a ten pound cat can apply 57 pounds of pressure to the hurtiest part of your solar plexus when she stands on you.
posted by louche mustachio at 2:44 PM on December 30, 2008 [1 favorite]

I suspect you could do the cat-like reorientation trick (which doesn't require an internal gyro) if you had the ability to move mass closer to and further away from the satellite's axis of rotation.

The key to the cat maneuver is that it can stick two of its legs out, increasing the angular mass ("mass moment of inertia" if you prefer) of one portion of its body, pull two legs in, reducing the angular mass on another part, and then turn one portion 'against' the other portion.

A cat that wasn't free to stick its legs out wouldn't be able to do this twisting trick. It's essential to be able to increase the angular mass of one section relative to another section (with a pivot in between), and then reverse the situation in order to straighten back out.

If you wanted to design a satellite to take advantage of this, it would need to be able to change the angular mass of certain sections with respect to other sections, and then reverse the imbalance. In addition to doing it the way the cat does, by sticking relatively heavy limbs out and then pulling them back in, you might be able to do it by actually moving mass.

I.e., if you had tanks that could be filled with either high-density fluid (water) or low-density fluid (hydrogen), and the ability to pump them around, you could increase the angular mass of various sections by actually increasing the rest mass of that section, by moving fluid around. Then you'd rotate the "lighter" section using the "heavy" section as an anchor, overturning it slightly, then pump the fluids around to make the "light" section heavy and the "heavy" one light, and reverse the motion to bring the sections back into alignment with regard to each other. You'd have to be careful how you moved the fluids around (they'd need to flow through the axis, I expect), but unless I'm missing something obvious I think it would work.

It's just inelegant and far more complex than the flywheel arrangement used by most spacecraft. What cats do is a really, really impressive trick, given that they don't have internal flywheels (but have the requisite 'hardware' to alter their front-half and back-half's angular mass independently, just because it's also a convenient arrangement for walking around), but if you have the ability to create freely rotating shafts (which with certain rare exceptions don't exist in the animal kingdom), and don't care to have jointed legs and arms, the flywheel requires fewer moving parts.

This all leads me to wonder ... do experienced astronauts who have spent a lot of time in zero-G use methods like the cat's to turn around when unable to reach an anchor? If you were in free space and unable to use anything external, it's probably about the only reasonably-convenient way to turn yourself around to face a different direction.

I think the motions for a human would be something like this: (1) spread legs as far apart as possible while bringing arms to chest, (2) twist at waist and shoulders as far as possible, (3) bring legs together and straight, toes pointed; extend arms straight out at sides, (4) twist waist and abdomen to bring in line with shoulders, (5) repeat as necessary, since I suspect you'd only get a few degrees rotation out of each movement. I bet if you did it more than a few times and got into the rhythm of it, it could get pretty natural.
posted by Kadin2048 at 8:24 PM on December 30, 2008 [2 favorites]