The Fastest Animals Are Way Faster Than You Think
Dianna: Hey… recording!
Joe: Yeah
Dianna: You did it!
This is my friend Dianna. You probably know her from Physics Girl.
Dianna: How's it going?
Joe: I needed to show you something because I'm not a physicist, I don't know physics
like you do.
Dianna: Ok, that's what I'm here for
I'm about to show her one of the fastest animals in nature.
You might be picturing something like this. Or this… or even this. But you'd be wrong.
The actual fastest animals on Earth can accelerate from 0 to 200 miles per hour five thousand
times faster than the blink of an eye. They can pull enough g's to turn your body into
jello. And they could hang out on your fingertip.
Dianna: Whoooooaah… (laughing) oh my gosh what is it even doing? Oh my gosh, you silly
bug!
These tiny animals can store and release energy in some mind-blowing ways, even better than
some of our most advanced inventions. And today, using some super-slow-motion macro
video, and a little physics, we're going to answer this question: How fast ARE the
fastest animals, and how do they do it?
[OPEN]
Hey smart people, Joe here. So humans have reached some pretty impressive speeds.
Of course, there are different ways to go fast. One option is you can speed up very
slowly, for a long time, like NASA's Dawn spacecraft. Its ion thrusters put out less
force than it takes to push a single key on a keyboard, but it accelerated to over 11
km per second by firing that tiny engine for nearly six years.
But the real challenge is getting going fast, quickly.
And that's where teeny-tiny bugs leave humans in the dust - along with pretty much every
other large animal on Earth. This awesome footage was captured by Adrian
Smith… …a biologist who developed a bit of an obsession
with studying nature's tiny speed freaks. And thanks to his YouTube channel…
…so have I. But before we go any farther, let's get back to our friend Dianna, so
she can explain the unique physics problem that these insects have solved:
So we're talking about little bugs, jumpin' fast. Velocity is just, like, how fast you're
going, in what direction. Acceleration is changing your speed or the direction that
you're going, and that's where you've gotta put in effort. I have to put in some
energy to change my velocity. Now imagine you wanted to change the speed
really fast. Thing is, things just want to stay going the
way they're going, and the same speed, or they want to stay not moving if they're
not moving. Things resist changes in motion. They have inertia.
And as you may know… Inertia is a property of matter
The last piece of analyzing a change in speed is to think about mass. And to think about
if I want to push something up to speed, like pushing a real big human up to a certain speed
takes a lot of effort, but pushing a small little human up to speed, doesn't take nearly
as much effort. And pushing a tiny, tiny little being up to
speed, I would just have to flick it!
So… you wanna flick tiny, tiny beings up to speed?
For science? Don't flick tiny, tiny little beings.
So there's an equation that describes the relationship Dianna's talking about: the
equation for kinetic energy. Energy is on the left, and on the right side we have an
“m” in there for mass. Which means that if we have a bigger mass, then the energy
we have to put in to move increases at the same rate. It's a linear relationship. And
that means if we have a smaller mass, then it takes less energy to move.
And having a tiny, tiny mass is what lets those bugs that we saw accelerate faster than
just about any other animals on Earth. But studying how they do that isn't easy, because
first, you gotta catch ‘em… or Adrian does, anyway.
So recently I was surprised when a bunch of really cool bugs showed up right outside my
door. These are springtails on the lid of my trash can. Springtails are tiny soil arthropods
that launch themselves into the air to avoid predators, or in this case my finger.
Springtail jumping hasn't been studied much so I collected those and brought them back
here to the lab, to film them with this high-speed camera. Filming them is a challenge, these
springtails are tiny, so the best way to handle them is to push them around with a tiny paintbrush.
Then the challenge is to follow them around with the camera, and hope they jump while
you've got them both in frame and in focus.
When I did manage to catch some on film, what I saw was astounding.
These springtails go really fast, really quickly, clocking an upwards acceleration of 700 meters
per second squared… in a fraction of a second. which is almost 20 times the acceleration of a top
fuel dragster, and about a hundred times quicker than an accelerating cheetah. “Fastest animal
on Earth”? I don't think so, kitty.
To do what these bugs do, even with their tiny mass, they have to store and release
a ton of energy all at once. Enough energy to send a springtail spinning at 374 flips
per second–almost 40 times faster than a spinning helicopter rotor.
But when scientists crunched the numbers, they were confused, because muscles alone
are physically incapable of producing that much energy in such a short amount of time.
It's the limitations of biology. Muscle tissue can only contract so fast, which means
it can only provide a finite amount of energy to accelerate. That's why humans can't
throw a thousand-mile-per-hour fastball. These bugs must be releasing that energy using something
other than muscle power alone. The answer? It's right in the name: They
use springs.
So what is a spring? A spring is a mechanical device that stores energy to be released later,
usually very quickly. The idea of springs is that you usually put in energy over a longer
amount of time, like you incrementally compress it, or stretch it, and then it snaps back
really fast.
The conventional spring is like the wound, tight coil of wire. Get down to the microscopic
level and you've got bonds between all these atoms and molecules, and you're stretching
those apart. So when you release the spring those atoms and molecules all snap back into
place. And you get this release of energy. And typically you push or you pull something
really fast.
So actually a spring is often made of little mini-springs, like all the atoms and molecules
act like springs themselves.
So the main idea with a spring is you can slowly store energy using a small amount of
force over a longer time, and then release that energy very quickly to do a lot of work.
Only instead of atoms in a metal being stretched like in a traditional spring, insects and
other super-fast creatures with exoskeletons, like the mantis shrimp, store and release
energy using their exoskeletons, which are made of flexible and stiff materials mixed
together. That's called a “composite” material, and engineers use them all the time.
A springtail's launching appendage is part of its exoskeleton, and it stores energy just
like the spring on a mousetrap. It stays locked and loaded, until … [mouse trap demo].
What's crazy is springtails aren't even close to the bug acceleration record.
These are froghoppers, little insects you might find sucking juices out of plants…
and in addition to looking very weird and cool, they're among the fastest jumping
insects ever recorded. The fastest froghoppers can accelerate at 5400 m/s2, just under 550
g's.
Froghoppers, and their cousins planthoppers and leafhoppers, do this using an incredibly
cool simple machine. They draw up their hind jumping legs, lock them in place with an actual
latch that sticks out of their belly, flex a big muscle to bend their exoskeleton, and
then open that latch to release the energy all at once. It's almost the same way a
crossbow, or catapult works, only here, they're using their flexible but strong exoskeleton
as the spring. I'm not an engineer, but the fact that they have simple machines: latches,
levers, and springs, built into their bodies, blows me away.
But… they aren't the fastest either. These are trap-jaw ants, and although they don't
move their whole bodies, they can snap their jaws shut in less than a thousandth of a second,
which is an acceleration of around 100,000 g's… that's more than the acceleration
of a bullet leaving a gun. And they do it by using their entire head as a spring.
So even though these ants are accelerating their jaws really quickly, the force they're
generating on impact is tiny relative to us. That's because their jaws don't have that
much mass. Basically, when this ant snaps against the tip of my finger, I can barely
feel it.
But organisms like these ants have evolved to meet challenges on their own physical scale.
The jaws of this ant have evolved ultra-fast acceleration to catch prey. And the forces
they generate might not seem like much to us, but to the ant it's enough for them
to do incredible things. Like this one, using its jaw snap to escape from the pit of an
antlion.
By timing those snaps perfectly, trap-jaw ants can catapult themselves more than 40
centimeters away. That'd be like me flinging myself back more than 100 feet.
That ant was the animal acceleration record-holder until 2018, when it was dethroned by the snap-jaw,
or dracula ant, which snaps its jaws in 23 microseconds. That's millionths of a second.
Twenty times faster than the trap jaw ant. Those mandibles go from 0 to 200 miles per
hour in point zero-zero-zero-zero-one-five seconds.
And it's hard to believe but the snap jaw was recently knocked out of first place by
a termite that can snap its jaw three times faster. And if you're thinking this video
looks a little unimpressive, that's because when you're filming at a ridiculous 460,000
frames per second, 128 x 128 pixels is the best that modern technology can offer.
What makes these tiny animals so impressive is that they've developed simple machines–latches
and springs–thanks to nothing more than the power of evolution. And these latches
and springs are the key to their record setting speeds.
If you've ever played paper football, you know it's a lot easier to launch by flicking
versus just swinging your finger. That's because you're using your fingers like a
spring and latch, storing energy in your tendons and muscles and releasing it quickly, much
faster than your muscles can move your finger alone. And when you snap? You're doing what
snap-jaw ants do when they push and slide their jaws past one another. But you do all
these things way slower than the bugs do, because you're a whole lot bigger and more
massive.
How much acceleration can humans handle? In 1954, to test what pilots could endure after
ejecting at high speeds, Air Force physician John Stapp shot to 623 miles per hour in five
seconds on a rocket sled, and slammed to a stop just one second later. He experienced
a record-breaking 46.2 g's, and for an instant, his 168-pound body weighed over 7,700 pounds.
But remember that a froghopper can accelerate at 550 g's, and the mandibles of the snap
jaw ants pull over 100,000 g's… that's insane.
They're able to do that because they're small. We are both subject to the same laws
of physics, us large mammals and those tiny bugs. But those laws sometimes apply to us
very differently: How we move through water, how hard or soft we fall, and how fast machines
can carry us. It's a good reminder that nature has figured out how to do things that
we can still only dream of.
Stay curious.
