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.
