So in this video, we're seeing the mantis shrimp
about to get really angry at a tiny shell.
Hi.
I'm Dianna.
You're watching "Physics Girl," and I'm
about to get curious again.
I'm here at Scripps Institution of Oceanography,
and I'm going to talk to my friend
Dr. Kate Furby about mantis shrimp.
They have to get really mad to eat.
DIANNA COWERN: Oh.
[LAUGHTER]
[INAUDIBLE] believe you.
Mantis shrimp are amazing creatures.
MAYA DEVRIES: All right, so you're
going to tickle it with this paint brush.
Mm-hm.
And it's going to-- it's probably going to smash it
and see if we can record it.
[QUICK SNAPPING]
Ooh!
That was a good one.
I think it struck with both of its--
MAYA DEVRIES: Wow.
Oh my gosh!
The moment that they hit lasts a fraction
of a millisecond, which is why this footage was captured
by scientist Maya Devries at 20,000
and 40,000 frames per second.
[LOW THUD]
There are hundreds of different species
of mantis shrimp.
DIANNA COWERN: Got it.
And they live all over the world.
It's kind of crazy how prolific they are.
And then they come in, like, all different sizes
and all different colors.
And these shrimp are smashers, so they
have what's called a raptorial appendage that's
this modified claw.
I first heard about mantis shrimp in a viral video
by Ze Frank, "True Facts."
And I don't know about you, but this animal just
keeps popping up.
So one thing finally convinced me to make a video about them,
and that was the force mystery.
In the early 2000s, biologist Sheila Patek
was studying the force of a mantis shrimp punch.
She found that they were capable of,
get this, 200 pounds of force.
Which is like setting a rock on your finger
and lightly jumping on it.
Yeah, I could probably break it.
But even more strange, she saw that there were
two spikes in the force graph.
One for the initial punch, probably.
And then something else was going on.
The mantis shrimp punch is fast, obviously.
But how fast?
NARRATOR 1: --unfurl as fast as a .22 caliber bullet.
NARRATOR 2: [INAUDIBLE] as strong as a .22 caliber bullet.
NARRATOR 3: --with the force of a .22 caliber bullet.
NARRATOR 4: --at the speed of a .22 caliber bullet.
But what does that mean?
The acceleration of the claw is similar to a .22 caliber
bullet.
Acceleration.
That's what's going on.
Come on guys.
NARRATOR 1: --unfurl as fast as a--
NARRATOR 2: --as strong as a--
KATE FURBY: --with the force of a--
NARRATOR 3: --the speed of a .22 caliber bullet.
Pull it together, you all.
The acceleration is like going from 0
to 60 in 0.2 milliseconds.
In fact, the claw gets up to 45 miles an hour.
Hit a shell with that speed, and you'll get one nice force peak.
Hit a shell with that speed in water and something else will
happen .
Looking back at Devries' footage,
there's one frame where something shows up.
Right there.
It's a bubble.
The crazy acceleration and force cause
cavitation, which is this.
The bounceback causes the club in the shell
to move apart so fast that they leave
behind a tiny area of very low pressure approaching a vacuum.
But when you drop the pressure real
low in water, what happens?
DIANNA COWERN: Water in the cup.
Vacuum pump is on.
Pressure is going down.
MAN: Oh.
You see it boiling.
Oh look, look look.
DIANNA COWERN: Is it boiling?
MAN: Yeah.
Yes.
It's boiling.
DIANNA COWERN: What?
Water is boiling.
When did it start boiling?
DIANNA COWERN: This water is still at room temperature.
But when you decrease the pressure, the water boils.
So you have low pressure.
And then the water boils.
And then you get a vapor bubble.
But it doesn't last very long.
Almost immediately, the bubble collapses.
And when it does--
[LOW THUD]
--energy and light are released in a violent process.
Violent enough to cause the second force
peak in that graph.
It's caused by cavitation.
And the temperature in that bubble
gets up to the temperature of the surface of the Sun.
Right.
The temperature inside of a tiny bubble as it
implodes next to a tiny shrimp.
Small and fierce.
So why are these animals so aggressive?
So the mantis shrimp are actually--
they eat a wide variety of things in the ocean.
But in that group of things that they eat, a lot of them
live in hard shells.
DIANNA COWERN: The fact that this smasher
type of mantis shrimp eats a wide variety of things,
including prey in hard shells and soft-bodied prey,
is actually a very new finding of Dr. Devries.
So the mantis shrimp is really good at smashing a shell open.
They're also quite territorial.
I think the more aggressive they are, the better,
the better footage they get.
DIANNA COWERN: Got it.
And so it's pretty funny trying to, like--
you're either trying to make the mantis shrimp, like,
feel hungry so it smashes the shell,
or you're trying to, like, make it annoyed.
Like, get out of my yard!
DIANNA COWERN: Yeah.
Can you do your best impression of a mantis shrimp?
[LAUGHS]
So I saw one time in my life.
I've been of coral reefs around the world for years,
and I've seen one.
So a mantis shrimp comes out like--
[LAUGHTER]
DIANNA COWERN: Seems pretty accurate.
Kate, you are a rock star.
Thank you so much to Dr. Kate Furby for helping out
with this video, and to Dr. Maya Devries.
And one more shout-out to "Deep Look."
They're an awesome channel on PBS Digital Studios.
If you haven't seen their video about mosquitoes,
it is terrifying and fascinating.
I've got a link to them in the description
at the end of this video.
They provided all of the footage of the colorful mantis shrimp
in this video, so a million thanks to them.
Thank you, guys, so much for watching me get curious again.
And happy physicsing.
[THEME MUSIC]