 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]
[LOW THUD]
[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]
