All language subtitles for Sharkcano 2020 WEB h264 CAFFEiNE_track3_eng

Narrator: Sharks and volcanoes.

Around the world,
where you find one...

Man: Oh, (bleep)!

Narrator:
...You find the other.

Narrator: This isn't
science fiction.

Man: Did we discover
a sharkcano?

Yeah, we did.

Narrator: We're following
world-renowned shark scientist

dr. Michael heithaus...

Mike heithaus: Keep the eyes
open down there.

Narrator: ...As he dives

into this strange
and dangerous realm...

Narrator: ...To uncover
the powerful attraction...

Narrator: ...Between two
fearsome forces of nature:

Volcanoes and sharks.

Narrator: An island
on the far side of the world,

home to one of earth's
most active volcanoes.

And some of the oceans'
most deadly sharks.

This is the french island
of la réunion,

a remote tropical paradise
in the indian ocean.

But here, paradise is
under siege by sharks.

Cécile lauret-stepler:
A surfer was attacked here.

He was killed, he was bitten.

But I don't know exactly what
happened, but yeah, he died.

He ended up dying.

Mike: More than other places
in the world

where you wouldn't even normally
think about shark attacks

when you go to the beach, in
réunion, it's been a real issue.

Narrator: Dr. Michael heithaus
is a marine ecologist

and a dean at florida
international university.

He's been studying sharks
for 25 years.

Mike: On réunion,
there's no question

the government's
taking this very seriously.

They've even instituted bans in
terms of getting into the water.

Narrator: Swimming has been
illegal on réunion since 2013.

It helps save lives, but
some brave the breakers anyway.

The numbers tell
the grisly tale.

Sharks have killed 11 people
here since 2011.

13 others lost limbs
but escaped with their lives.

That's 24 total shark attacks

on an island with fewer people
than san francisco.

So what's going on here?

Nobody knows for sure.

Local experts believe
that a perfect storm

of human and natural causes
are to blame.

Mike agrees.

But he also sees
something else.

A synergy between
réunion's sharks

and its churning,
active volcano.

Mike: When you look
at réunion island,

it's not an island
with a volcano.

It is a volcano that
has built an island.

Narrator: This bleak landscape
was laid in fire.

But it also reshapes the water.

Especially when it rains.

And in this tropical climate,
it rains a lot.

Mike: That is called erosion.

And when you don't have plants
to stabilize the soil,

you get sediment
flowing downstream

and ultimately into the ocean.

And that's a recipe
for turbid waters.

Narrator: So what does
murky, turbid water

have to do with réunion's
shark attacks?

Mike: In réunion, most of
the attacks have been attributed

to one species:

Bull sharks.

Narrator: Bull sharks
are distinguished

by their stout,
cigar-shaped bodies,

broad, rounded snouts
and small eyes.

They grow to about 7 feet long.

Mike: Yeah, bull sharks have
quite a reputation

for being aggressive.

They get really big.

They've got a mouth toward
the front of the head.

So they're built
for taking big prey.

Most sharks will
only attack prey

that's maybe 10%
of their own size.

Bull sharks will attack prey
that's almost their own size.

Fisherman: He's just shaking
the hell out of me.

Man: Holy (bleep).

Mike: When most people
think about sharks,

they think about white sharks.

You know, they've got those big
eyes, they've got good vision,

a lot of times we see them
in pretty clear water.

Bull sharks are
a little bit different.

That eye is a lot smaller,

which might mean that
they're less reliant on vision.

But what's beyond dispute

is that they have
an amazing sense of smell.

So even if the water
is really murky,

they should be able to find
and catch prey fairly easily,

and, in fact, may have
an advantage over prey

that don't have as good
a sensory system.

Some other species,
they like the clear water.

Bull sharks,
they're perfectly at home

where it's really, really murky.

♪ ♪

we're off the west coast
of réunion island,

and you can see the volcano
disappearing up into the clouds

with these really steep sides,
and you can see these ravines

that have been cut into
the side of the volcano.

So when it rains heavily you get
these huge torrents of water.

They come out the mouth
of rivers like this,

and it'll basically make the
ocean look like chocolate milk.

You know, the visibility
will go to basically zero.

Narrator: Mike wants to observe
the murky conditions

as a bull shark would:
Underwater.

But swimming here
is not only illegal,

it could also be lethal.

Mike: Since I'm not going to be
getting in the water myself,

we're going to have to use
the next best thing.

This is an underwater camera,

so think of a periscope,
only going the other way.

And what this will do
is let us get a view

of what's going on underwater,

see how good the visibility is,
what's down there,

and especially what
the water looks like

this close to
the mouth of a river.

♪ ♪

ugh, yuck.

I am seeing a whole lot
of greenish-blue gunk,

and you just see the light
is just picking up

all of that particulate matter,

so the visibility here
is not very good.

We're not seeing very far
into the distance.

We're only seeing

maybe three or four feet
away from the camera.

So those are the kind of waters
that bull sharks

can still hunt in,

but prey would have
a lot harder time getting away.

Narrator: About two thirds
of the shark attacks

here on réunion have occurred

in turbid water conditions
like these.

So just how well
can bull sharks hunt

in murky, turbid water?

That's what mike
wants to find out.

Since he can't do it
safely in réunion,

he heads to
the next best place:

Bimini island in the bahamas,
famous for its bull sharks.

Mike's staging an experiment

to compare how well bull sharks
can find food in clear water

versus turbid volcanic muck.

Mike: So, we're here in bimini

because it's got a really nice
population of bull sharks.

Hopefully we're going to be able
to entice a couple in

and we'll be able to see
how quickly they can home in

on potential food sources,

when they're almost blinded
from the turbidity.

That's gonna tell us
a lot about how these sharks

might be hunting
in other areas like réunion.

Narrator: He'll observe
bull sharks feeding

in two different conditions:

First in clear visibility, and
then in near-zero visibility.

Duncan brake: Hey, mike.

Mike: Hey. Ready?

Duncan: As ready
as I think I can be.

Narrator: Mike's teaming up
with duncan brake,

a veteran underwater cameraman

with years of experience
swimming with sharks.

It'll be duncan's job
to document

today's bull shark experiment.

Duncan: I've dove with sharks
all around the world.

And the species that
I'm probably the most wary of

when I'm in the water with
is definitely the bull shark.

They can be very unpredictable.

I've seen their temperament snap
in an instant.

Going from incredibly mellow,
chilled out,

to just absolute chaos
underwater.

Narrator: To raise the stakes
even further,

today's experiment requires
swimming with bull sharks

in near-blackout
volcanic conditions.

Mike: Obviously there's
no volcano here on bimini.

So, we're gonna
stir up the bottom

and try to create
zero visibility.

Narrator: Mike will use
a blower to churn up sediment

and simulate turbid conditions,

like those found
around réunion.

His job can be done safely
inside a steel shark cage.

But for this experiment,
duncan needs to capture

clear footage of
the animals' behavior.

That means outside the cage.

A safety diver
will watch his tail

and fight off any sharks
that come too close.

Duncan: I was thinking maybe
we'll just swap roles

and I'll go in the cage, and you
can dive with the bull sharks.

Mike: I'm good.

(duncan laughs)

duncan: I don't usually mind
diving with bull sharks.

But we're engineering
a situation

where the visibility
is going to suck,

and we're not going
to have a clue

what the sharks are going to do.

So, yeah, I definitely grabbed
the short straw jumping in.

Narrator: Once they
stir up the bottom,

he'll basically be
swimming blindfolded

with a bunch of bull sharks.

Mike: Yeah, I don't care
how many dives you've done.

If you're in zero visibility,

especially with bull sharks,
it's scary.

Narrator: First, the easy part:
Feed the sharks in clear water.

Narrator: The bull sharks
attack the food

the instant it hits the water.

♪ ♪

♪ ♪

♪ ♪

♪ ♪

narrator: In clear water,

the bull sharks grab the food
almost instantly.

But mike needs to see how well
they work in volcanic murk.

Narrator: Mike and duncan know

that once the blower
kicks up the sandy bottom,

there's no going back.

Narrator: Dr. Michael heithaus
and his partner,

cameraman duncan brake,

are swimming with a bunch
of hungry bull sharks...

Narrator: ...And now
they're doing it blindfolded.

Narrator: Mike and duncan are
simulating volcanic conditions

to see how well bull sharks
can locate food

in murky, turbid water.

It'll help answer mike's
big, burning question:

Why are sharks attracted
to volcanoes?

Narrator: An imaging sonar
allows mike to see,

even in zero visibility.

Narrator: The bull sharks feed

in volcanic,
zero-viz conditions

with absolutely no problem.

Narrator: Mike has
all the data he needs.

They can pack it in.

(laughter)

narrator:
Duncan's stingray scare

signals a good time
to get out of the water.

Duncan: Whoa.
Oh, man.

That really escalated quickly.

They were very calm
and collected.

But then, when
the visibility was reduced,

we completely lost
the upper hand.

And it was definitely
their game.

Sorry.

(laughs)

narrator: For mike,
it was a different ballgame.

The imaging sonar allowed him

to see the bull shark behavior
perfectly.

Mike: That was amazing.

What incredible animals.

And then to be able
to stir up the bottom

and use the sonar to see
how well they navigate

that turbid water,
absolutely amazing.

Narrator: Today's experiment
has convinced mike

more than ever that bull sharks
don't just tolerate

turbid, volcanic areas,
they thrive in them.

Mike: In fact, the sharks
may like those areas,

because it's like
turning the lights out

for a lot of their prey.

That's kind of perfect hunting
grounds for a bull shark.

Narrator: Bull sharks are
intelligent predators.

If active volcanoes help create
a perfect hunting ground

for them, it's easy to see
why they hang out there.

But mike suspects there
are even more reasons

sharks are drawn to volcanoes,
both active and dormant.

To see if he's right,

he's heading back
to the indian ocean

100 miles east of la réunion...

...To the volcanic island
of mauritius.

Mike: Mauritius is about
8 million years old,

the volcano is dormant.

So what it really lets you do
is kind of control conditions

for active volcano,
dormant volcano.

And mauritius
may give us a window

into what réunion
might look like

several million years
in the future.

Narrator: Unlike réunion,

mauritius's dormant volcano is
covered in thick vegetation.

Mike wants to see if
the marine environment

looks any different,

and how that impacts sharks
and their behavior.

Once again, his underwater
cameraman duncan brake

is along for the ride.

Duncan: So, yeah,
we got out here

and it's looking
a little bit sporty to me.

Pretty big seas after
that storm rolled through.

Mike: Yeah! Yeah, and I've heard
it's not the swells

on the surface that we need
to be really careful of,

it's the currents underwater.

Duncan: What sharks are
we expecting to see

in this volcanic topography?

Mike: Well, out here,
probably grey reef sharks

are the most likely,

you know, they love being close
to these drop-offs.

Narrator: Grey reef sharks
are common

in this part of the world.

They grow up to 6 feet long,

and spend most of their lives
around coastal areas and reefs.

Mike: Sometimes grey reef sharks
can have a bit of an attitude.

So you really want
to watch their behavior.

They will put their pectoral
fins down and arch their back

and swim in
a fairly exaggerated way

if they want you
to get out of their space.

♪ ♪

♪ ♪

keep the eyes open down there.

Sharks, swell,
see how this goes.

♪ ♪

♪ ♪

narrator: An undersea paradise.

Jagged volcanic terrain offers
plenty of nooks and crannies

for corals to take hold

and for fish to hide
from predators.

Narrator: The shark food is
here, but where are the sharks?

Volcanic islands like mauritius
have a shallow coastal ledge

with a sheer drop-off
down to the ocean floor.

This is where reef sharks
can typically be found.

But here, there's no sign,

and no protection from
the open ocean currents.

(groaning)

♪ ♪

♪ ♪

narrator: These exposed
conditions are dangerous.

But a volcanic formation
looks to offer shelter.

Narrator: In here,
mike and duncan

are safely out of the surge,

but they're not out of trouble.

Narrator: Off the coast
of mauritius,

dr. Michael heithaus and
cinematographer duncan brake

scramble to escape dangerous
surge and ripping currents.

(muffled scream)

a narrow volcanic passage
offers shelter...

And company.

Narrator: Today is
their lucky day.

Narrator: They've been
searching for sharks

all morning.

Mike wants to see
how sharks benefit

from dormant volcanic islands,
like mauritius.

They follow the shark and
hope it leads them to more.

Narrator: Mike and duncan enter
a large volcanic cavern

with crystal clear water.

Narrator: They keep
their distance

and a sharp eye on the sharks.

Narrator: Mike is satisfied.

This healthy congregation of
reef sharks is proof positive

that even dormant volcanoes
have plenty to offer to sharks.

♪ ♪

♪ ♪

mike: Ah! That was fantastic.

Clear water,
great volcanic island

and lots of sharks.

Woo!

Volcanic islands are these
oases in the desert

where you've got food chains
that are just thriving,

and that's going to attract
animals from all over,

because it may be hundreds
or thousands of miles

to the next closest land.

Narrator: The lush reefs of
these remote volcanic islands

are a critical food source
for sharks.

And not just
the coastal species

that spend their entire lives
there, like reef sharks,

but also for big, roaming,
open-water monsters,

like the great white.

One such island is guadalupe,

a volcanic palisade
in the pacific,

150 miles west of baja, mexico.

In 2010, cinematographer
andy casagrande

was at guadalupe on assignment,

looking to film
great white sharks.

He got a chilling,
up-close-and-personal reminder

of how important these
volcanic islands are

to big pelagic sharks.

Andy casagrande: The holy grail
as a natural history cameraman

would be to capture great white
sharks breeding, mating.

But the next best thing
is feeding.

Narrator: Guadalupe's
rugged shores

are an annual birthing ground

to many types of seals
and sea lions,

like the enormous
elephant seal.

Andy: Elephant seals can dive
to like 8,000 feet,

hold their breath for 2 hours,
and they're very intelligent.

So, they're prey species

that's not easy for
a white shark to take down,

but very lucrative if they do.

Narrator: Elephant seals
haul themselves out

onto guadalupe's rocky beaches
twice a year,

to molt and mate.

Volcanic islands have
steep underwater flanks,

allowing white sharks to come
right up to the beach.

Mike: When they get in
close to shore,

those white sharks know
that they're going to be there.

And there's this narrow zone

where those seals have to get
on and off islands,

where they're really at risk.

It's a very narrow window
each year,

but it's a pretty important one.

Narrator: Andy is lucky enough
to be there

at exactly the right time.

The sharks are lurking.

And the seals
heading back to sea.

But andy's not seeing
any action.

Andy: We're trying to capture
these predation events.

We're striking out.
We're not seeing anything.

Narrator: Then he notices
a young elephant seal

making a break for deep water

and heading straight towards
the white sharks.

Andy grabs his camera,

but in that split second,
loses sight of the seal.

Andy: And then we capture
these birds on the horizon.

Man: Here he comes.

Andy: And we see they're
picking up bits of flesh.

We rush out there.

Really, there's lots of
sea gulls and the splashing,

and just, you know,
when I'm filming these events,

I almost get
an out-of-body experience.

Narrator: Andy plunges
his camera over the side.

He'll never forget
what he sees next.

Andy: It is ferocious.

And the blood and the bubbles.

It literally is something
out of a horror film.

Andy: It is ferocious.

It literally is something
out of a horror film.

Narrator: In the pacific,

off the remote volcanic island
of guadalupe,

cinematographer andy casagrande
gets a close encounter

with raw nature.

A great white shark
devouring an elephant seal.

Andy: There's a large elephant
seal with its head missing.

The shark grabbed the carcass,
thrashed it,

swam right up to us,

and basically, you know,
gave us this,

"hey, come on in,
the water's fine.

But I'm going to eat you
along with this seal."

narrator: Andy opts
to stay out of the water.

But big pelagic sharks
like the great white

seem to understand
that big, juicy meals,

like elephant seals,

can be scored around these
remote volcanic outposts.

So the question is, if volcanic
islands like guadalupe

are so tiny and isolated,
how do sharks find them?

Dr. Michael heithaus
believes the answer lies

with the shark's
mysterious sixth sense.

Mike: If you think about the
senses we have, we've got taste,

we've got touch,
we've got sight,

we've got smell,
we've got hearing.

Sharks have all of those.

And then they have a sense
that we don't have.

They can detect electric fields,

and all living things give off
those electric fields.

Narrator: This extra sense is
thanks to a secret weapon:

The ampullae of lorenzini,

an array of pores
spread across their snout

which picks up tiny changes
in electric energy.

Mike: So this electrical sense
that the sharks have

is incredible,
it's almost like a super power.

Narrator: Sharks use their
ampullae of lorenzini to hunt.

But scientists suspect sharks
might use this same super sense

to navigate open ocean

and track down bountiful,
remote volcanic islands.

Now mike is going
to put it to the test.

He's teaming up with
dr. Stephen kajiura,

a biologist and professor
at florida atlantic university.

Steve's been studying
the electrosensory capabilities

of sharks for years.

Stephen kajiura: All sharks
have the ability to detect

electric fields
in the environment

with their
ampullae of lorenzini,

their electroreceptors.

And that's well-documented.
They use that to find prey.

But it's interesting that
electricity and magnetism

are closely intertwined.

Narrator: If sharks
can detect magnetism

with their electrosensing
superpower,

then they might also
use it as a compass.

Mike: How?

It's probably got to do
with being able to detect

weak magnetic fields, you know,
the magnetic field of the earth.

But then if we think about
volcanoes and that lava,

it's got lots of iron,
which is naturally magnetic.

And so these lava flows
in volcanic islands

could serve as waypoints for
the sharks' sensory systems.

Narrator: But this theory all
depends on one big question:

Can sharks detect magnetism?

♪ ♪

♪ ♪

mike: We're targeting
hammerheads here,

and the reason for that

is that they've got lots
of ampullae of lorenzini

so they should be fairly
receptive to magnetic fields.

Of course, it doesn't hurt
that they're also super cool.

Narrator: Hammerhead sharks
are one of the ocean's

most distinctive predators.

Their broad head,
called a cephalofoil,

acts like an airplane wing

and offers incredible
maneuverability.

Large, powerful animals.

If provoked,
they can get aggressive.

♪ ♪

stephen: Here we have
a big 50-pound magnet.

This thing will lift an entire
50-pound steel block.

Mike: Yeah, those are strong.

I can't even come close
to pulling them apart.

Narrator:
Mike and steve's experiment

will use three magnets

to see if they trigger
a reaction from the sharks.

Stephen: So, what we have here
is not only the magnets,

but we also have
the control treatments.

These are just aluminum blocks,
also painted red.

They look identical, and so
the shark won't be able to tell

by looking at them what's what,

but one's putting out
a giant magnetic field

and one is, one is clearly not.

Mike: Okay.

So, we've got the control blocks
and the experiment blocks.

They're the same size,
they're the same shape,

they're the same color.

The only thing they differ in is
one is magnetic and one is not.

Narrator: If steve's prediction
is right,

the sharks will ignore the
non-magnetic aluminum controls

and react to the magnets.

Duncan: Now, are you
expecting the sharks,

are they gonna be
going at the magnets

or are they gonna be,
like, bounced off them?

What are you thinking
you're gonna see down there?

Stephen: I don't know.
It's hard to say.

It could go either way.

They could either be attracted
to them, they could be repelled,

they could just
ignore them completely.

Duncan: Alright, let's get
suited up, get down there.

Mike: Put these in action.

♪ ♪

♪ ♪

narrator:
It's an open-water laboratory.

The magnets in an arc
to the right,

and the non-magnetic aluminum
controls to the left.

Bait lures sharks
over the test field.

Narrator: A slew of
nurse sharks show up

with the hammerheads;
a welcome bonus.

Narrator: Now mike and steve
can look at how both species

react to the controls
and magnetic blocks.

Narrator: In bimini, bahamas,

a team of experts are hoping

to entice a couple sharks
for an experiment...

♪ ♪

...And get more than
they bargained for.

♪ ♪

♪ ♪

narrator:
They're testing if sharks

can detect magnetic fields.

The answer could unlock
a major mystery

about how sharks find

far-flung, food-rich
volcanic islands,

and whether the islands'
naturally magnetic lava rock

is involved.

For this open-water experiment,

they arrange three powerful
magnets to the right,

and three non-magnetic controls
to the left.

Narrator: A big hammerhead
glides over

the aluminum control
without a glance

and heads for the magnets.

Narrator: Hammerheads
ignore the aluminum,

clustering around the magnets.

The nurse sharks have
a greater response.

Narrator: Nurse sharks are
drawn to the magnets.

♪ ♪

♪ ♪

♪ ♪

♪ ♪

♪ ♪

♪ ♪

narrator: The sharks
are agitated,

possibly by the magnets.

♪ ♪

♪ ♪

stephen: That was fantastic.

That was great.

So many hammerheads down there,
all over the place.

Bunch of nurse sharks.

Nurse sharks were
biting at the magnets.

Really neat dive all-round.

Mike: So that dive was crazy.

We had nine hammerheads there,

seemed like countless
nurse sharks.

What we saw was that
both the nurse sharks

and the hammerheads
did respond to the magnets.

So, what we can
take away from that

is that those
weak magnetic fields

that are locked in volcanic rock

are something that
the sharks could detect

and may be able to use
in navigation.

♪ ♪

what scientists
are starting to think

is that they're probably using
the earth's magnetic field

to move around.

Now, when they get closer
to volcanic islands,

they might be able to use
that magnetic sense

to detect anomalies in the lava
that formed when it cooled.

Narrator: Evidence suggests
sharks use volcanic formations

to navigate, and volcanic
islands as food pit stops

in the wide-open ocean.

But what about
the volcanoes themselves?

Are sharks attracted to
the actual churning heart

of these fiery furnaces?

♪ ♪

dr. Brennan phillips found
the answer to that question,

almost by accident.

It's a case of truth
being stranger than fiction.

Brennan phillips:
Did we discover a sharkcano?

Yeah, we did.

Man: Oh, (bleep)!

(scream)

man: Holy (bleep).

Man: I'd be careful.
Oh, (bleep)!

Man: Holy (bleep).

Brennan: What makes working
around a volcano dangerous

is, well, it can erupt.

♪ ♪

so nothing over here
just to show anything.

Narrator: National geographic
grantee dr. Brennan phillips

studies underwater volcanoes.

He recently made
an astounding discovery

that could blow the lid off of
everything we know about sharks

and their attraction
to volcanoes.

Brennan: My expedition to
kavachi was about exploring

that volcano for
the first time really

using real scientific equipment.

Narrator: Kavachi,
an active underwater volcano

in the south pacific.

Its caldera, only 60 feet
beneath the surface.

Brennan was there
to analyze the volcano...

♪ ♪

...Not sea life.

Brennan: Kavachi is one of the
most active submarine volcanoes

in the world,
it can erupt at any time.

So probably the worst
possible-case scenario

is that hot magma could land
right into your boat

and it could burn a hole right
through the hull of your boat

or even through you.

Narrator: Brennan's team
launched a robotic camera

to get an up-close look.

Brennan: So it's a surface robot
that they could drive

using a little remote control.

It had the camera on it
and a few other sensors.

And the whole idea was
it could be lost if it need be.

And we drove that
right up into the volcano

as close as we possibly could

and waited, hoping that
a big eruption would happen.

And we got it.

Man: Kind of getting--
oh, (bleep)!

Man: Oh, yeah!

Man: Holy (bleep).

Brennan: That eruption
really caught us off guard.

It was very loud.
It was very violent.

It's certainly shocking.

And everybody kind of
snapped to and paid attention,

right when that went.

Man: Those guys
gotta be careful.

Narrator: But brennan
wasn't finished.

He wanted an even closer look.

Brennan: We actually wanted
to get images

inside of the volcano, inside
the crater of the volcano.

And so we used a
national geographic drop camera,

which is an autonomous
self-powered robot camera

that you can essentially
chuck off the side of a boat,

it will sink,
and for a set amount of time

that you program it for,
it will record video.

Men: Three, two, one.

Narrator: The drop camera sank

straight into the roiling heart
of the volcano.

Brennan: So we're
watching the video,

and all we're seeing is a lot
of cloudy water, orange water,

that we had come to expect
inside that plume.

And then out of nowhere
we saw a whole bunch of sharks

come right up to the camera,

and they're moving
very, very quickly,

and darting back and forth.

When we saw that,
we were, we were super shocked.

Man: Oh, nice. Look at that.

Narrator: Brennan captured
something never seen before:

Live images of sharks swimming

inside the caldera
of an active volcano.

Brennan: There's a lot of things
going against them

going into that volcano,

between the heat and the caustic
nature of all the water

that's coming out
of the volcano.

Those are all bad things for
fish and sharks to live in.

But these sharks seem to be fine
and thriving in there.

My thought is that they do leave
when there's an eruption,

that they can sense it and
they get right out of the way.

This seems to be a community
that is used to this activity.

Men: Whoa! Woo!

Mike: Dr. Phillips
brought back evidence

that sharks were
using this caldera.

And, you know,
why are they there?

One reason might be
there's some food,

another might be
it's nice, warm water.

Sharks will move
from warm to cold water

to get energy to feed,
maybe digest optimally,

or even speed up reproduction.

Who doesn't like a hot tub?

Brennan: Did we discover
a sharkcano?

Yeah, we did.

We found sharks
living in a volcano.

I think it's highly likely
that there are sharks

living in other
submarine volcanoes.

Narrator: We may not know
exactly why sharks are there,

but the incredible fact that
sharks are inside a volcano

shows these two
fearsome forces of nature

share a powerful connection.

Mike: Hey, sharks
like volcanoes.

And if you think about it,

volcanoes are just really
critical to ocean ecosystems.

I mean, they're these oases
out in the middle of nowhere.

Without them, it would
just be more open water.

There's no question,

we're really only scratching the
surface of what we need to know

about how volcanoes
affect sharks

and all the other species
that call these waters home.

♪ ♪

captioned by
side door media services