All language subtitles for Mysterious Planet Series 1 Part 2 Giants of the Caribbean 1080p

DAVID SCHWIMMER: Our planet
still hides many mysteries.

In 2009, marine
biologists discover

something extraordinary--

whale sharks, more
than 400 of them

all in the same place
just off the coast

of Mexico, the largest
gathering of the world's

largest fish ever seen.

But why are they here?

The all-inclusive resorts?

To find out, we need
to travel back in time

to a lost civilization and
its sacred underworld, home

to monsters and
alien life forms,

to the clashing of continents,
and to the day when

a cosmic catastrophe completely
rewrites the story of life

on Earth.

Hi.

Don't mind the book.

I'm Detective David
Schwimmer, and it's

a crime you haven't watched this
episode of "Mysterious Planet--

Giants of the Caribbean."

Can someone get the book?

The largest fish
on Earth cruises

through the clear
waters of the Caribbean.

A whale shark, 25-feet
long, as big as a bus--

or twice the size of
a New York apartment.

Unlike other sharks known
for their killer instinct

and lethal jaws, this
one's taken a very

different evolutionary path.

It has teeth, around 3,000
of them, but they are tiny,

and it doesn't use
them to eat or to open

difficult bags of chips.

Its mouth, however, is huge--

over 5-feet wide.

The world's biggest
shark is a filter feeder.

Like a giant underwater vacuum
cleaner, it sucks in water

and filters out microscopic
plankton using spongy pads

hidden behind its gill slits.

It can filter two
Olympic-sized swimming

pools of water every day.

Just like me, whale sharks are
loners, constantly on the move,

wandering the tropical
oceans of the world.

Now something is calling
these solitary creatures

together to the
largest gathering

of their kind on Earth.

But the whale shark's story
doesn't start on Earth.

It starts one day 66 million
years ago in outer space.

Space sharks!

It's one of the worst days
in our planet's history

that wasn't my 11th birthday.

A piece of rock the
size of Manhattan

has a date with
destiny, a collision

course with planet earth.

The mega disaster that follows
changes life on Earth forever.

Millions of years later,
it helps create the world's

largest gathering
of whale sharks

in the very same
place where it lands,

Mexico's Yucatan Peninsula.

Just off the coast
of the Yucatan

is an underwater wonderland.

The sun, and clear,
shallow water,

create the perfect conditions
for some of the most

extensive coral reefs on Earth.

They home to over
500 species of fish

and a bounty of food
for hungry grazers.

Not a coincidence.

But further out beyond the
reef, the Caribbean Sea

is a blue desert.

The water is so clear
because it contains

almost no sediment or plankton.

And yet, hundreds of whale
sharks are heading this way--

and that guy.

Why are they traveling
thousands of miles

to reach a place where there
appears to be no food for them?

Also known as going
home for the holidays.

The search for answers begins
on land or, more precisely,

underneath it.

Beyond the coast,
the Yucatan Peninsula

is a wilderness of
lush rainforest,

flat and featureless like a
green carpet with no rivers

or streams anywhere in sight.

Yet a mysterious civilization
called the Maya thrived

here for a thousand years.

How did they survive with no
obvious source of fresh water?

The answer lies in these
strange, round pools.

There's another.

Known as cenotes, they
are the key to all life

on the Yucatan, the
only source of drinking

water for animals and humans.

The Maya built their
cities and temples

around these natural
reservoirs, and they held

great spiritual significance.

Cenotes were passages to the
underworld, the crossroads

between the living and
the dead, places of ritual

and human sacrifice.

OK, I didn't expect that part.

But they really are
portals to another realm

for those brave enough
to enter, like Derek.

Underneath the
forests of the Yucatan

is one of the wonders
of the natural world,

the largest underwater
cave system on Earth.

Divers recently
discovered that one

of the largest cenote systems
is over 200-miles long.

But to fully understand
the whale shark mystery,

we'll have to go even deeper.

Off Mexico's Yucatan
Peninsula, an incredible event

is about to happen,
the world's largest

gathering of whale sharks.

It's like Woodstock
for whale sharks.

Vital clues to this
biological mystery

are hidden nearby in a
maze of water-filled caves.

It's an alien realm down here
with unearthly landscapes,

giant caves decorated with
ornate stone sculptures

like otherworldly cathedrals.

How was this vast underwater
labyrinth created?

As divers venture deeper
into places that have never

been seen before, they
swim back in time, which

should be an Olympic event.

Fossilized coral
hidden in the stone

walls, proof that these rocks
were formed under the ocean.

But the spectacular
stalactites only form in air,

so what gives?

The only explanation for
these conflicting clues?

The Yucatan and its
unique cenote network

have undergone massive
changes over time.

It's this violent past
that holds the key

to our whale shark mystery.

We're like naturalist
Agatha Christies.

100 million years
ago, what is now

the Yucatan Peninsula was the
bottom of a warm, shallow sea.

Over millions of
years, coral reefs

build up a layer of limestone
almost a mile thick.

And as powerful tectonic forces
stir beneath the Caribbean,

they begin to push
this limestone slab up

above the water.

Rain then begins to dissolve
the exposed limestone

and gradually carves
out tunnels and caverns.

Stalactites begin to form like
melted candles, drip by drip,

over millennia.

In some places, the roofs
of these tunnels collapse,

creating the cenote entrances.

But then the Earth's climate
changes dramatically.

Water levels rise,
flooding the caves,

the final step in creating
the underwater labyrinth we

see today.

That's not scary.

But this violent
geological past has

a far wider impact,
over time, affecting

the whole of the Caribbean.

Venturing deeper into
the Mayan underworld,

more mysteries are revealed.

A ghostly boundary, like the
surface of a shimmering lake,

but underwater.

This is the halocline, no
relation to Kevin Kline,

where fresh water from
above meets sea water below.

And it's a vital clue in the
mystery of the whale shark

gathering, proving that the
fresh water cenote network is

actually connected
to the Caribbean Sea,

forming the largest underground
river system on our planet.

And this unusual river system
has an equally unusual effect.

On its slow journey
beneath the Yucatan,

all traces of silt and
particles settle out.

So by the time it
reaches the ocean,

the water is crystal clear.

That's why coral reefs can
thrive so close to shore.

They need clear
water to survive.

That makes sense.

But it's also why,
further out, the Caribbean

Sea is a blue desert, at
least most of the time.

It's winter, and something
amazing is about to happen.

The blue desert
is suddenly alive,

sardines feeding on a sudden
explosion of plankton.

Giant schools of
fish race to take

advantage of this
seasonal feast,

and predators are
close behind them.

The largest gathering of
whale sharks in the world

will soon happen right here in
the clear waters off Mexico.

It should be impossible
for these barren waters

to sustain such an event.

It's like the Fyre Festival.

But a sudden explosion
of life is a clue to why

this place is so special.

Bonito, a small species of
tuna, rise from the depths

and launch themselves on
the helpless sardines.

Tuna are the sports
cars of the fish world,

fast, sleek, and powerful.

They split the sardines
into small groups

and annihilate them.

For the confused sardines,
the only escape is up,

but the surface
holds another terror.

Frigatebirds join the feast
and attack from above.

Unlike most seabirds,
their feathers

aren't waterproof, so they
can't dive for their food.

Instead, they hover and pick
off sardines one by one.

It's like me eating
a Caesar salad.

But where did all this life
come from in what is supposed

to be a lifeless place?

Again, the answer lies in
this area's turbulent past.

20 million years ago, the same
forces of geological violence

that gave birth
to the Yucatan are

reshaping the whole Caribbean.

Continents collide
and islands shift,

creating a narrow channel
between the Yucatan

and the island of Cuba.

The waters of the
Caribbean start

to funnel through
this gap, creating

a powerful new current.

But most important is what
happens under the surface.

Deep down, the current
follows the seabed,

but as it hits the
corner of the Yucatan,

it's kicked upwards,
transporting nutrients from

the seabed towards the surface.

But the upwelling doesn't act
alone, upwellings rarely do.

Right now, it's the
strong winter winds

mixing surface waters that
are the final ingredient

for this explosion of life.

And the wanderers
of the open ocean

are quick to take advantage.

The sardines that have escaped
the bonito and the frigatebirds

continue to feed
on the upwelling,

but they're about to face the
ultimate Caribbean predator.

The sailfish, the fastest
animal in the ocean, unless I'm

being chased by a sailfish.

And it has company.

Their streamlined bodies
can cut through the water

at 30 feet per second, and
sailfish hunt as a pack.

While the pack
corrals the sardines,

the first hunter approaches,
but not at full speed.

Sailfish attack slowly
and deliberately.

It inserts its bill into
the bait ball almost gently,

then knocks a sardine out
of the safety of the school,

like an Olympic
fencer eating a kebab.

Then the next hunter
takes its turn.

Even if they don't
succeed at first,

their slashing bills
wound many sardines,

making it easier for the
next sailfish to catch one.

As they attack, the predators
flare their signature sail

and pectoral fins to stabilize
their body and strike

with better precision.

The sailfish attack
relentlessly until the bait

ball is wiped out, then
disappear back into the blue.

Yeah, that's not ominous at all.

Only a few sardines
survive, not a great day

for the old sardine.

This intense explosion of life
dies away as the winter winds

subside, and the nomads
of the open ocean

move on to search
for the next feast.

The waters off the Yucatan
are clear and empty once more.

But inland, deep below
ground in the cenote network,

other life and death
dramas are playing out.

The ancient Maya who once ruled
the Yucatan believed cenotes

were portals to the
land of the dead.

They called this realm Xibalba,
which means place of fright,

a dark and dangerous
underworld ruled by death gods

and bloodthirsty predators.

Today, we are discovering
the Maya were right.

There are strange and
frightening creatures living

in this underwater
labyrinth, and my guess is

they're pretty weird looking.

The world's largest
gathering of whale sharks

occurs off the coast of
Mexico, and its mysteries

are tied to secrets hidden
deep in an underground maze.

Only a few animals
can survive down here

in the darkness,
bizarre species uniquely

suited to life in
the underworld,

like the Mexican blind brotula.

This fish's ancestors found
their way into the cenotes

from the sea and never
found their way out.

Over time, they evolved
to become specialist

dwellers of the darkness.

There's no point in being
colorful in the pitch black,

so they lost all
pigment from their skin,

like me with my shirt off.

And it's useless having eyes,
so the cavefish lost those, too.

Now, these blind
predators sense vibrations

through their thin skin
and feel their way around

with two spindly
pelvic fins, creeping

across the cenote floor
searching for prey

like a tiny Mayan death god.

They're the apex
predator down here,

the equivalent of a great white,
but just four inches long.

Scientists are still
discovering what

lives in the dark labyrinth
beneath the Yucatan Peninsula.

It's estimated that just 10%
of the underground river system

has been explored.

Every dive seems to bring
incredible new discoveries.

In a handful of
cenotes are wonders

seen nowhere else on Earth.

Strange formations
hang from the walls

and ceiling of this chamber
like college dorm showers.

The stunned divers
who discovered

them called them Hell's
Bells, and the name has stuck.

The alternate name
was cavern churros.

The largest are over
six foot long, yum.

When scientists
analyzed them, they

realized something amazing--

Hell's Bells are alive.

Although they're mostly
made of limestone,

they are in fact colonies
of primitive bacteria.

They don't need the
sun to provide energy.

They don't even need oxygen.

Instead, they feed
directly on a hazy cloud

of toxic chemicals trapped
in these particular cenotes.

Some scientists believe this may
be what the first life on Earth

looked like billions
of years ago.

Or it could be a realistic
model of primitive life

on other planets.

At last, the dark
underwater labyrinth

gives way to the clear,
blue Caribbean Sea--

ah, that's better--
where the secrets

of the world's biggest
gathering of whale sharks

are finally coming to light.

It's summer in Mexico's
Yucatan Peninsula.

Tourist season is in
full swing, and visitors

from all around
the world are drawn

here, including giant fish.

Hundreds of whale sharks
from all over the Atlantic

are converging on the same
small patch of open ocean

about 20 miles offshore.

The biggest gathering of
the biggest fish on Earth

is about to begin,
and now we know why.

This time, it's the summer heat
that energizes and intensifies

the Yucatan's upwelling.

And once again,
nutrient-rich water

is being forced to the
surface of the Caribbean Sea,

causing life to explode.

Bonito tuna arrive
in vast numbers,

and whale sharks begin to suck
in water and filter it of food.

Aw, he looks happy.

First, dozens, then
hundreds, a spectacle

seen nowhere else on Earth.

But what exactly
are they feeding on?

There are other whale shark
gatherings around the world

where they feed on plankton
in murky coastal waters,

but the biggest
gathering of them

all is in the clear,
blue offshore waters

of the Caribbean.

Here, hundreds of the
biggest fish on Earth

are gorging on something
different, something

invisible to the naked eye.

And the key are the Bonito tuna.

They're not here to feed.

The warm summer currents
and the flush of nutrients

make it a perfect time
and place to spawn.

Every night, the huge
schools of spawning Bonito

produce billions of
tiny transparent eggs.

If you could see them,
they would fill the ocean.

They float to the
surface in a dense layer

of nutritious food
so concentrated

that the giant fish
don't even have to move.

They just hang there, consuming
over 300 pounds of eggs a day,

like an all you
can eat caviar bar.

This is the ultimate reason for
this extraordinary gathering,

a nutrient explosion
that triggers

a mass tuna spawning and a
feast for hungry whale sharks.

And it's all thanks to the
unique geological history

of this one small area
off the Yucatan Peninsula.

But there's one last
twist in the story

and a surprising connection
between the Yucatan,

whale sharks, and the
massive cosmic disaster that

helped wipe out the dinosaurs.

The Yucatan is
honeycombed with cenotes

and underground
passages, but they're

not just randomly scattered.

Plotted on a map, a
clear pattern emerges.

The deepest cenotes are part of
a huge ring 120-miles across,

the lingering footprint of
a gigantic crater and ground

zero for one of the
largest cosmic catastrophes

in Earth's history.

It always comes back to things
slamming into this planet.

Mexico's Yucatan peninsula is
the site of the world's biggest

gathering of whale sharks.

It is also the scene of one
of the largest disasters

to ever strike the earth.

And the two are connected.

It begins around 66
million years ago

when a meteor the size
of Manhattan takes

aim at planet Earth.

It tears through the atmosphere
at 20 times the speed

of a bullet and strikes a
shallow tropical sea, blasting

a crater 15-miles deep--

yikes-- and triggering
earthquakes,

volcanic eruptions,
and mega tsunamis.

Do we have ways to
prevent that now?

Worse is to follow.

The world burns, and the
debris from the impact

blots out the sun for years,
killing all plant life

and leading to the collapse
of global food chains.

Sound familiar?

50% of the species on
Earth become extinct.

Over the next 66 million
years, the crater

becomes buried under
almost a mile of sediment.

Today, the only visible
sign of it on the surface

is the ring of
cenotes which formed

around the edge of the
crater where the limestone

was most heavily fractured.

As devastating as this
mass extinction was,

it turns out the
whale shark may have

reasons to be grateful for it.

Before this extraterrestrial
disaster struck,

they didn't even exist.

The oceans were once home
to a whole different group

of giants.

Titanic filter feeders
called Pachycormus

rule the ancient seems.

Some are at least 54-feet long,
the largest fish to ever exist.

Think of the size of the bagel.

When the Pachycormus
ruled the seas,

the whale sharks ancestors
were small bottom dwellers,

like today's carpet sharks.

But their long reign
comes to a dramatic end.

When the meteor
strikes and the sky

goes black, marine food
chains collapse, too.

Without the sun,
the plankton dies,

and there is nothing for
giant filter feeders to eat.

The Pachycormus become extinct,
along with 90% of the species

in Earth's oceans.

But life always finds a way.

Eventually, the sun
breaks through again.

Marine plankton gradually
returns to the tropical oceans,

creating a rich food source
with nothing big to eat it.

The small, bottom-dwelling
carpet shark

survive the mass extinction
and take advantage

of this gap in the market.

One group evolves to
become giant filter feeders

and takes the title of
biggest fish on the planet.

Don't you want to just stick
your finger in his mouth?

Yeah, I wouldn't.

OK, yeah, that-- nope.

The giants of the Caribbean
ultimately owe their existence

to one of the worst
days in Earth's

history, so, silver lining.

And by a cosmic coincidence,
their biggest gathering

occurs almost exactly at ground
zero of this mega disaster.

After weeks, or even
months, of feasting,

the incredible gathering of
giant fish comes to an end.

Hundreds of whale
sharks begin to disperse

and head their separate ways.

But where do they go?

Considering how large and
conspicuous whale sharks are,

it's surprising how
little we know about them.

We know they swim thousands of
miles to get to the Yucatan,

but how do they navigate?

Nobody has ever seen the
giant fish mate or give birth.

Is there a secret whale shark
breeding ground or singles bar?

They can dive to over a
mile deep indefinitely,

so their secrets may
be hidden way below us.

The planet is still
full of mysteries.

I'm David Schwimmer, and this
has been "Mysterious Planet."

[music playing]

Seriously, where do
the whale sharks go?

Anybody?

Anybody?