All language subtitles for Planet.Earth.III.S01E02.Ocean.2160p.UHD.Blu-ray.Remux.HDR.HEVC.TrueHD.7.1.Atmos-CiNEPHiLES_ENG_Subtitles02

Much of our planet

still remains unexplored...

...for most of it
is covered by water.

Every journey below the surface

can reveal something extraordinary.

More than 1,000 new species are
discovered here every year.

The ocean is home
to 80% of all animal life

on Planet Earth.

But today,

thriving in this varied world

sometimes demands
the most surprising behaviour.

The shallow seas of the tropics.

This may look like a paradise...

...but beneath the surface,

it is an arena

for constant life-and-death struggles,

where not everything
is quite as it seems.

A predatory lionfish...

...on the hunt for shrimp
and small fish.

With so many places
for its prey to hide,

the lionfish has to be patient.

This shrimp appears tempting.

As the lionfish closes in,

it fans out its fins

to disorientate its prey.

The hunter becomes the hunted...

...tricked by one of
the shallow sea's

most extraordinary predators...

...a clown frogfish.

On its head, it carries a fishing rod,

a modified dorsal fin

baited with a lure,
easily mistaken for a shrimp.

But when the fish stop biting,

it's time to pack the rod away

and move on.

And for a frogfish, that takes time.

Rather than swim,

frogfish walk.

Its fins have, in effect, become feet.

It may not look pretty,
but what appears to be coral

living on its skin
is actually camouflage.

As every good angler knows,

picking the right spot is important.

Jigging the rod sends out
pressure waves

to attract the attention
of possible prey.

These dragonets are
certainly interested.

Almost there.

Hook, line and sinker.

Like all shallow seas,

the cold waters
off the coast of North America

benefit from the intensity
of the sunshine.

Here, that fuels one of
the fastest-growing organisms

on the planet...

...giant kelp.

Towering forests can eventually reach

the height of a 12-storey building.

These forests are nurseries
for young horn sharks.

As the sun begins to set,

they leave their daytime shelter

and set off into
the heart of the kelp forest

to find food.

Barely half a metre long,

this little shark
is extremely vulnerable.

There are monsters here.

A giant sea bass
weighing over 200 kilograms...

...and wolf eels with big teeth

that can crush little red sea urchins.

But the biggest danger comes
from other sharks...

...houndsharks...

...and huge
broadnose sevengills.

In this forest,

it pays to keep a low profile.

An angel shark...

...one of
the most deadly sharks

in the kelp forest,

and certainly the best camouflaged.

An angel shark
will lie in wait for days...

...but this one
has already attracted

too much attention.

It's not welcome here.

Now the coast is clear.

But angel sharks hunt
around the clock.

Openings for breathing
called spiracles

blow out sand
that helps cover its body.

The trap is set.

Staying close to the seabed

is a good way to avoid most predators.

Faster than the blink of an eye.

But it's not over yet.

Horn sharks have a secret weapon.

Sharp spikes keep them

very much off the menu for most.

So this young horn shark...

...can hunt in safety...

...for now.

Violent winter storms
batter these kelp forests.

The plants can be ripped
from the seafloor...

...and carried away
far out to sea.

The open ocean
is a vast, featureless desert.

Even a small piece of drifting kelp

can become valuable.

It's just what these fish have
been searching for.

Here, shelter, where eggs
can be laid unobtrusively,

is rare...

...so they make the most of it.

Each female produces up to 1,000 eggs,

and the males rush in
to fertilise them.

All this activity attracts
the attention of blue sharks.

They can travel thousands
of miles through the ocean

in search of food.

And they may not have eaten for weeks.

It seems that they're in luck.

But these fish are no easy meal.

They are flying fish.

The blue shark, however,

are not here for the fish.

They have come for the caviar.

But flying fish lay so many eggs

that the sharks' feasts
hardly make an impact.

And in a few months' time,

a new generation
will take to the skies.

Floating islands of weed

are always attractive to creatures

looking for shelter
out in the big blue.

But in today's ocean

they're being replaced
by something else.

Plastic.

12 million tonnes of it end up
in the ocean every year.

The deadliest kind

are discarded fishing lines and nets.

Each year, it's likely
over half a million animals

are ensnared and killed
by these ghost nets.

But some animals

are learning how to take advantage

of the plastic rafts...

...and use them for shelter
or even as a home.

This male Columbus crab,

barely bigger than your thumbnail,

is a castaway.

Clinging to his net,

he may have been drifting
on ocean currents for months.

Now fully grown,

he needs to find a partner.

But where?

Certainly not here,

alone on the net.

Columbus crabs are not good swimmers,

so this male is marooned.

Perhaps a passing loggerhead turtle

could be the chance to hitch a lift.

Made it.

But there is more than
one passenger here.

A female Columbus crab.

They waste no time
in getting acquainted...

...and start to mate.

This pair may well stay together

for the rest of their lives.

The turtle, after all,
makes an excellent home.

In return, the crabs provide
an onboard grooming service.

Finding a partner
in the vast ocean is not easy.

Dawn in the Sea of Cortez.

Mobula rays.

They're gathering here,
most likely, to breed.

No-one is sure why they leap,

but the loud splashes

certainly seem to attract more rays.

Other creatures, however,

are also listening.

Orca have heard the splashes.

This female specialises
in hunting rays.

But today she is teaching
two youngsters

the finer points
of mobula ray hunting.

The rays are fast and can
outmanoeuvre an orca.

She knows she needs to herd the prey

into a tight group.

But she can't do that on her own.

It'll take teamwork.

And that is today's lesson.

The young orca are quick to catch on.

The rays are surrounded.

They dive...

...only to be
forced back up again

by the experienced female.

And now,

with the exhausted rays
trapped against the surface...

...she attacks.

And the young ones follow her lead.

This family are the only orca
known to hunt rays like this.

And they are lethally efficient.

But it appears
that school is over for today.

For a few battle-scarred survivors,

it's a lucky reprieve.

With the orca gone, the rays
can resume their courtship.

And they do so in astounding numbers.

Tens of thousands of rays
in a single shoal.

Vast areas of our ocean
are yet to be explored.

The least known parts of it
are its great depths.

Only highly specialised vessels
can take you there.

As you descend,
the sunlight rapidly fades.

200 metres down,
you enter the twilight zone.

An alien world

inhabited by creatures
beyond imagination.

The siphonophore,

with a cloak
of lethal stinging tentacles.

Siphonophores
repeatedly clone themselves,

and so grow to immense lengths.

This one measures 45 metres

and is the longest animal
ever recorded.

With such deadly predators around,

creatures here
go to great lengths to hide.

A glass squid.

Completely transparent,

except for its eyes...

...and stomach.

So it is extremely difficult
to find in the gloom.

Below 1,000 metres,

all traces of sunlight
have disappeared.

This is the midnight zone.

Catching food
in the perpetual darkness

is not easy.

The gulper eel.

Its giant, extendable mouth

can engulf prey
larger than its own body.

Two miles down,

you finally reach the ocean floor.

We know more about
the surface of Mars.

The pressure of the water

is 300 times greater
than at the surface,

and it's freezing cold.

Yet, amazingly,
there are animals living here.

Muusoctopus robustus,

nicknamed the pearl octopus.

Breeding in these extreme conditions

poses a particular problem
for these animals.

At these low temperatures,

this female's eggs could take
over ten years to develop.

So she travels
to a very special place.

This is the largest known gathering

of octopus in the world.

She joins 20,000 other females...

...all here to lay their eggs.

Water, heated deep
in the Earth's crust,

rises through cracks in the seabed...

...raising the temperature to
as much as ten degrees Celsius.

A deep-sea thermal spa.

This warmth significantly speeds up

the development of their eggs.

Even so, they will still take
nearly two years to hatch.

Once a female is settled,

she won't move from her spot...

...not even to feed.

She will constantly tend to her brood,

keeping them clean...

...and oxygenating them
with jets of water.

Pearl octopus mothers

must surely be amongst
the most devoted.

After almost two years,

the ordeal takes its toll.

But the vigil is almost over.

The last of the brood are
gently encouraged to leave.

But this will be a final act.

Like all the mothers here,

this octopus is starved and exhausted.

Her life will soon be over.

But this devotion means
that her offspring

are among the largest
and most developed

of any octopus,

and have the best chance of survival

in the demanding world of the deep.

We are finding more
of these strange hot springs

every year.

In some places, they can be
astonishingly violent.

Superheated water,

hot enough to melt lead,
spouts from the sea floor.

Dissolved minerals
condense around them

to form towering chimneys
known as hydrothermal vents.

They are home

to unique communities of animals

that all rely on the nutrients
in the scalding water.

Some suggest that vents like these

could be the places
where life on Earth first began

4 billion years ago.

And there is now evidence
of hydrothermal vents

on the moons of Jupiter and Saturn.

Could they, too, be supporting life?

Here on Earth,
the influence of these vents

extends far beyond their chimneys.

The essential nutrients
carried in these plumes

can rise all the way to the surface,

two miles above.

Here, they stimulate the rapid growth

of tiny marine plants
on an astronomic scale.

This phytoplankton is so abundant

that it produces half
of all the oxygen on Earth.

It's also food for
a host of minute animals -

zooplankton.

Together, they are
the basis of the food chains

that sustain nearly all life
in the ocean.

In the Pacific waters
off South America,

they feed anchovy
that gather here in billions.

This is one of the world's
most productive ecosystems.

These South American sea lions
are on the hunt.

But the anchovy shoal
has already been located...

...by the planet's
most efficient hunters.

A net over half a mile long
encircles the shoal.

It can trap over a million fish.

But the sea lions
aren't about to go hungry.

They have learnt to look
for holes in the net.

Why waste energy

when food comes to you
as easily as this?

As more and more sea lions arrive,

some change their tactics.

They line up
on both sides of the net...

...and wait.

As the net tightens,

the anchovy panic
and rush for the surface.

This is the moment

the sea lions have been waiting for.

It's such an effective way of hunting

that the sea lions here

are changing
their natural behaviour...

...and are raiding
the fishing nets

in their thousands.

With the net almost drawn in,

the fishermen beat out
a warning signal.

Time is up.

In the confusion,
not everyone manages to escape.

The trapped sea lions are
in danger of being drowned.

Pups are separated from their mothers.

Then, at the last minute,

the fishermen
briefly drop their net...

...and the trapped sea lions
can escape.

But many are not so lucky.

Around the world,

millions of animals
are accidentally caught and die

in fishing nets every day.

And this by-catch, as it's known,

is pushing many species
toward extinction.

Animals have evolved
in remarkable ways

to the demands of life in the ocean.

But can they now adapt
to the new challenge -

living alongside us?