All language subtitles for Planet Earth (2006) - S01E09 - Shallow Seas (1080p BluRay x265 Silence)

Our planet's continents
are fringed by shallow seas.

Rarely more than 200 metres deep,
they lie on the continental shelves,

which may stretch sometimes
for hundreds of miles

before the sea floor drops
into deeper, darker waters.

Altogether, they constitute
a mere 8% of the world's oceans,

but they contain the vast majority
of its marine life.

A male humpback whale sings to attract a mate.

The whales have just returned
to their breeding grounds

in the shallow seas of the tropics.

The calf is no more than a few weeks old.

Despite being three metres long
and weighing nearly a ton,

he is nonetheless vulnerable.

But his mother watches over him
and, as he begins to tire,

she supports him close to the surface
so that he can breathe more easily.

These shallows around the equator
are excellent nurseries.

They're warm, calm
and contain very few predators.

The playful calf is now drinking
500 litres of milk a day.

But his mother must starve.
There is nothing for her to eat here.

Like many tropical shallow seas,
these crystal-clear waters are virtually lifeless.

They receive year-round sunlight,

but they lack the nutrients
essential for the growth of plankton.

The mother will be trapped here
for the next five months

until her calf is strong enough to make
the journey to the feeding grounds near the poles.

Coral reefs are oases in a watery desert.

Most tropical shallows are barren,

but these coral havens contain one quarter
of all the marine life on our planet.

Reefs are the work of polyps,
tiny colonial animals like minute sea anemones.

Yet the Great Barrier Reef is so big
it can be seen from the moon.

It's actually 2, 000 separate reefs
that together form a barrier

stretching for over 1, 000 miles
along Australia's northeastern coast.

Despite its vast size, this reef does not contain

the greatest variety of marine life on the planet.

For that, one must travel north to Indonesia.

There are individual reefs in Indonesia
that contain almost as many kinds of fish

as live in the whole of the Caribbean.

There are also 10 times
the number of coral species.

Corals thrive in these waters
with the help of microscopic plants, algae,

that grow within the tissues of the polyps.

And the polyps feed by snaring
passing morsels with their tentacles.

At night, the algae are inactive,
but then the polyps put out even more tentacles.

So coral, in effect, feeds around the clock.

This well-balanced alliance
brings benefits to both polyps and algae,

and between them,
they turn the barren seas into rich gardens.

The Indonesian reefs contain such a variety of life
because they lie at a giant crossroads.

This is the meeting place for different seas,
the Indian Ocean and the Pacific.

Here, everything demands a closer look.

On the surface of this sea fan,
there are two polyps that are not polyps.

They're pygmy seahorses, the world's smallest,

less than two centimetres high.

They are males,
settling a territorial dispute by head-butting.

An electric flash?

No, the display of a file clam.

Perhaps this extraordinary pulsation
of the clam's fleshy mantle

is a warning to frighten away nibbling fish,
but no one really knows.

And there are snakes here, too. Lots of them.

These are banded sea kraits.

They lay their eggs on land
but they hunt here in the water.

They're too slow to catch fish in a straight chase,

so they seek prey that is hiding
in the nooks and crannies of the coral.

Their bite is highly venomous
and paralyses their victims.

And on this reef, the snakes do not hunt alone.

Shoals of yellow goatfish and trevally
are seeking similar prey,

and they attract the snakes' attention.

As one group of hunters searches the reef,
they are joined by the other.

At least 30 snakes have now joined the caravan.

The big fish scare the prey into cracks
and there the snakes can catch them.

And anything fleeing from the kraits

will swim straight into the mouths
of the waiting trevally.

There's nowhere to hide.

As the raiders scour the reef,
more and more snakes join the hunt.

This cooperation between snakes and fish,
spectacular though it is,

has only recently been observed,

for it only happens
on the most remote reefs in Indonesia.

Perhaps such hunting alliances
were once a common sight,

but today no more than 6%
of Indonesia's reefs are in their pristine state.

Beyond the coral
stretches a world of shifting sand.

Out there, with nowhere to hide,
survival is not easy and camouflage can be crucial.

If this wasn't moving,
you might think it was a shell or a rock.

In fact, it's an octopus.

A gurnard.
Its huge pectoral fins disguise its shape.

And they can also help in clearing away sand
when searching for food.

The jawfish hides underground.

The wonderpus octopus, on the other hand,
has such a powerful bite

that it has a special warning display
to tell others to keep out of its way.

Here and there, plants manage to take root
and they are cropped by green turtles.

Seagrasses are the only flowering plants
that have managed to grow in the sea.

Although they put out a few ribbon-like leaves,

they produce very extensive networks
of fleshy stems, rhizomes,

that are buried in the sand.

At their lushest, they can transform the seabed
into an underwater meadow.

The largest expanse grows in the shallow waters
of Shark Bay in Western Australia.

These vast aquatic grasslands
stretch for 1, 500 square miles.

And like terrestrial prairies,

they support herds of grazers, dugongs.

Dugongs are the largest herbivores in the sea.

They can be three metres long
and weigh half a ton,

and they eat nothing but seagrass,
mostly the fleshy rhizomes,

which they excavate with their mobile lips.

A herd can clear a patch of seagrass
the size of a football pitch in a single day.

Food is not evenly distributed in the tropical
shallow seas and it can take a lot of finding.

But bottlenose dolphins are inquisitive,
energetic and very intelligent

and they have discovered a shoal of bait fish.

Together they ride a wave,
using it to carry them into the shallows

and there it will be easier to make the catch.

In Western Australia, these dolphins
have taken on an even tougher challenge.

The fish have taken refuge close to the beach
where the water is only a few centimetres deep.

Tail-slapping is a method
dolphins often use to stun their prey,

but it doesn't seem to work here.

The fish are tantalisingly close,
but they're still out of reach.

So the dolphins try another technique.

Vigorously pumping their tails,
they work up some speed

and then they hydroplane.

Their momentum carries them right through
the shallowest waters and onto the fish.

Now they're in real danger of being stranded.

But fortune favours the brave.

Younger dolphins lie alongside, watching.

But, so far, only eight individuals here
have mastered this daring technique.

Although most life in tropical waters
is concentrated around the coral reefs

and the seagrass meadows,
there are some spectacular exceptions.

The desert of Bahrain seems a very unlikely place

to find a crowded, bustling colony of seabirds.

But every year,
100, 000 Socotra Cormorants gather here to breed.

It's swelteringly hot and only vigorous panting
can prevent the birds from fatal overheating.

This hardly seems a good place to rear young.

But at least
there are no land-based predators here.

The only source of trouble
is likely to be the neighbours.

So each nest is built just beyond pecking reach.

But what about food?

There's only bare sand
and the warm shallow sea beyond.

Neither seem likely to produce enough
nourishment to support birdlife on this scale.

The answer is blowing in the wind.

Sand whipped up by shamals, offshore winds,
blows into the seas of the Arabian Gulf.

With the grains come nutrients,
which act as fertiliser,

and they transform the shallow sea
into a rich fishing ground.

So, paradoxically, it's the roasted sands of Arabia

that prevent the Gulf from being
another desert in the sea.

The whale calf is now five months old.

He's almost doubled in size and his days
in his tropical nursery are coming to an end.

It has been a warm and safe place
in which to grow up,

but there's nothing to eat here for his mother.

She has been living off her fat reserves
for the last eight months

and she's close to starving.

She must leave now
while she still has enough energy

to guide and protect her calf
on the long voyage ahead.

All across the tropics,
humpbacks are heading away from the equator

towards the rich temperate seas of both
the southern and the northern hemispheres.

These are colder, rougher
and more dangerous waters.

Mother and calf must stay close.

They can send sound signals to one another
above the roar of the ocean

by slapping fins on the surface.

In winter, the temperate seas are lashed
by violent storms.

The turbulence stirs the water
and draws nutrients up from the depths.

But nutrients alone cannot support life.

There must also be sunlight.

In the spring, as the sun daily climbs
higher in the sky, the algae start to grow.

Blooms the size of the Amazon rainforest
turn the seas green.

Individually, the algae are tiny,

but together they produce three quarters
of all the oxygen in our atmosphere.

They're eaten by an array of bewildering creatures.

Salps appear in the plankton soup.

Individuals link together to form chains
which can stretch for 15 metres.

Pumping water through their bodies,
they strain out algae and other edible particles.

Comb jellies cruise through the water.

They, too, flourish in this seasonal soup

and for short periods
they appear in astounding numbers.

Krill, shrimp-like creatures.

By weight,
they're the most abundant animals on the planet.

A single swarm can contain
two million tons of them.

And that is a lot of fish food.

The shallow temperate seas support
the greatest concentrations of fish on our planet.

Huge shoals migrate
from their overwintering grounds in the depths

to feed in these rich waters.

It's these shoals that support
most of the world's sea mammals.

Sea lions have all the agility and speed needed
to collect what they want

and seemingly delight in doing so.

Dusky dolphin, often in pods 200 strong,

work together to reap the harvest.

They break up the shoals into smaller,
more manageable balls

and all the hunters benefit.

By midsummer,
the surface nutrients have all been absorbed.

The algae die and the food chain collapses.

In a few special places, however,

the temperate seas sustain these levels of life
throughout the summer.

Along the coast of California,
ocean currents carry a constant supply of nutrients

up from the depths to the surface layers.

These upwellings fertilise forests of giant kelp
that thrive in the summer sunshine.

The algal towers
are as high as a three-storey house

and they can grow by half a metre a day.

Life in the kelp is as full of drama
as in any other forest,

but the cast is less familiar.

An army of sea urchins is mounting an attack.

The urchin plague strikes at the kelps' holdfasts,
their crucial attachments to the rock.

Holdfasts are extremely tough,
but each urchin has five teeth

which are self-sharpening
and are replaced every few months.

Urchins fell vast areas of kelp forest,

creating clearings known as urchin barrens.

Yet "barrens" is a poor description.

Millions of invertebrates invade the seabed.

The most fearsome predator here is a giant.

The sunflower starfish is a metre across,

with an appetite for brittle stars.

It uses its feet to taste for prey.

When its actions are speeded up, it becomes clear

that the predator's fondness for the brittle stars

is almost matched by the brittle stars' ability
to get out of the way.

Sand dollars, flat sea urchins,
cluster together as a defence.

But it doesn't seem to work against
the sunflower starfish.

The predator extrudes its stomach
and wraps it around its victims,

liquefying their soft parts.

Nothing is left of them
except their white skeletons.

The Californian upwellings
are seasonal and relatively small.

But in southern Africa,
they're so big they create seas rich enough

to support colonies of over a million seals.

The Benguela Current sweeps along
the western coastline of southern Africa,

driving nutrient-rich waters up to the surface.

And then, at the southern tip of Africa,

it meets the Agulhas Current
arriving from the east.

The result? Even richer waters.

The seals here thrive on a diet of fish and squid.

In temperate seas,
there may actually be more squid than fish.

These are chokka squid
and they lay their egg capsules

in sandy shallows
bathed by the warmer Agulhas Current.

Each capsule contains a hundred tiny squid.

Within a few days, they develop spots of pigment

which, when they're adult,
they will use to communicate with one another.

With females continuing to lay eggs
and males still preoccupied with repelling rivals,

the squid drop their guard.

Stingray.

Short-tail stingray can be up to two metres across.

They're the largest of all the stingrays
and they have appetites to match.

Another predator is on the prowl.

The aptly named ragged-tooth shark.

Raggies grow to three metres long but they share
these waters with a shark twice their size.

The great white.

The largest predatory fish on the planet.

Each dawn,
Cape fur seals leave their colony to go fishing.

To reach the open sea,
they must cross a narrow strip of water

and that is patrolled by great whites.

Each seal is indeed swimming for its life.

The shark relies on surprise.

The great white's turn-of-speed
is powered by a high metabolism.

They only thrive in cold temperate seas,

for only these waters contain sufficient food
necessary to fuel such a ravenous predator.

As you travel towards the poles, North or South,

the colder, stormier seas can become even richer.

Midway between South Africa and the South Pole

lies the isolated island of Marion.

The island sits in the infamous Roaring Forties

where incessant gale-force winds
draw nutrients up from the depths,

ensuring plenty of food for King penguins.

The Kings are returning from a three-day
fishing trip with food for their chicks.

But first they must cross a crowded beach,

threading their way between gigantic
and bad-tempered elephant seals.

The 200, 000 penguins breeding here
are testament to the richness of the fishing.

King chicks are dependent on their mothers
for over a year

and this puts a great deal of pressure
on the parents.

Being flightless, the returning penguins
must cross the open beach on foot.

Fur seals that have come to the beach to breed
are waiting for them.

Fur seals normally live on krill,

but these have now acquired
an unexpected taste for blubber-rich penguins.

Penguins may be featherweights by comparison,

but they have razor-sharp bills
and a feisty character.

The seal could easily lose an eye.

The only safe way to grab a penguin
is from behind

and the birds are well aware of that.

Both animals are clumsy on this terrain
but the penguin has the more to lose.

Made it.

Two out of three penguins survive the seal attacks
and succeed in reaching their ever-hungry chicks.

The humpbacks are nearing the end
of their epic journeys.

After two months and thousands of miles,

they're entering the polar seas,
both in the north and the south.

In the far north, winter is over at last

and the ice is starting to melt.

The Aleutian Island chain,
running west from Alaska,

is the gateway to the Bering Sea.

With the retreating ice, rough weather
and ferocious currents stir up these shallow seas.

Add sunshine and the mix
is spectacularly productive.

Five million shearwaters have flown
almost 10,000 miles from Australia to get here.

In all, 80 million seabirds
come here for the summer,

the greatest concentration
to be found anywhere on Earth.

The humpbacks have finally arrived.

The giant shearwater flocks hunt the krill swarms,

sometimes diving to depths
of 40 metres to reach them.

A large humpback eats three tons of krill a day.

The polar seas in summer
are the most productive on the planet

and the whales gorge themselves round the clock.

The fat reserves they lay down now
will keep them alive during the year to come.

But it may not always be this way.

Fish and krill stocks are declining so rapidly

that spectacles like this
may soon be part of history.

Once the mother and calf have reached
their feeding grounds, they will separate.

With luck, the calf will make the epic journey
across the oceans

from equator to pole another 70 times,

cruising back and forth between the shallow seas

where life proliferates
so abundantly on our planet.