All language subtitles for 6) -2001- The Blue Planet-Coral Seas

In all the seas of the world,
the warm waters of the tropics

contain the richest
and most colorful communities.

Coral reefs.

They may seem
like underwater paradise,

but they are perpetual
battlegrounds for space.

Even the corals
have to fight for it.

In this crowded frenetic community,
every individual needs its place,

its own way of surviving.

None of these creatures would be
here if it were not for the coral.

A coral larva
drifts in the open sea,

floating in a soup
of young reef animals.

If just one of these coral larvae
survives in a suitable spot,

a new reef will be founded.

In just a few days,
the larva changes form

and becomes a polyp,
similar to a sea anemone.

Identical copies bud off
and, gradually, a colony develops.

Each polyp surrounds itself
with a hard skeleton,

and, from this solid base,
begins to grow.

It increases in length
by an impressive 15cms a year.

This branching coral
is only two years old.

A mature reef can be thousands.

Corals provide the foundations

on which the entire
reef community relies.

Some organisms,

like the Christmas tree worms,
actually live within the coral.

Others climb out,
away from the reef,

to filter their food
from the water.

As the community grows,

intimate relationships form,

and different creatures
become dependent on one another.

Even animals that spend much
of their time traveling in the ocean

return to the reef for a clean.

Coral reefs can be home
to astounding numbers of fish.

Here swim the smallest
and the largest fish in the sea.

Whale sharks are only visitors.

When currents bring nutrient-rich
water up from the deep,

they come here to feed.

All these animals are here

because of the coral.

This extraordinary complex maze
is built, layer upon layer,

by millions and millions
of individual animals -

polyps.

Each polyp's flesh is supported
by a limestone skeleton.

Below the gut...

...is the place
where most of the growth occurs.

Here, the living tissue deposits
an intricate lattice of limestone.

Beneath that,
the limestone skeleton is bare,

having been vacated
by the living coral tissues.

This is the hard structure
that forms the foundation of the reef.

A single reef can extend
for many miles.

Coral reefs are only found
in the clear, warm,

shallow waters of the tropics.

Sunlight is vital to them,
even though they are animals,

because inside their flesh live
millions of tiny single-cell algae,

plants.

And all plants need sunlight
to photosynthesize sugars.

98 percent of the food the corals consume
is produced by the algae.

Without them,

the reef would not exist.

Like any plant, algae need
just the right amount of light.

Not too much, not too little.

The corals regulate that
with pigments that we can only see

when they are illuminated
by ultraviolet light.

Most corals, for protection,

spend the day withdrawn
into their stony fortresses.

Even then they are not safe
from the jaws of these butterfly fish.

At night, the corals take in water,

expand their tentacles
and emerge to feed.

They collect plankton.

Each tentacle has stinging cells,
which fire on contact.

Once the prey is caught, it's passed
down to the polyp's mouth.

It is at night,
when the polyps are extended,

that they add to the limestone
foundations beneath them.

Inevitably, the corals
begin to overgrow each other,

and that means trouble.

When neighbors get too close,

they detect
one another's presence chemically.

The aggressor on the right
prepares for battle.

The polyps extrude their guts

and simply
digest their rivals alive.

A no-man's-land -
a band of white skeleton -

is the only evidence
of the night's border dispute.

Some corals are targeted
by yet more deadly predators.

Predators that can crawl
in search of their victims.

Crown of thorns starfish -

poisonous,
invincible eating machines.

They also extrude their gut
and digest coral Wholesale.

But some corals have help.

Small crabs living within their
branches resist these onslaughts

and defend their home.

From beneath, they launch an attack

on the vulnerable underside
of the starfish.

Even the crown of thorns
will retreat

from such a determined attack.

This coral is left unharmed.

Humphead parrotfish,
nearly a meter and a half in length.

Their jaws are so powerful
they can bite through rock.

When they descend to feed,
the reef itself is under threat.

They are indiscriminate feeders,

taking both rock and coral alike
in their quest for algae.

These fish play a large part
in the erosion of the reef.

The rock and coral emerges later
as a fine sand.

On a single reef, they can produce
tons of it every year.

This soft sand
forms the tropical beaches

that we find so alluring.

Over time, the sand builds up
to form an island,

which is then colonized
by animals and plants.

Trees take root.

Birds arrive.

The guano from thousands of terns
which have chosen to nest here

enriches the sandy soil,
which then can support more plants.

But these terns,
like other seabirds,

depend on the ocean for their food.

Below water, there is not only
competition for living space,

but a continual contest
between predators and prey.

It's the arms race between them
that over millions of years

has produced today's
extraordinary diversity of form.

Jacks are one of the key predators
on the reef.

Their weapon is speed.

They seek silversides,
whose defense is to congregate

in confusing shoals
of shimmering silver.

The jacks deal With that by herding
the silversides onto the reef.

Here, the jacks
have a better chance

of separating individual fish
from the shoal.

The jacks can now catch
the isolated individuals

with lightning attacks.

It's far safer to be hidden
on the reef itself,

within the tunnels of a sponge,
for example.

These tiny shrimp are no bigger
than grains of rice.

These shrimps are unique.

It's recently been discovered

that they have
a highly-sophisticated social system,

similar to that of bees.

All members of the colony
are the offspring of one female.

She is the queen
and the only one to produce eggs.

As in a colony of bees,

different individuals are
specialized for particular tasks.

Some are guards and are armed

with particularly
large and powerful claws.

They are on watch at all times,
ready to tackle intruders.

A polychaete worm. For it, a sponge
is an excellent hunting ground.

In such a maze of tunnels,
attack can come at any time

from any quarter.

Once the guards are alerted,
the worm loses its advantage.

Better to retreat intact
than risk serious injury.

The sponge not only makes
a safe home for the shrimps,

it also supplies them with food,
so they never need venture outside.

An establishment that provides
all their needs

is clearly well worth defending.

Just as shrimps guard their home,

other animals defend
their hunting grounds.

Glassfish make tempting prey
for the redmouth grouper.

Its strategy is to swim
slowly amongst them

till they no longer see it
as a threat.

There are other fish here, too.

Lionfish are ambush predators,

taking their time
and watching for the right moment.

But there isn't room here
for two predators.

The grouper, braving the lionfish's
poisonous spines,

tries to evict its rival.

But lionfish are persistent.

This grouper spent many hours
simply defending his hunting patch.

Some animals prefer to avoid
conflict whenever possible.

These harlequin shrimp,
having captured a starfish,

are taking it back to a safe house

beyond the reach
of competitors and danger.

The problem is that starfish
have minds of their own

and five large sticky arms.

By the time the shrimps
have prized off one arm,

another has reattached itself.

Only by maneuvering
the starfish onto its back

can they have any hope
of gaining the advantage.

Even so, getting it back home

is a major undertaking.

The starfish
is now a living larder.

If the shrimps can hang onto it,
it will feed them for days to come.

The top of the reef
is usually covered

by a thin layer of green algae,
another living larder.

And many fish depend on it.

Powder blue tangs
defend their right

to graze on a particular patch.

But, for a larder as well stocked
as this, there is always competition.

When a shoal of convict tangs
decide to graze,

little can stop them.

The powder blue tangs
try to keep them off...

...but they are overwhelmed
by sheer numbers.

The territory is stripped of algae
in minutes.

The blue tangs appear
to be fighting a losing battle.

But, eventually,
they begin to get the upper hand.

They persist with their attacks

until the marauders
are well on their way.

When night falls, some very strange
creatures creep out of crevices

and crawl over the reef.

This moving bush is an animal -

a basket star -

which spreads out its arms
to catch the night's plankton.

The reef becomes
uncannily tranquil.

Fish retire, hiding themselves
where they can.

Marbled rays come out to hunt
for prey buried in the sand...

...using electro-receptors
to scan the seabed.

Their activity attracts sharks.

White tips.

At night, when vision is of little use,
sharks have a real advantage.

They can still use both smell
and electro-reception to track fish.

These sharks are also hunting
for fish concealed Within the reef.

Their slender shape

enables them to squeeze
through surprisingly narrow gaps.

There is nowhere to hide.

Few animals are safe
during these feeding frenzies.

Night after night, the reef animals
are subjected to these raids.

But life on the reef
is not just about food,

it's also about sex.

There are many different
breeding strategies,

but each is aimed at maximizing
the number of young that will survive.

Every afternoon for two months,
brown surgeonfish can be seen

streaming across reefs
in the Red Sea.

They all head for the same place,

usually some prominent feature.

Here, they wait
for the light to fade.

Suddenly, females Within the group

make a dash away from the reef
to release their eggs.

They're followed
by the quickest and closest males,

all of whom are striving
to fertilize the eggs.

Inevitably, others come here
to feast on such easy food.

As the surgeonfish spawn,

fusiliers move in above
to eat the nutritious eggs.

These are just the first
of many predators which will feed

on the eggs and developing larvae

as they drift
during the next few weeks.

Other fish are less casual
about their eggs.

Banded pipefish stay close
to a small chosen area on the reef.

Every morning at sunrise,
the female leaves her sleeping site

and swims to find her partner.

For ten minutes or so,
they remain together,

reaffirming the bond that is
essential to their partnership.

They swim together
around his territory

in a simple greeting dance.

Throughout the summer,
when the female 's eggs are ripe,

courtship begins in earnest
in the early morning.

It takes time. After about two hours,
they rise off the seabed,

entwining their two bodies.

The male rubs himself
against the female,

stimulating her
to release her eggs.

And now, swiftly,
the male takes them.

The eggs, now stuck to his belly,

are patted down
to ensure that they stay there.

The female then leaves him,

but, every morning, returns for
a session of synchronized swimming

and so ensures
that their bond is maintained.

Ten days later, under the cover of
darkness, the male shakes his body

and the young pipefish are born.

Only now are they
independent of their parents.

Since the male takes charge
of the eggs as soon as they are laid,

the female can start
producing the next batch.

Without his help, the pair could
only breed every 20 days,

rather than every ten.

By sharing the work, they double

the number of young
they can produce in any one year.

A flamboyant cuttlefish.

Unlike most cuttlefish, this one
spends much of its time walking,

rather than jetting
across the seabed.

This is a male.

He is using his colorful display

to try and seduce the larger female,
who seems unimpressed.

Eventually, she concedes.

The final event, the transfer
of sperm, is very quick.

(WHALE SONG)

A singing male humpback Whale.

Humpbacks are only visitors
to the reef.

After a pregnancy
that lasted a whole year,

the females come here to give birth
and suckle their newly-born young.

Their investment in their single
offspring is considerable,

for each female
will continue to nurse it

for a further six to 12 months.

But the males are here to mate.

The lone males sing to establish
their relative seniority.

The louder and longer the song,
the bigger and stronger the singer.

The better the song,
the larger the male,

the more mating opportunities
he will get.

All these different mating
strategies have the same aim -

to ensure that the greatest
possible number of offspring

will live long enough
to breed themselves.

Corals also reproduce sexually,

but being fixed to the seabed,
they can't move to find a mate.

Somehow, they must synchronize
their sexual activity.

They do so using the rising
water temperatures of spring

and the phases of the moon.

A few days after the full moon
in late spring,

when tidal currents
are at their weakest,

the corals of the Great Barrier Reef
are ready to spawn.

Some corals are male
and release clouds of sperm.

Nearby, a female
will be releasing eggs.

Other species of coral
are both male and female.

These release packages of eggs

already pre-wrapped in sperm.

Bundles of eggs and sperm
float to the surface

to mix with others
from further along the reef.

Each kind of coral
times its release

to a certain hour
on a certain night.

That maximizes the chances
for cross-fertilization.

The fertilized eggs

drift away from the reef.

The stormy season brings real
danger to the animals of the reef.

Lobsters in the Caribbean
sense a change in the water.

The temperature drops and powerful
swells disturb the sand.

Under the cover of darkness,

they emerge to run before the storm

and risk crossing
the exposed sand flats

to seek shelter in deeper water.

Every year they make this journey.

From all over the reef,
lobsters come to join the march.

They conserve energy by traveling
in one another's slipstream.

And there is the added benefit

of safety in numbers.

By daybreak, they've reached
the edge of the deep reef

and down they go.

For the rest of the stormy season,

they will remain in the shelter
of deep water,

out of harm 's way.

Sometimes, during the stormy
season, a hurricane builds.

Then the very structure
of the reef itself is under threat.

An entire reef can be destroyed
by just one big storm.

Hundreds of years of growth
gone in a few hours.

Out in the ocean,
new life continues to develop.

In time, coral larvae will return
to colonize the rubble

and a new reef will grow
on the wasteland.