Original subtitles

It remained a mystery for a thousand generations...

capturing the imagination

of those who lived at its edge

but could not visit there.

Who could see only dimly into a shadowy world

both beautiful and bizarre.

Today, we can enter that world

and cast light on it.

Scientific explorers now seek to uncover

the secrets of this world.

Some of what we've learned seems remarkably similar

to the beliefs of Australia's aboriginal people.

They have endured for 50,000 years

by regarding themselves not above nature, but part of it.

Science often takes a different approach...

analyzing the living world by dissecting it

species by species.

But the aboriginals believe that no living thing

exists apart from the greater community of living things

that even the human is merely a part

of the great system of life.

Science is only now discovering

how much the aboriginals have long understood.

"It was unchanged through all of the time of my ancestors.

"From the dreamtime when animals were almost human

"and people were gods,

unchanging.

"The sea, the reef and all that lives here.

"But now, people are no longer gods

and change encircles us like the sharks."

The encroaching modern world is symbolized by vast settlements

such as Sydney, Australia's largest city.

But along the same coast lies an ancient underwater city

called by aboriginals Wogogaboo.

It is the largest structure on earth

built by living things.

The Great Barrier Reef.

More than 2,000 identifiable reefs combine

to form a rampart of coral 1,200 miles long

extending as much as 120 miles out to sea.

Erected over millions of years

it is a feature of earth's surface so immense

as to be visible from the moon.

In the great liquid space of the ocean

the reef's limestone ramparts and towers loom up

like a vast housing complex, providing its residents

with shelter from the surging sea

and from one another.

Like human cities, the reef is also a place

where the hungry can find a meal.

The concentration and interaction of life here

makes possible a steady exchange of life-giving nutrients

gathered from the surrounding sea.

Ironically, the massive reef system owes its existence

to tiny creatures called coral polyps.

Though these diminutive construction workers

are plant-like in appearance, they are animals

related to jellyfish and sea anemones.

They feed by capturing passing food in their tentacles

and protect themselves by secreting

a casing of calcium carbonate.

The calcium remains of the polyps

are compressed over time into limestone

forming the foundations

upon which new coral generations build.

An oasis in the desert of the open sea

the reef city attracts offshore travelers

like the gentle manta ray.

Such visitors enter a world of curious life-forms

where things are not always what they seem

a world where fish can inflate themselves like balloons

and an eight-legged creature, long portrayed as a monster

turns out to be remarkably intelligent and shy.

What appear to be ferns are instead, animals

sweeping the water for bits of food.

Here, some mollusks are jet-propelled...

and worms perform like Spanish dancers.

A creature shaped like a fierce snake

is actually a fish so wary it hides in a hole all day.

What appear to be feathers are poisonous spines.

A pink carnation is actually a worm.

The corals themselves exist

in an enormous array of shapes and configurations.

Many of these structures enable them to capture plankton

in barren tropical waters.

But to in ensure a steady food supply

some corals also grow their own food...

a microscopic algae

cultivated within the tissue of the cords themselves.

To provide their algae gardens with sunlight

corals take on unusual shapes.

The more surface area exposed to the sun

the better internal algae gardens grow.

As the coral generations accumulate

they rise toward the surface

creating a wall between land and sea

the barrier which gives this reef its name.

This upward growth is not without risk.

Occasional drops in sea level expose and kill the corals

turning reefs to islands.

One such tiny slip of land, Heron Island

at the southernmost end of the Great Barrier Reef

is home to a research station

operated by the University of Queensland.

Scientists from around the world gather here

to study the reef ecosystem.

In the station's labs, marine biologists seek to learn

how life transpires

in the world's greatest underwater city.

Perhaps the most important scientific research takes place

not in the labs, but on the reef itself.

Researches by the score visit the Great Barrier Reef annually.

Australians Valerie and Ron Taylor have devoted their lives

to underwater exploration and photography.

In three decades of diving here

they have helped reveal

the enormous complexity of reef life.

Although we dive the reef in the name of science

to study, photograph and count

the sheer beauty of the place draws us here

as much as the desire to better understand it.

The corals form a habitat

as lovely and magical as a fairy-tale setting.

For life here, though

the coral serves as a vital framework for survival

providing catch holds for attaching organisms

hiding places for prey and hunting grounds for predators.

A single square meter of coral can sustain dozens of species.

The coral polyps are the landlords

extracting as rent the organic debris of their tenants.

The tiny blenny keeps a wary watch

from the reef equivalent of an apartment.

Moray eels seek out crevices to occupy like day rooms.

Like many residents

the barramundi cod lays claim to a plot

and spends much of its time defending it from intruders.

Some creatures, like these bat fish

use the reef as a place to hover and rest part of each day.

Many of the fish that swim lightly through the day

commute beyond the reef at night to hunt

changing places with others that commute back

to rest all night on the reef.

The constant search for food permeates existence here.

Hunger can even lead small fish

to risk approaching a much larger stranger

in the hope of finding something to eat.

Offer food, and the fish flock like birds in a city park.

Not every creature here is a resident.

The jellyfish is a passer-by

occasionally swept over the reef as it rides the currents.

Most animals, like the shovel-nosed skate

seem timid in the presence of divers.

But the Taylors have learned to be on the lookout

for a notorious creature less likely to flee.

The abundance that draws divers to the reef

also attracts sharks.

Some sharks are permanent residents

who survive by being masters of deception.

The wobbegong, or carpet shark

has developed near-perfect camouflage

making it difficult to tell coral from carnivore.

It escapes the notice of enemies while lying in ambush for prey.

Because of their long experience diving the reef

the Taylors have often led scientific expeditions

to study the deepwater sharks lured

to this rich hunting ground.

Though frenzies are believed uncommon

sharks grow aggressive when food is on their midst

whether provided by nature

or by humans seeking to observe their behavior.

These bronze whalers provide a rare glimpse

of the streamlined power of animals fashioned by evolution

into beautiful and near-perfect hunters in the sea.

Patrolling the edges of the reef

sharks serve a vital function.

They eliminate the weak

and, over time, strengthen the breeds

of the very species they prey upon.

The history of the reef is a chronicle of constant change.

More than 25 million years ago

corals began to fringe Australia's eastern coast.

Across eons, ice ages lowered the sea levels

exposing and killing reef coral until the climate began to shift

and global warming melted the ice

allowing fresh veneers of coral to return.

Though most of the reef's story

remains hidden beneath the surface

we can more readily trace the history

of the scattered islands looming up from it.

When the seeds and spoors of life

reach these fertile outposts on the wind or currents

lush miniature worlds are born.

The islands provide both sustenance and habitat

for some of the largest bird colonies in the tropics.

The life of the islands is inextricably linked

to the encircling sea.

Nutrients are cycled from fish to bird to guano

fertilizing luxuriant vegetation.

These islands are also the birthplace

of another creature of the sea.

Each year, on summer's tides, under the protection of night

and ancient drama of reproduction unfolds.

From birth, sea turtles are ocean wanderers.

But at the age of 30, they begin to return every year

across thousands of miles of open sea

to reproduce young of their own

on the very same beaches where they were born.

After mating at sea

the female laboriously pulls herself ashore

where she digs an egg chamber in the sand.

In a single night, she will lay as many as 180 eggs

then cover them with sand and return to the sea.

The hidden eggs incubate over eight to ten weeks

protected by sand from sea birds and other marauders.

When the hatching emerge

instinct propels them toward the ocean

in a race to escape island birds.

Perhaps only one in a thousand of these hatchlings

will return in 30 years to reproduce...

enough to ensure the perpetuation of the species.

Beyond the marvels of ocean life

researchers are also making discoveries

that could yield invaluable products for human life.

Scientists are already finding species here

with immunities against many diseases.

The reef is a kind of living laboratory

where survival prompts exotic adaptations.

Juvenile fish

developed from eggs drifting in the currents

congregate near the reef.

When mature

they move out together as schools.

The shimmering array of fish

and the ability of every individual in a school

to instantly and simultaneously shift course

presents a disorienting target to would-be predators.

A diver roaming the reef will encounter

as many strategies for self-defense

as there are potential dangers in the surrounding sea.

For those creatures not blessed with great speed

a suit of armor can provide a portable hiding place.

For invertebrates such as the lobster

a shell serves a dual purpose as both shield and skeleton.

Lacking a shell of its own

the hermit crab turns an empty shell

into a kind of mobile home...

while the spider shell fashions a shelter camouflaged

to be mistaken for coral.

No method of defense is foolproof.

A crab suddenly caught in the open

is vulnerable to attack.

Opportunistic predators quickly zero in

on the crab's vulnerable underbelly.

The hard limestone casing secreted by corals

provides polyps with a secure shelter

impervious to most predators.

Yet, there is one devastating exception

the crown-of-thorns starfish.

Emitting digestive juices that kill polyps

the crown of thorns can wreak havoc.

In occasional population explosions

that ravage immense tracts of the Great Barrier Reef

the crown of thorns literally eats itself

out of house and home.

The crowded conditions of the reef

have prompted organisms

to develop elaborate chemical weaponry.

Nudibranchs, defend themselves simply by tasting bad.

To advertise their distasteful nature

and discourage predators

they've developed gaudy color schemes

illustrating a rule of the reef...

bright colors mean, "Don't eat me"

which may explain why there are so many colorful creatures here.

The florid beauty of the anemone can be deceptive.

Capsules on the tentacles of some anemones

fire poison darts

that paralyze anything, from plankton to fish.

Yet, small clown fish have adapted

to living within the deadly weaponry

protected by a mucous coat.

The clown fish escape predators

by remaining close to the stinging anemone

even using it as an egg nest.

In turn, the nearly immobile anemone

can capture and eat curious predators

lured to its side

by the presence of the tiny clown fish.

The lion fish displays the bright coloration

of a chemical warrior.

The feather-like spines contain a powerful toxin

capable of paralyzing or killing an attacker.

Among the most venomous

of all marine creatures is the puffer fish

best known for swelling up

to make itself difficult to swallow.

Many puffers also carry a nerve poison in their organs

so powerful that predators risk death

from respiratory paralysis if they eat a puffer.

The study of reef toxins has already shed light

on the nature of nerve and muscle disorders.

We may find

that substances deadly on the reef

can be turned by science

into remedies for human ailments.

At night, the mood of the reef transforms.

Shifts change in the reef city.

Herbivores that graze by day are replaced

by carnivores that hunt by night.

None is better equipped than the shark.

In complete darkness, the shark can locate prey

by sensing the electrical fields of quarry and homing in on them.

In the sea, the shark is master of the night.

For many creatures

night is simply a time of inactivity, and even sleep.

The crevices and corridors of the reef city offer

a profusion of hiding places for the drowsy.

To rest in safety

the parrot fish surrounds itself with a mucous cocoon

a transparent sleeping bag

that hides its scent from night hunters.

Too skittish to be approached closely in daylight

the creature is so docile at night

it can be examined carefully

then returned to its sleeping chamber.

Tentacles retracted all day by many corals

are now extended to sting and capture plankton.

The reef comes alive

with millions of Medusa-like tentacles.

A few nights each year

the Great Barrier Reef is the scene of a mass spawning

that may be unparalleled on Earth.

Billions of coral polyps

across thousands of square miles

spew a storm of eggs and sperm into the water

often within minutes of one another.

The floating blizzard of new life is attacked

by a frenzy of worms and countless tiny predators

but enough spawn survive

to create a new coral generation.

The spawn will drift far before sinking.

The progeny of one reef can ensure the future of others

far in the distance.

Lighthouses and markers reveal an ominous side of the reef.

Though a haven for sea life, it is a mortal enemy of ships.

Even steel hulls can be ripped open

by hidden coral heads.

There have been more than 1,200 shipwrecks

on the Great Barrier Reef in this century alone.

The freighter Cooma went aground in 1926.

To divers, its crumbling remains are a haunting reminder

that it once served as a human home.

Yet, to creatures of the sea

the sunken ship is merely a new building site.

Legions of polyps and other encrusting colonizers

gradually overwhelm deck plates and superstructures in a process

that will ultimately entomb the steel remains

beneath layers of life, creating an artificial reef

to be settled like a new suburb of the city.

Researchers have assumed a leading role

in the preservation of this ecosystem.

They have been directly responsible

for the protection of many threatened species.

Through the efforts

of many concerned people like the Taylors

the Great Barrier Reef was established

as a marine park by the Australian government.

The Great Barrier Reef

is a monument to life.

Tiny living organisms built it all,

created a reef larger than all the structures of Man.

We have only glimpsed the astonishing diversity

and complexity of its life.

We find wonder and beauty

in something as simple as a hermit crab.

It is important that we share that wonder

that we care for this priceless heritage

for ourselves, for our children

for all the generations to come.

We are learning more and more about the Great Barrier Reef

and the myriad species which exist within it.

Yet here, perhaps

we may learn most about our own species.

On the reef, we may learn whether we are only a predator

grown so powerful and uncaring

as to harm a magical realm of life

or whether, with all our powers

we have grown to respect life in all its forms

and to leave all its splendid torches burning.

All living things are one

like the blood which unites one family.

All of life forms one great web.

Man did not weave the web of life.

He is only a part of it.

He is only a strand within it.

Whatever he does to the web of life

he does to himself.