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.