CARREY: The islands of
Papua New Guinea and Indonesia.
Here, volcanic gases
form undersea fountains...
and the sea erupts
with kaleidoscopic life.
The reefs surrounding these Pacific Islands
form the heart of the Coral Triangle.
More marine species live here
than anywhere else on Earth.
So many species live here
that they can all survive...
only if each is distinctly different
from the other.
This puppy-like creature
is actually an epaulette shark...
who lives only in the Coral Triangle.
He's not much of a swimmer,
so he prefers to crawl.
The Wobbegong Shark
looks like a shag carpet...
until he moves.
Disguised hunters need
almost endless patience.
Dinner must come to them.
A giant frogfish is hoping
the school of glassy sweepers...
mistakes it for a yellow sponge.
The crocodile fish blends
into the reef perfectly.
This time,
the Blue Damselfish was lucky.
But out of the frying pan
and into the fire.
Giant frogfish come in all colors.
Trying to hide under one
could be a really bad idea.
The stonefish is about as graceless
as a fish can be.
It has little to fear from predators.
No fish on Earth is more venomous.
It might wait several days
for a careless fish...
to swim within range
of that big ugly mouth.
After waiting so patiently...
that must be frustrating.
But the most venomous creatures here
are not fish.
That distinction belongs to sea snakes.
Their venom is many times more potent
than a king cobra's.
Like other snakes, these breathe air...
but they can dive more than 100 feet,
and stay down for hours.
Sea snakes are increasingly rare,
even here in the Coral Triangle.
Most have become wallets,
shoes or handbags.
In the Coral Triangle,
mangroves fringe most shorelines.
These coastal jungles protect islands
from erosion...
and provide a buffer against storms
and even the occasional tsunami.
The labyrinth of mangrove roots...
captures sediments
washed down from the islands...
keeping the coral reef
from being smothered in silt.
The maze of roots is a shadowy habitat
for many creatures.
A swarm of Striped Catfish
feeds on algae growing on the roots...
and on the silty bottom.
This silt settles in bays...
forming vast plains
of organic debris, sand and muck.
And if you think nothing could live here,
you might be surprised.
The catfish school cascades across
the mucky bottom like a breaking wave...
as fish feeding in the front
are passed over by those in the rear.
Like most animals living here...
the stingray conceals itself
by hiding beneath the muck.
Dude, I can totally see your tail.
The goby is an excellent watchman,
but not so good at cave building.
He leaves the heavy construction
to his partner and personal contractor...
the nearly-blind shrimp.
The relationship is called symbiosis.
Both animals think they have
a pretty good deal.
A carrier crab is looking
for his own symbiotic partner.
He's happy to find a jellyfish...
which he decides to wear
as a protective hat.
This is a love triangle.
Flamboyant Cuttlefish.
The 2 small ones
are the hopelessly devoted males.
The female is the larger one,
but they would never tell her that.
They can swim well enough, but usually
prefer to gallop across the muck...
on the tips of their fleshy, little arms.
Their mating embrace
is little more than a peck on the cheek.
The male simply passes the female
a tiny packet.
Or, at least he tries to.
Whether she'll accept is another matter.
That's all there is to it.
Deeper in the bay,
a school of reef squid...
fashion a bouquet
of translucent egg cases.
Male squid hover nearby
as females move in...
and add to the cluster.
In about 3 weeks,
the egg casings will begin to burst...
each releasing a half a dozen
or so jewel-like miniatures.
The baby squid will then
drift away across the sandy plain...
to take their chances.
A field of garden eels towers over
the sea floor.
Some rise more than 6 feet...
reaching high to snap up tiny animals
adrift in the current.
Above the reef, a swarm of baby
convict fish forages over the coral.
Then, in late afternoon,
they all gather over a burrow in the sand...
that serves as home.
The dark creature emerging
from the borough is an adult convict fish.
Her brief appearance may be a signal,
beckoning her children home for the night.
But before sleeping,
the babies have one important chore:
They must feed their parents.
The pair of adult convict fish
never leave their den.
And what they eat is a mystery.
Some scientists believe the babies feed
their parents a form of secreted slime.
But others think mom and dad survive...
simply by eating
a few of their children every night.
As evening deepens,
reef cuttlefish are on the hunt.
They communicate with instantaneous
changes of color, pattern and texture.
Their ability to hover without effort...
is aided by a porous calcium-carbonate
structure beneath their skin.
This cuttlebone
gives the creature buoyancy.
Cuttlefish are aggressive hunters.
They strike with blinding speed...
shooting out a pair
of lightning fast tentacles.
A piercing tongue covered
with razor-sharp teeth...
waits to gnaw the fish to bits.
South of the Coral Triangle lies
the largest living structure on Earth...
Australia's Great Barrier Reef.
This most recent version
of the Great Barrier Reef...
began growing about
at the end of the last Ice Age.
Then, sea levels were 400 feet lower
than they are today.
As the ice began to melt, the seas rose.
Corals grew on top of coral...
building undersea mountains
made of limestone or calcium carbonate.
Corals grow by combining
carbon dioxide and sunlight.
But the balance of carbon dioxide
in our atmosphere is critical...
especially to coral reefs,
and the creatures that call them home.
Every animal here depends on another
in some fashion.
This potato cod
is ready for her beautician.
And let's face it, when you're a cod,
you need all the help you can get.
Cleaner fish provide a gentle service
no self-respecting cod can be without.
While giving her a facial,
the cleaners eat parasites.
And in exchange, the potato cod
resists the temptation to gobble them up.
Another good deal.
A crown jellyfish slowly pulsates...
forcing tiny animals to pass
through its stinging tentacles.
When the current carries
a jellyfish into the reef...
butterfly fish join up.
Even if it makes their little lips sting.
Some creatures
are not satisfied with only a taste.
Green sea turtles love to fill their
cast-iron stomachs with venomous jelly.
As the turtle devours its prey...
it carefully closes its eyes to avoid
the sting to sensitive corneas.
The eastern edge
of the Great Barrier Reef...
plummets into the depths
of the coral sea.
Many deep-water creatures gather
on these undersea escarpments.
A chambered nautilus bobs its way
toward deeper water.
Its shell contains gas-filled chambers
that can withstand tremendous pressure...
and its primitive eye is little more than a
pinhole in front of the light-sensitive retina.
Like the coral reef itself...
its strong shell
is made of calcium carbonate.
Once, over 2,000 species of nautiloids
dominated life under the sea.
But that was long before
dinosaurs roamed the planet.
And the climate above and within the ocean
has changed many times since.
Today, only 6 species of nautilus
haunt the deep sea.
Sudden changes in climate can exterminate
species that cannot adapt quickly.
Corals need carbon dioxide to grow...
but we're putting so much
of it into our atmosphere...
that it's causing
global temperatures to rise.
If sea water gets too warm,
coral reefs bleach white and die.
But even more deadly
is a new threat called ocean acidification.
Too much carbon dioxide inhibits
the formation of calcium carbonate...
the stuff coral reefs are made of,
and the shells of the chambered nautilus...
the cuttlebone, and the skeletons
of thousands of other species.
Many animals could become extinct.
Coral reefs could begin to dissolve.
As temperatures rise, many species
can move south toward cooler waters.
The dwarf minke whale spends its winter
in the Great Barrier Reef.
Then in the spring, it heads south
to the cold waters of the Southern Ocean.
Cape Catastrophe, South Australia.
In these cold waters
lurks an ancient leviathan...
one of the ocean's
most magnificent hunters...
the great white shark.
Great whites often reach
A shark that large
may weigh more than a ton...
and can easily make a single meal
out of a 200-pound sea lion.
Sea lions must remain constantly alert.
The world's largest stingrays
also hunt here...
searching for crustaceans and mollusks
hiding beneath the sand.
The rays often travel
with their own entourage...
a squadron of opportunistic fish...
ready to pounce on small animals
frightened from their hiding places.
Most of the time, the great white shark
will ignore a stingray.
But not always.
Great whites have often been found
with foot-long stingray barbs...
embedded in their jaws.
Australian sea lions are among
the rarest of marine mammals.
Once hunted relentlessly,
now only 10,000 or so remain.
They seem to be the most carefree
of creatures.
But as global temperature rise...
the animals living in South Australia
have nowhere further south to move.
Each year in these shallow gardens,
giant cuttlefish gather for spawning.
They are the largest cuttlefish
in the world.
Males sometimes reach
more than 3 feet in length.
Giant males confront each other,
competing for females...
hiding in the yellow sponge below.
These confrontations seldom result
in serious violence.
Instead, males puff themselves up
and look as menacing as possible...
then communicate
their willingness to fight...
with angry displays
of color and pattern.
As the big males compete...
smaller males, called sneakers,
disguise themselves as females.
Then, cloaked in feminine charm...
they slip past
the dueling giants unchallenged.
Females seem to find
the cross-dressing males quite attractive.
Sneakers are
surprisingly successful lovers.
Giant cuttlefish mate face to face...
in a tangled embrace
that may last many minutes.
The urge to find a mate is strong
but this cuttlefish is hungry.
The crab's sharp claws
cause the cuttlefish to hesitate.
No one likes to be pinched in the face.
But a crab dinner
certainly seems worth it.
A female has deposited her eggs
in a crevice beneath the reef.
This is her final act.
In the next few weeks...
all of the adult male
and female cuttlefish will die.
Giant cuttlefish live only 2 years.
But these have left their legacy.
In about 4 months,
these eggs will hatch...
and a new generation of giants
will inherit this undersea garden.
Swarms of mysid shrimp roll over the reef
like a mountain fog.
These tiny shrimp become food
for many species.
One is among the most bizarre
of all ocean creatures.
The weedy sea dragon...
is one of only 3 species of sea dragon
that exist on Earth.
He propels himself by undulating
tiny transparent fins on his back...
and on either side of his head.
The dragon slurps his dinner
with a long tubular snout...
that's perfectly designed
for capturing tiny shrimp.
The other dragon living here...
defies even
the most fertile imagination.
The leafy sea dragon.
He has turned camouflage
into an exquisite work of art.
Sea dragons seldom venture
far from home.
Indeed, these delicate creatures
are not designed to swim fast or far.
As the climate changes...
undersea gardens
in the gulfs of South Australia...
are beginning to die out.
When these gardens disappear...
the dragons must vanish with them.
But there are hopeful signs
of an even greater change taking place.
It's a change within us.
We finally seem ready
to accept the responsibility...
for the changes we are causing
to our atmosphere...
our oceans, and our planet.
We have the skills.
If we apply them,
our legacy could be an ocean wonderland...
where dragons still roam...
and where sea lions are forever at play.