Original subtitles

Australia's ocean wilderness is one of the most extraordinary places on earth.

It is both beautiful and bountiful.

It starts with the tiniest fish, which in turn

support an astonishing array of larger creatures.

Dusky sharks are fast, streamlined predators,

that can grow over four metres in length.

Dense schools of sardines on this Western

Australian coastline attract their hungry mouths.

The fish are fast, and their quick shimmering changes in direction make it

hard for the predators to pick out an individual.

The fish are also very fast.

Their prey are herded towards the shallows.

In the shallows, there's also a group of young board riders.

Confident that the sharks are keeping themselves busy,

the swimmers have entered the fray for a close encounter.

There are 375 shark species in the world, yet

only three are responsible for most human attacks.

Dusky sharks are not amongst them.

More and more sharks join the feast, drawn far and wide.

Far

up, the sheer size of the scene becomes clear.

They have begun one colossal bait ball.

A seething mass of predators and prey spreads along the coast.

In scale, rarely seen anywhere else on the planet.

The abundance of fish still teeming in

Australia's oceans supports many marine predators.

But not all of them remain underwater.

Just over 60 kilometres off South Australia lies Pearson Island.

Often compared to the Galapagos, this island is the most popular.

It's archipelago has a precious cargo of species found nowhere else on Earth.

The Australian sea lion is amongst the rarest of its kind in the world.

Its population reached dangerously low levels

after being hunted for close on two centuries.

The world's least polluted and best stocked

waterways have helped sea lions to survive.

The island's back from the brink of extinction.

These are ideal fishing grounds for a sea lion mum.

The island's small sandy bay provides the perfect nursery for her pups.

He's not confident enough to follow his mother into the waves just yet.

Alone, he watches the more experienced youngsters mess about in the water.

Perhaps

someone close to his own age will provide some company.

But mothers can be protective.

And fathers horribly hostile.

The colony can be a dangerous place to wander in search of a playmate.

Mothers come ashore and reunite with their pups for a feed.

But his wait continues.

In Pearson Island's Toddlers Pool, the young pup has finally found a friend.

From a different species, a long-nosed fur-sealed pup.

These rock pools at the back of the bay provide the perfect playground.

Hunger

grows, he watches.

And his mother's return.

Sea lions are some of nature's greatest ocean acrobats.

So simply coming ashore should be easy.

She needs to pick a landing spot.

But the crashing waves are making it hard.

If she's not going to clear a wave in time, she

needs to abandon the plan for a wiser future.

The sandy beach is surely an easier landing site.

As fast as his flippers can carry him, the pup

runs to his mum, and finally gets his milk.

He will rely on his mother for 18 months before he

must catch his own dinner like the older mother.

And he will be back to the sea lions.

One of the reasons sea lions can thrive in the seas

around southern Australia is the abundance of prey.

And now, in winter, one of their favourite foods is starting to mass in one of the

most intriguing and graceful animal congregations known only in these waters.

In the wide shallows of Spencer Gulf on Australia's south coast, as the water

temperature drops below 12 degrees in winter, a magical phenomenon takes place.

Giant cuttlefish up to a metre in length are found only in Australia.

Masters of disguise, they can change the colour and

texture of their skin to blend with their surroundings.

At this time of year, though, it's all about standing out from a crowd.

This patch of reef, just over a square kilometre in size,

has been inundated with thousands of courting cuttles.

With a ratio of 11 males to every female, not every male is going to get lucky.

This female has accepted the protection of a larger male.

But now he must hold on to his mating rights in

the face of constant challenges from eager rivals.

The males quite literally size each other up.

By splaying out his tentacles, turning white, and angling his body at 45

degrees, this alpha male attempts to appear larger than his challenger.

The female is hidden below, while waves of black add to his display of strength.

As rivals converge on either side, it's

almost impossible to keep his mate concealed.

While the alpha male is distracted, his mate drifts from cover.

A smaller male sees an opportunity and moves in.

The interloper drags her as far as he can,

before forcing her into his twisted embrace.

But the larger alpha male is quick to reclaim his prize.

But the larger alpha male is quick to reclaim his prize.

Like a fire hose, he flushes out the sperm of previous copulators.

As the last to mate, he will be the one to fertilize her eggs.

The pair can finally get down to the business of finding a place to nest.

Any prospective home for their eggs requires close inspection.

Satisfied, she begins depositing their first clutch.

It takes around six minutes before she can lay another egg.

So the male must guard her closely.

It's a prime nesting place, coveted by other cuttles, who

feel their way closer to the crevice and the fertile female.

One by one, the delicate nest begins.

The eggs are fixed.

To stop others entering the cave, he flattens

his body, making him appear even larger.

Doing his utmost to impersonate a monstrous kraken.

Males venture closer, testing his resolve.

His fatherhood is on the line.

It's a warning sign.

Stay away from this monstrous lair.

Despite the show of brute strength, challenges persist.

The monster allows them even closer.

Until...

Cuttlefish expel ink to confuse predators.

But this is a desperate attempt to escape the clutches of one of their own.

The largest male on the reef.

This unique marine spectacle was on the verge of being lost.

In a single season, commercial fishermen caught

240 tons of cuttlefish at this breeding site.

Before a fishing ban was put in place.

Today, these calm inshore shallows allow this

amorous gathering to continue in relative peace.

While further out to sea, storms are brewing.

In the depths of winter, polar winds from Antarctica

whip up huge swells across the Southern Ocean.

This is the ocean's engine room, generating waves that will roll across the planet.

And Australia's southern coastline is shaped by this powerful force.

As the ocean swell nears the outer fringes of Australia, huge waves as high as

seven-story buildings have been recorded off Tasmania.

In winter, many of the ocean wanderers leave this violent seascape.

To seek refuge in the great Australian Bight.

The arid Nullarbor Plain reaches a dramatic end

as land plummets to the ocean 150 meters below.

Every year in winter, southern right whales gather in these cliffside coves.

This female left her feeding ground in the Antarctic

and traveled over 4,000 kilometers to give birth.

The warmer water is gentle on her newborn, yet to grow its insulating blubber.

She will nurse her calf here until it's strong enough

to face the long migration south at the start of spring.

But it's not all gentle play for whales in these waters.

These cliffside coves are the arena for spectacular mating events.

At nearly 15 meters and each weighing as much as

100 tons, four males close in on the lone female.

Dolphins become curious on the host.

Females are known to go belly up in an attempt to keep their genitals away from

males as they wield their supersized anatomy.

Almost four meters long, the penis of the

whale delivers a gallon of sperm during mating.

Unlike the southern right whales, this dolphin

pod remains by the coast throughout the year.

And despite the size difference, the dolphins are

happy to share their home with the visiting giants.

The whale even appears to mimic its more agile playmates.

Play is the most important thing.

It tends to be a preoccupation for most of the mammals in the southern seas.

In mid-winter, surfers also take to the water.

It's a time when waves are often at their best because of the southern ocean swell.

And when the surf picks up, it's not just people trying to catch a wave.

It's also the dolphins.

Reaching up to 50 kilometers an hour, they rocket through the waves.

Research has shown that these synchronized displays help male dolphins form alliances.

Of course, surfing is also fun.

While dolphins frolic below the water's surface, there are far darker goings-on.

Port Phillip Bay is on the doorstep of Melbourne.

But very few of its residents, including me, have ever witnessed the

eerie marine spectacle that mysteriously unfolds

in these shallows for a few weeks every winter.

At nearly half a meter in width, giant spider

crabs are amongst the world's largest crustaceans.

Seldom seen, they spend the years scavenging on the seabed.

But this crab's spider senses are tinkling.

It's time for a change.

It's soon joined by others.

Normally dwelling in depths of up to 800 meters,

these crabs migrate to the shallows each winter.

Not to mate, but to molt.

To shed their old shells.

It's believed the winter's drop in temperature triggers this mass migration.

Before long, the ocean floor is writhing with a carpet of

claws and spindly legs, sometimes several creatures thick.

In the world above, life continues as usual.

While just a few meters below, thousands of giant spider crabs are

entering the most vulnerable stage in their lives.

A scratching at its face is a sure sign this crab's transformation has begun.

In order to grow, the crab must remove its old shell and reveal a new one beneath.

Its new orange shell, though larger, is flexible

and able to bend as the crab works its way out.

However, this temporary softness will prove its downfall.

It's one of the first to expose its new soft shell.

And its hard-bodied neighbors waste no time in seizing an opportunity for a meal.

When growing a new shell, crabs need as much protein

as they can get, no matter how macabre the source.

Once a leg is plucked from a victim, the attacker quickly retreats with its prize.

Despite the perils of molting in the midst of

cannibals, these crabs are playing a numbers game.

There's a greater threat to their kind.

Smooth stingrays armed with venom-tipped

tails have stalked the crabs to the shallows.

These are the largest stingrays in the world.

But they have no need for toxic barbs here.

Swooping over the scrum of panicked shellfish, the ray vacuums up the crabs.

Defenseless crustaceans are sucked from their soft shells.

Which

continues well into the night, the rays gorging themselves to bursting point.

Yet, with this many crabs molting at once, even

the most insatiable rays can't eat them all.

But then, a week or two later, just as suddenly as they arrived, they are gone.

Disappearing back to the deep, where their lives largely remain a mystery.

A few leftovers from the feast of rays are all that remain.

One reason for Australia's many marine marvels

is that one, the southern ocean chills the south.

Two more oceans bring warm tropical water from the north.

In the west, it's the Indian Ocean.

In the east, the mighty Pacific.

The huge area of continental shelf shapes life here.

It forms gentle, sloping beaches and the coast is dotted with islands.

Off the New South Wales coast sits a rather special place.

Cabbage Tree Island is the only island in the

entire region which remains covered in rainforest.

The tall, slender palms have given rise to an extraordinary

sea bird, evolved for this very specific habitat.

Beneath the forest canopy, the rocky slopes are littered with nooks and crannies.

And at the right time of year, a little ball of

fluff can invariably be found inside each one.

It is the world's only breeding colony of Gould's Petrel.

This chick is around three weeks old.

It's left alone while its parents are fishing at sea.

A spider poses no real threat.

But best not to take your chances when a spider's

fifteen centimetre leg span is wider than you are.

By nightfall, there's still no sign of mum or dad.

But then...

a somewhat undignified entrance.

But landing takes practice.

And it's a skill seldom used by petrels.

This species spends years at sea without touching dry land.

So walking over a rocky forest floor is an alien sensation.

To make matters trickier, almost every

available hole under a rock has a chick in it.

It's believed the adults use a keen sense of

smell to find their way back to their nest hole.

But it doesn't appear to be a fail-safe method.

Wrong hole.

Finally, after some searching, mum and chick are reunited.

It's a meal of regurgitated squid.

Over the next 12 weeks, night after night, crash landing after crash landing,

chicks all over this tiny island will wait for parents to return.

Until the one night when they won't come back.

Four months later, with only a tiny crown of fluffy down

left, the petrol chick has been abandoned by its parents.

It's been weeks since it's had anything to eat at all.

Hunger, desperation, and instinct need to sufficiently

combine before it has the will to make its move.

For those who don't, it holds no future.

The young bird decides it's time to leave the nest.

Sea birds, like petrels, rely on the wind to give them the lift needed for take-off.

But down here, beneath the forest canopy, the air is listless.

An ill-judged effort at flight could be its last.

Sharp palms and jagged rocks don't make for good crash mats.

If it's going to stand any chance of getting off the

island, it will need to get out from under the canopy.

But trees cover the whole island.

There's only one thing for it.

And webbed feet and wings are not ideal climbing equipment.

But the petrels here have evolved sharp

claws and a hooked beak to aid their ascent.

As the saying goes, if at first you don't succeed, you'll be deceived.

Attempting the climb again pushes the starving fledgling closer to exhaustion.

Panting, the fledgling wraps its wings around the trunk for a moment's respite,

using its tail feathers as a prop to rest.

Frantic wing flapping helps to propel the bird up the tree.

Having made it to the top, more obstacles lie in wait.

The thick stems at the center of the palm fronds are lined with sharp spikes.

Feathers are easily entangled.

Part fall, part flight, either way it's airborne.

And it won't touch land again for five or six years.

As the ghoul's petrels head off to a life far out at sea, other ocean wanderers are

being drawn to Australia's Pacific coastline.

Once a year, humpback whales pass Cabbage Tree Island on their journey north.

They have come to give birth to their young in the warm shallows.

The most famous of all is one of myth and legend.

Migaloo.

The albino humpback whale.

His name means white fella in aboriginal language.

His pale color is most likely due to a rare genetic mutation.

Believed to be 32 years old, Migaloo is in his prime.

And he knows how to demonstrate his power.

Scientists believe that tail slapping and rolling

is a form of communication between whales.

His companion applauds with a tail slap of its own.

First sighted in 1991, Migaloo was thought to be the only white whale in existence.

Since that time, newborn white calves have been spotted

in the Pacific around New Zealand and Australia.

It's thought that Migaloo may be the father of some of these pale youngsters.

Migaloo travels up and down the humpback highway.

As he makes the journey from Antarctica to the Great Barrier Reef.

And while the reef is famously home to some of the ocean's most colorful

characters, it's also home to some of the ocean's most endangered.

Ancient mariners such as the green sea turtle have

for thousands of generations returned here every year.

She has come back to lay her eggs in the very same place where her life began.

With flippers designed for sea and not sand, hauling her

200 kilo body up onto the shore is an enormous effort.

The expectant mother is able to carefully carve out a nest in the sand.

Her one and only act of parental care.

She deposits a clutch of around 100 eggs.

As she returns to the waves, more mothers clamber up the beach.

In fact, many, many more.

14,000 turtles could come ashore here in a single night.

In a single year, the turtles of Rain

Island could lay as many as 36 million eggs.

Two months later, the sand begins to stir.

A hatchling begins its frantic race to the water.

But by night, ghost crabs haunt this beach.

Flapping flippers are its only defense in a desperate attempt to get free.

Exhausted from its escape, it unwittingly walks

right into the arms of a waiting ghost crab.

But luck is on its side.

Running the gauntlet, the baby turtle makes it to the open ocean.

It's estimated that just about one in a thousand hatchlings survive to adulthood.

From here, the young turtles travel on currents circling Australia.

Some will swim further east into the South Pacific.

Others may travel north towards Asia.

The separation of the land between Asia and Australia

creates a passageway for tropical water to flow.

Because of this, it's the only continent

with warm water flowing south on both coasts.

Currents jettison into the Indian Ocean, and the rush of

tropical water spills south along the Western Australian shore.

This coastline is the world's most pristine.

An example of what marine ecosystems should look like.

Healthy, interconnected, teeming with life.

Thirty kilometres off the Kimberley coast lie the Pacific islands.

Eighteen thousand pairs of brown boobies nest here.

A new pair of boobies is hoping to start a family.

Their courtship is underway.

With a weedy offering, he attempts to woo her.

Perhaps another try.

No.

Surely his efforts have been sufficient.

But maybe not.

At the height of the breeding season, chicks of all sizes crowd the rocky shore.

As with humans, boobies approach parenting in a variety of styles.

Some respond to the nagging of the chicks immediately.

Others are less attentive.

Chicks born earlier in the season are taking part in beak skills lessons.

Becoming adept at flipping sticks and stones will

help with manipulating slippery fish mid-flight.

As the temperature rises to over forty degrees,

parents hover like a beach umbrella over their chicks.

Communication between this pair is on point.

They have the perfect tag team, taking domestic duties in turn,

allowing the other to go fishing.

Out at sea, the boobies move en masse.

They have spotted splashing in the distance.

A school of tuna and sharks have driven a bait ball of sardines to the surface.

Before long, frigate birds join the plunder.

Having got their fill, the birds head home to their hungry chicks.

Some frigate birds haven't bothered to head out to sea.

There's good reason these birds are known as the Pirates of the Skies.

Larger and faster than the boobies, they can bully

the smaller sea birds into giving up their lunch.

Outmaneuvered, it's forced to disgorge its food in mid-air.

Yet another chick will go hungry.

On shore, the chicks wait for a meal should finally be over.

The mates greet each other but lunch was stolen.

Now the onus of providing a meal falls to the other parent with added pressure.

Fortunately, it's the time of year when the westerly winds

strengthen the flow of currents fueling the plankton blooms.

The sudden bounty of food attracts many mouths.

Including the biggest fish of them all, the whale shark.

Despite their imposing size, they feed on microscopic plankton.

Chemicals released by the plankton are carried on the ocean current.

The whale sharks follow their sensitive noses

to find these blooms in the waters of Ningaloo.

With a large resident population of whale sharks in the area, scientists want to

understand how individuals are related to each other.

To do this, the scientist needs a sample of each whale shark's DNA.

And he's come up with a rather unusual way of doing this.

Remarkably, the giant animal will hang very calmly

in the water column whilst its nose is scratched.

Completely relaxed, the shark seems to enter a dream-like state.

Allowing the scientist to scrape tiny parasites off the shark's body.

These parasites, known as copepods, chew the shark's skin and drink their blood.

In return for the DNA sample, the whale sharks get rid of a few free-loaders.

Research has now shown that Australian whale sharks are the offspring of

ocean-wandering parents from as far away as Indonesia and Papua New Guinea.

Where they can be targeted by commercial fishermen.

Here in Ningaloo, the juvenile giants have a

precious sanctuary where they are protected species.

These gentle creatures prove not all sharks are ravenous meat-eaters.

But in Australian waters there are always other sharks who fit the stereotype.

Shark Bay in Western Australia and the water is as warm as a bath.

The faintest trace of blood in the water sends a signal.

While an entire whale carcass is like a siren

going off alerting sharks for miles around.

Tiger sharks.

Threatened globally but here it's a recently

discovered hotspot for these majestic predators.

A frail old whale having succumbed to its end becomes a banquet for the tigers.

These perfect predators have hunted the

world's oceans for more than 50 million years.

But they are not above a bit of scavenging.

The feeding frenzy has attracted tour boats.

The passengers are treated to ringside seats for the grizzly feast.

Such impressive schools of predators show that

Australia's ocean wilderness is still filled with life.

Predators are the ultimate expression of a healthy ocean.

But while scenes like this once dominated our planet today they are ever diminishing.

Such a rare and remarkable spectacle is also a

reminder of whose territory the ocean really is.

The abundance and diversity of Australia's ocean realm provides another opportunity

for the island nation to lead the world in marine

conservation at a time when global oceans are under threat.

Australian waters not only nurture unique species found nowhere else but also

provide protection to species from distant shores.

And because of this there is no underwater world more

worthy of safeguarding than here in the magical land of Oz.