Southern Seas Wild Down Under

Australia - the land of sun, sea

and surf.

Its golden shores are a magnet for beach-lovers and thrill-seekers.

Millions flock to explore the world's biggest coral reef.

But while the Great Barrier Reef and Sydney Harbour are the classic images of Australian life,

they're just the beginning.

Leave behind those playgrounds of the crowded east coast

and there's a much wilder party going on out there.

This continent has a coastline

that stretches from the hot northern tropics to the icy south.

And all around are seas with the most astonishing variety of life.

But these waters are challenging places to live.

Only the toughest survive.

Catching a wave is the easy bit.

The seas around Australia are as harsh as the land itself.

Only in very special places has marine life overcome the odds.

The Great Barrier Reef is the one everyone knows

but there's another coral extravaganza, on the other side of Australia.

Here, the land is a desert and it hardly ever rains.

There are no rivers flushing mud into the sea

so the water stays crystal clear.

It's perfect for growing corals,

and all a stone's throw from the beach.

Sandwiched between the desert shore and the open ocean,

Ningaloo Reef is 260km of coral oasis.

The outer reef wall encloses a self-contained world.

Life thrives

in the warmth of the sheltered lagoon.

When conditions are this good,

baby striped catfish gobble like mad to get a head start.

But until they've grown up,

they roll around the reef together.

This way, they look bigger and scarier than they would alone.

All the raw ingredients for life as a catfish -

or as anything else - are trapped within the lagoon.

..Until the autumn storms,

when the nutrition-packed reef water

spills out into the open sea.

For just a brief period,

the lifeless waters outside become a nourishing soup

and dinner guests arrive from out of the blue.

It's a whale shark.

These giant ocean cruisers make long treks

because food is so hard to find out in the clear tropical seas.

But they can be sure of getting a spot of lunch round here.

Ningaloo is the only place in the world

where you can see them feeding so close to shore.

Whale sharks aren't the only ones who've marked this event in their biological diary.

Vast shoals of sardines appear out of the Indian Ocean

to join Ningaloo's feast.

They're tailed by predatory dogtooth tuna.

Sharks appear - they're usually loners,

but they'll gang up for a party like this.

Sharks and tuna work the shoals, like dogs rounding up sheep,

till they've pinned them against the shore in one massive, tight slick.

The sardines look like easy meat,

but the slick is now a solid wall of fish -

it's hard for the predators to know where to start.

Every time the sharks plough in,

the little fish do their parting-the-waves trick.

It's a dazzling defence.

Tuna are like snipers - picking off fish from the edge of the huddle.

But it's hard for the sharks -

they can't get a grip on the vast, darting shoal.

The bait ball is squeezed tighter, and even the sharks can't miss.

Then, more heavyweight diners show up...

The sardine shoal is now virtually on the beach,

so surely out of reach of a huge Bryde's whale.

The sharks are finally making a dent in the shoal,

but it's nothing to what these monstrous whales can cram into their mouths.

When the food runs out,

the bounty hunters will drift away

and the sea around here will return to hard times.

Australia's north-west coast is pretty impoverished,

and little, fertile pockets like Ningaloo are rare.

But there ARE other surprises.

Further south, there's a giant inlet called Shark Bay.

It's surrounded by desert

and, under a blazing sun, sea water evaporates off quicker than a boiling billycan.

In the inner reaches of the bay,

the concentrated water is twice as salty as the sea -

and it doesn't get much tougher than that.

There's nothing in this brine for these jellyfish to eat,

so they've come up with a clever way to cope.

Their tissues contain millions of plant cells

that convert sunlight directly into food.

These jellies are solar-powered.

And since few predators

can cope with living in this salty world,

they're unhassled, and free to just soak up the sun.

The shape of the coast has created a natural harbour,

but on an Aussie scale.

Inside, is a place like no other.

Meadows of sea grass ripple over the sea bed.

These are the greatest underwater prairies on the planet.

Grass can tough it out anywhere, even in salty water.

In fact, here it's perfect -

the bay is calm, uniformly shallow, sunlit

and the sandy bottom is ideal for grass roots.

So it's sea grass all the way.

This lush, sunny grassland is the foundation of all life here.

There's plenty of food for sea horses...

..and hiding places for the small and inexperienced.

It's the tiny animals living around the stalks, as much as the grass itself,

that offer such a good living to so many types of fish.

Some look bizarre.

The moth fish may seem overdesigned in its armour plating,

but it has to be careful of enemies.

One bite from a venomous sea snake would be lethal.

But these are the real monsters of Shark Bay and they've spawned myths of giant proportions.

Once upon a time, people thought they were mermaids.

But it must have taken a desperate sailor to dream that one up!

They're actually dugongs, vegetarian sea mammals,

and there are over 10,000 of them in Shark Bay.

There might be even more,

if it weren't for the tiger sharks that give the bay its name.

Babies stick close to Mum.

They're sometimes called sea cows

because they graze for eight hours a day

and they need a huge gut to digest all that grass.

No wonder they look poorly.

Like all mammals, they have to take a breath from time to time.

DUGONG BLOWS AIR

..No worries in sea rarely deeper than 10m.

Thanks to the meadows of sea grass,

they lead a sheltered and stately life.

Without the unusual shape of the coast,

Shark Bay would be a sandy wasteland,

much like the desert that surrounds it.

Up north, there's another natural hot spot,

but forged from a very different set of conditions

Every year, Australia's top end is battered by the tropical monsoon.

THUNDER RUMBLES

AND WIND HOWLS

The weather is wild

and the currents are wicked.

The ocean is funnelled violently through a bottleneck,

the straits between Australia and the islands of Indonesia.

The resulting tidal bulge is the highest anywhere in the tropics

and it really stirs things up.

At low tide, the sea drops a massive 12m,

leaving the top end of Australia as one vast, steamy plain

of mud and mangrove.

The heavy monsoon rains have another vitalising effect -

they flush out rich silt from the rivers

and the coastal plains get a thick layer of mud.

BIRDS TWITTER

These muddy flats ooze with life

and it's all desperate for cover, now the tide's gone out.

And here's why.

But with only six hours of feeding time till the tide comes in,

mud skippers, golden ghost crabs and wading birds

have to start in top gear.

They're all desperate to get to the water's edge,

where the receding tide has exposed a slap-up feast.

A million migrating birds refuel

by sifting the warm silt for worms, snails and shellfish.

Some have travelled over 15,000km to feed here,

because these are the richest tidal mud flats in the world.

But, like a gold rush,

things can get lawless.

The sanderlings aren't above a bit of daylight robbery.

But the villains of the beach are the seagulls.

On an exposed mud flat,

it's impossible to keep your treasures to yourself.

This sand eel is quite a prize.

GULL SQUAWKS ANGRILY

There's no justice round here(!)

And, with the returning tide, the crab has no time

to make up for his loss.

While crabs can dig in under the racing tide,

waders have to cosy up at the top of the shrinking beach.

At high tide, the sea is brimming again and all you see is a desert shore.

But, in a few hours, the tide will recede,

the mud flats will be revealed

and the action will start all over again.

Northern Australia sits under the tropics.

Like a massive generator, it drives the climate of the land,

but it also has a powerful effect on Australia's seas.

The Leeuwin Current is a river of warm water from the north

that pumps down the west coast,

working its way into the cooler seas of the south.

It brings a lick of tropical warmth, but it doesn't bring any nutrients.

They've already been used up by other marine life.

This warm, empty current snakes into the Great Australian Bight,

the broad bay that arcs around Australia's southern side.

These coastal seas should be heaving with life,

as full of fish as the north Atlantic.

The cliffs should be screaming with nesting sea birds, but they're not.

The Leeuwin current drives a wedge of tepid water between the coast and the adjacent southern ocean.

As a result, the sea's as infertile as the land above.

Only extreme animals can live down here.

To find enough food, this Australian sea lion has just returned

from three days of long dives along the coast.

By any seal's standards, that's a marathon.

And so, on the last leg, she deserves an easy ride in.

SEA LION CALLS

She tells her pup she's back.

It's desperate for a feed.

They can only live here because of the unconventional way they bring up the pups.

These babies are huge. Other young seals would have been weaned by now,

but Australian sea lion pups suckle for over a year and a half,

way longer than their relatives.

A good, fat start is the only way to go

for a life in impoverished seas.

Even so, Aussie sea lions live for just 12 years.

It's the shortest lifespan of any seal.

When the mothers go back out to sea,

the pups make the most of their extended childhood.

ROARS

A coastal lagoon,

out of reach of predatory sharks,

is a safe place to try life in the water.

These Aussie sea lions depend on their mothers for years,

but they're not pampered - they have to prepare for life on the edge.

As adults, they make record-breaking dives, just to get enough to eat,

so they need this time to develop stamina, too.

But it looks as if they have a bit of fun along the way.

In these barren waters, it's hard for anything to make a living,

so what can possibly attract an animal the size of a whale?

She's come here to have a baby.

The warmth of the Leeuwin current

has created a lovely, whale-sized birthing pool.

Southern right whales spend most of the year in the subantarctic,

but the water's too cold and wild down there for a vulnerable baby.

They come to the protected bays

of the Australian Bight to rear their calves.

WHALE CALLS

But this is one hungry baby

and it needs mother's milk to build up its strength.

Breastfeeding is demanding -

the baby could suck its mother dry.

So what is SHE doing for food?

She sorted that out months ago,

by fattening up in the rich southern ocean.

Over the summer, she ate her way through two tons of krill a day.

It gave her enough energy to swim 2,000km,

give birth, produce thousands of litres of milk...

and then guide her calf back to the subantractic -

all without taking another bite.

WHALES CALL

Most animals, such as the giant cuttlefish,

don't venture such distances.

But they have to find food in these impoverished waters.

Their favourite prey is thin on the ground,

so they live and hunt alone.

First, they mesmerise their victim.

Then, they take aim.

It must be like looking down the barrel of a gun.

They're deadly accurate -

but not so hot in reverse.

Cuttlefish only get together in the autumn.

The Great Australian Bight has rocky reefs, which are vital in the breeding season,

and cuttles gather in their thousands to size each other up.

Giant cuttlefish are the biggest of their kind -

males can grow over a metre long

and they're the ones that command centre stage.

There's lots of showing off.

These flashy signals sort the men from the boys.

Holding ground is everything.

This big male wants to control a certain spot.

It's where the females will come to lay their eggs.

Other males try to muscle in.

These upstarts don't seem to be getting the message,

so the defending male throws his weight around a bit.

The females are much daintier,

but they always search for the biggest male - he usually holds the key to the best egg chamber.

After all the bravado,

he shows his tender side.

That's the romance out of the way.

Now it's back to guard duty.

Rivals never give up, and the big male wants to make sure

those are HIS babies under that rock.

To the east of here, life in the sea goes up a gear.

The warm Leeuwin current is running out of steam...

..and the cold southern ocean is beginning to take charge.

This force from the south has chiselled out huge limestone stacks.

The Twelve Apostles stand as if in reverence to the power of the sea.

Off the south-east of Australia,

these colder seas also start to shape life BENEATH the waves.

It's chilly, but it's paradise compared to the waters of the Bight.

It's as if the handbrake has finally been taken off

and life can really motor.

There are over 1,000 different types of kelp, alone.

Forests of giant kelp grow at top speed

in these ideal conditions.

The southern ocean pumps in all the basic ingredients.

With a good dose of sunlight,

and the plentiful nutrients you get in cool waters,

these seaweed trees can grow half a metre a day.

Sometimes, they reach 50 metres,

taller than most of the trees on land.

But it isn't just the luxuriant growth that makes this so special.

It's the remoteness.

It's been remote for so long,

that most of the plants and animals are found nowhere else on Earth.

Even by Australian standards,

this weedy sea dragon looks out of this world.

Like the kangaroos and koalas on land,

the sea animals have been caught up in their own evolutionary bubble.

Gliding through the seaweed, on its peculiar fins,

it proves that not all dragons are myths.

The curious little hand fish would rather walk than swim.

It uses ITS strange fins to stroll along the sea floor,

saving tail power for when it's really needed.

The leafy sea dragon has a dress code all its own.

It's modelled itself on the local seaweeds.

These dragons are nearly half a metre long,

but they easily go unnoticed.

This outrageous fashion statement is the perfect camouflage.

And these are not your typical Aussie males -

with sea dragons, it's the fathers that carry the eggs.

He makes quite sure that the offspring don't drift off.

It's crucial - they must hatch out and grow up against this same matching background.

They'd stick out like a sore thumb anywhere else,

so they're trapped forever in this corner of Australia.

Other residents are more cosmopolitan.

They're not so tied to this strange place.

In fact, some make every effort to get their offspring out of here.

And the ocean currents will help.

After sundown, a female lobster sets out across the reef.

Under her tail is a precious cargo of tiny larvae.

She's looking for the highest point on the reef,

to send them on their way.

The top spot is always the most popular,

but once all the females are in position, they wait.

There are fewer predators around in the hour before dawn,

so only then do they cast off their brood.

The water's more turbulent up here at the top of the reef,

so it's hard to hold her hands down.

With this odd and elegant way of giving birth,

lobsters have colonised the oceans.

The lucky ones get sucked into the powerful ocean current.

It only clips the corner of Australia,

so its effects largely pass the country by.

But it hits New Zealand square on,

so there, its impact is stronger.

New Zealand and Australia used to be joined together,

but they drifted apart millions of years ago,

and now their seas are very different.

The waters around New Zealand are topped up by nutrients

washed from this fertile land,

so they're richer and support more life.

Like this massive colony of gannets.

SQUAWKING

Each summer, 8,000 pairs will raise a family here.

And it's all based on the fabulous fisheries

of pilchards, anchovies and jack mackerel in the surrounding sea.

They have to pinpoint the catch,

but once they get their bearings, each hit is a bull's-eye.

Gannets slice into the water at 150 kilometres an hour,

which means they can score fish 10 metres below the surface.

If the fish go deeper,

the gannets just wait for the arrival of the back-up squad.

Common dolphins harass the sardines from below, pinning them up against the surface.

And that puts them back into gannet range.

Although these numbers are impressive, gannets are citizens of the world.

After all, you can see the same spectacle in British waters.

But New Zealand has been sitting out on its own for a very long time,

and it has some wildlife wonders that are truly unique.

Hector's dolphins are only found around the New Zealand coast.

They're also tiny -

at just over a metre long, they're the miniatures of the dolphin world.

They spend all their lives in the shallow water near the beach.

Further out, they'd be a mere snack for a shark or a killer whale.

But they don't need to go anywhere.

The bountiful Southern Ocean brings a total lifestyle package right to the door.

The huge swell is a reminder that New Zealand's southern tip

is in the firing line of the coldest, wildest ocean in the world.

It's one of the most fertile seas on Earth,

but sea birds can't breed out here - they need land.

The Snares Islands are the last specks of rock connected to the Australian continental shelf -

sure ground in the midst of a full-throttle ocean.

In the great sweep of open sea between Australia and Antarctica,

Snares crested penguins have no shortage of food.

It's dry land that's at a premium.

Every summer, the waters around these isolated islands swarm with penguins.

They're gathering to get the next generation under way.

The Snares Islands are the only rocks around where these birds can raise their young.

Twice a day, the adults must return to the nests to feed their chicks,

and they have to run the gauntlet of pirates.

50 metres out, the returning penguins raft together on the surface

until sheer numbers give them the confidence to make a dive for sure.

In the melee, head-ons can't be avoided.

Under the water, penguins are just too nippy for Hooker's sea lions.

This one's probably on the lookout for a weak or injured bird.

Fit penguins have no trouble covering the last stretch of open water.

Landing is trickier, but these birds are fearless.

Snares penguins have to be sure-footed -

their twice-daily commute includes a sheer wall of granite.

Penguins may not be the most elegant climbers,

but with their low centre of gravity, strong claws and sheer doggedness,

they get there in the end.

At the top, there's the rush-hour traffic and muddy forest trails to negotiate.

CHATTERING AND CHIRRUPING

Then they have to pinpoint the caws of their own out of the colonial din.

Only then can Mum and Dad bring home the bacon,

or in this case, regurgitated squid.

Two months and two tired parents later, the chicks are ready for the sea.

The journey begins enthusiastically as they all head for the water...

but it takes a while to find your feet.

Maybe it's better to give it just a few more minutes.

Snares penguins are just one of the many resilient animals

that have risen above the challenges in these southern seas.

These tough little birds have to overcome one more obstacle -

getting into the water's a triumph of substance over style.

Desert waters, tricky currents and sheer isolation

have all helped shape the diversity of marine life down under.

These are waters filled with surprises and delights

Hardship has simply brought out the best in the strange southern seas.

Next week, Wild Down Under takes you out bush

into Australia's strange and colourful gumtree country.

These spectacular woodlands are full of life

and home to Australia's weirdest and most charismatic animals.

From giant trees to miniature possums,

we travel the landscape that's the very essence of Australia.

Subtitles by Mairi Macleod & Alison Rae - BBC Broadcast 2003