Coasts Blue Planet II

An olive ridley turtle.

She's resting in the shallows off Costa Rica...

..having swum a thousand miles to be here.

All because the eggs she carries must be laid on dry land.

Now, she's returned to the very same beach

where she hatched ten years ago.

She must leave the safety of her marine world...

..and brave the alien world beyond.

She's heavily laden,

but the future of the next generation of her kind is at stake.

All along the beach, in a spectacle that has remained unchanged

for millions of years, mother sea turtles emerge from the ocean...

..in their hundreds of thousands.

Only those animals that overcome the great challenges of both land

and sea can make the most of life here on the coasts.

Our shores are places of sudden changes and rich rewards.

The Galapagos Islands in the tropical Pacific Ocean.

Their barren coastline looks unhospitable,

but one group of animals has learned to use it to their advantage.

Sea lions.

Bachelors.

They need to pile on the pounds, as only the biggest males

will attract a female and manage to breed.

If these young bulls fail to grow big enough,

they will remain exiled on this isolated shoreline.

So, one hungry young bull heads out alone.

He's on the hunt for big game.

Yellowfin tuna.

Each weighing 60kg...

..with a top speed of 40mph.

He can't possibly catch one in the open sea.

But he has a plan.

Ahead lies the entrance to the cove.

He herds them towards it...

..into his trap...

..driving them into a dead end.

But they give him the slip.

He's failed.

SEA LION BARKS

But there might be another way.

Now, they head off as a team...

..to round up more tuna...

..driving them back into the cove.

The sea lions fan out, channelling the tuna towards the bottleneck.

Once again, the tuna hit the dead end.

But this time,

the young bull doubles back to act as a blocker, sealing off the exit.

This time when the shoal tries to escape, he blocks them

and drives them back into the next blind alley.

The gang can now pick them off one by one.

This clever fishing technique, demanding foresight, planning

and cooperation, has only ever been seen here in the Galapagos.

Each massive fish provides them

with five times more protein than a normal day's hunting.

Finally, the young bull leaves his post...

..to claim his reward.

On a diet of protein-rich tuna,

he's well on the way to becoming a full-sized breeding bull.

By using this cove, these Galapagos sea lions have made the most

of the opportunities that occur where the coast's two worlds meet.

Coasts are the most swiftly changing of all ocean habitats

because of the tides.

Tides are created as the moon's gravity pulls at the sea.

As the moon circles our planet, the seas rise and fall,

typically twice a day,

creating the most constantly dynamic landscapes on Earth.

Nowhere else do sea-living creatures face such changeable conditions...

..with the daily risk of drying out and being scorched by the sun.

Where the tide retreats across a rocky shore,

it can leave behind a temporary oasis.

A rock pool.

Seemingly, it's a haven of calm.

But not for long.

Turning minutes into seconds reveals unexpected dramas.

In rock pools, grazers, scavengers and filter feeders

must all make the most of the few short hours before the tide returns.

Anemones gulp down anything they can reach...

..though some meals are harder to digest than others.

These magical worlds soon become battlegrounds.

A deadly predator with five arms

and, on the underside, a mouth.

The ochre starfish.

And it's in search of limpets.

For some, there is no escape. It engulfs them.

But other limpets have a secret defence.

They deploy a slippery shield...

..which allows them to slide to safety.

And this limpet has its own personal bodyguard.

A scale worm with a nasty nip.

The starfish prefers food that doesn't bite back.

The limpet carries on, its bodyguard tucked safe under its shell.

But there is one creature the limpets have no defence against.

A clingfish.

It has teeth that can lever under the shell

and twist the limpet off like a bottle top.

The clingfish then swallows it, shell and all.

Rock pool dramas like these

last just a few short hours before the tide returns.

Every day, the sea becomes land and the land becomes sea...

..bringing new opportunities.

A Sally Lightfoot crab.

One of thousands of shore crabs just waiting for their moment.

Every day, they gather on the tropical shores of Brazil...

..waiting for the tide to go out...

..which exposes their feeding grounds -

seaweed-covered rocks 100m from the shore.

Getting there is a race against the tide.

They leap from rock to rock.

These crabs seem to be afraid of the water.

And for good reason.

The moray eel.

The chain moray is a specialist crab hunter.

Its blunt teeth can easily grip and crush a crab's shell.

It's the crabs' deadliest enemy.

But the crabs' feeding grounds are still a long way off.

They must press on.

Halfway.

But their enemy has other ideas.

Crossing the land...

..to reset the ambush.

To feed, the crabs must keep going.

But nowhere is safe.

An octopus, also a crab killer.

The crabs make a dash for it.

Made it!

Risking life and limb to graze on these seaweed pastures.

But in two hours' time when the tide starts to turn,

they will have to run the gauntlet all over again.

Tides are not the only force to have an impact on the coasts.

The greatest waves originate far out to sea

and roll in towards the coast, growing as they come.

As the shallowing sea floor drags their underside,

their crests rise up to 100ft high, topple over and break.

Many of the biggest surfed waves in the world

are formed off Nazare in Portugal.

Every day along this coast, the impact of the waves

is equivalent to one and a half million tonnes of TNT.

Wave power gradually moulds and reshapes our coasts.

In some parts of Europe,

waves wear away as much as three metres of coastline each year.

The rate at which the waves reshape the rock depends on its hardness.

Where soft rock lies below hard, dramatic arches are carved.

It's an endless assault that gradually sculpts

vaulted cathedrals of stone, as here in northern Spain.

And wave power creates towering fortresses,

like these cliffs in the Arctic,

home to tens of thousands of breeding sea birds.

The faces of the cliffs are accessible only from the air

and have plenty of nooks and crannies

for those that can get there.

But to feed, sea birds must still master the ocean world beyond.

The puffin.

He's a fisherman and a father.

He has a mate for life.

Both share the burden of raising their week-old chick,

their puffling, who needs five square meals a day.

The parents alternate fishing trips.

It's Dad's turn.

When fish stocks are low, puffins must fly as much as 30 miles

out to sea to reach the good fishing grounds.

Once there, they plunge into another world.

Good fishing spots are hard to come by...and they have company.

Guillemots.

Like the puffin, their wings are short and good for diving.

Puffins can hold their breath for over a minute

and dive as deep as 40m.

A catch!

But it's a long way home.

After an exhausting round trip of almost 60 miles,

this puffin's nearly made it.

But there are pirates on this coast.

Arctic skuas.

All around, returning parents are being robbed.

The skuas' long, raked back wings

make them faster and more manoeuvrable.

Puffins must choose their moment wisely.

A near miss.

The last desperate burst of speed...

..and it's made it.

Safely home after a three-hour round trip...

..where his patient partner is waiting.

Today, their puffling will eat.

But where fish numbers are in decline,

many puffins now find it hard to get enough food for their chicks.

In the changing seas of today,

it can be even harder to be a successful puffin parent.

Overcoming the challenges of two worlds is seldom easy.

One marine creature has virtually abandoned the sea altogether.

On a few remote Pacific islands

lives the most terrestrial fish on the planet.

At the top of this metre-high limestone cliff...

..an eight-centimetre-long blenny has chosen a nest hole.

Up here, he can graze on the abundant algae

without any competition from seagoing fish.

The females are feeding beneath him.

He's keen to attract their attention.

But they are busy moisturising.

Staying damp is essential as they breathe through their skins.

To make himself conspicuous, he turns black...

..and flashes his orange fin.

He catches her eye.

But these Pacific leaping blennies seem afraid of the waves.

They're poor swimmers

and would be easy prey in the sea.

Time to try again.

She's tempted.

But, once again, distracted by a wave.

The male just won't give up.

Finally, she's hooked.

He makes way...

..so she can enter his cave.

And he encourages her to lay her eggs with his seductive dance.

He then fertilises them in the safety of his nest.

The blenny has given up the sea for a life on land.

Others have made an even more successful move,

but in a different direction.

Penguins have abandoned flying

and instead spend most of their lives swimming.

Their sleek survival suits of tightly packed feathers

are perfect for these freezing waters.

Yet they must still come ashore once a year.

South Georgia - an island wilderness close to Antarctica.

Each spring, its beaches become the busiest on Earth

as hundreds of thousands of king penguins return here.

They're heading for the colony.

But in their way lies the biggest wall of blubber on the planet.

Elephant seals.

It's the breeding season

and the four-tonne bulls are fighting

for control of their harems.

Best to wait for them to calm down.

He can't fly over this barrier

so he will have to walk as unobtrusively as possible...

..and hope that sleeping giants will continue to lie.

Careful!

This could be tricky.

A rival bull mounts a challenge.

The penguins could be caught in the crossfire.

Eight tonnes of blubber collide.

The towering beach master is victorious.

In the confusion, this penguin slips through.

Ahead are 40,000 chicks...

..hungry and overexcited.

But not every penguin has a chick to feed.

That's not why they're here.

There is another reason.

There is a trial of endurance that every penguin must face.

And it starts with a persistent itch.

His survival suit has been worn thin by months of swimming

in the rough Southern Ocean.

His solution is drastic.

Shed all four layers of feathers as quickly as possible.

The process is known as a catastrophic moult.

Until their feathers regrow,

penguins will remain rooted to the spot.

Having starved for a month, they're now fully waterproofed

and insulated once more...

..lean, hungry and eager to return to a life at sea.

Thanks to their waterproof plumage,

penguins are able to make the most of both worlds,

even in some of the harshest conditions on Earth.

The coasts of South Georgia are currently protected

by their remoteness.

Other coastlines are much more vulnerable.

And they are now changing faster than ever before.

Two-thirds of our major cities are on our coasts.

It's estimated that in the next decade,

we can expect 10% of the world's remaining wild shores

to be taken over by human development.

Yet every year, just off Florida's Palm Beach,

an extraordinary spectacle appears almost unnoticed.

The biggest gathering of coastal sharks on the planet.

Spinners and blacktips.

10,000 of them.

Every January, they seek out these warm shallows as a stopover

on their migration northwards.

Sharks have been gathering here since long before people arrived.

But today, they face levels of pollution

and habitat degradation as well as fishing pressures

that their ancestors would never have experienced.

It's no longer enough for coastal creatures

to master their own worlds.

Now, they must face the many challenges

that come from our world, too.

To film the most surprising coastal wildlife,

the Blue Planet II team travelled

to some of the remotest shores on the planet.

One destination was the Galapagos Islands.

Here, they were in search of an almost unbelievable story,

brought to them by a local cameraman, Richard Wollocombe.

Well, I was talking to a friend of mine

who's a fisherman over here and he said

that one day, he'd turned up here in this bay

and suddenly he saw a group of sea lions

chasing these massive tuna up onto the beach

and I was just like, "Yeah, funny one. I don't believe a word of that.

"That just sounds too unreal."

Still, the lure of the fisherman's tale was too great to ignore.

I'm a little nervous. If it doesn't happen, there goes my credibility.

The Blue Planet II team launch a full-scale expedition.

But one of them is still sceptical.

It's going to be pretty spectacular

if a sea lion could actually chase down and kill a tuna.

I'm still yet to be convinced.

They set up camp in this barren cove, home for the next month.

The local wildlife, famed for its tameness,

is curious to meet its new neighbours.

Shoo! Shoo!

Shoo, shoo, shoo!

Shoo, shoo!

With no sign of the sea lions,

the crew stake out the cove with remote underwater cameras.

Field assistant Roby Pepolas takes first watch.

This is the point of view where we try to see the sea lions coming,

jumping over the water.

If they are definitely coming very close, I say, "Action! Action!"

-Or, "Rock and roll!"

-HE LAUGHS

Three hours later...

Richard!

HE SHOUTS IN SPANISH

The aerial team are first up.

It's a sea lion chasing tuna into the bay.

Oh, he's got it! He's got it!

Unbelievable! Look at that, it's still struggling!

Holy Moley!

He's lost him.

The tuna gives the sea lion the slip.

Over the coming days, more sea lions arrive in the cove,

chasing in yellowfin tuna.

Yeah, yeah, yeah, yeah, yeah. Ooh!

Richard, there's more tuna and another sea lion.

There's, like, six tuna in the bay.

One sea lion has caught Richard's attention

and he has affectionately called him Tag Boy.

He's really different. He's, like, a prolific hunter. He's really agile.

It's just fascinating to watch

and see the picture emerge about who he is.

From above, the drone is revealing

how the group of sea lions are hunting together.

From the air, we really see the strategy of the sea lions

and see them with their individual roles as well.

Tag Boy stays off in the middle of the channel to make sure

none of them escape.

Everyone's got a role and they're really a team

in bringing them together.

Although the sea lions have been hunting in the shallows,

the crew are yet to see them drive a tuna onto the beach.

And to make matters worse, the sea lions aren't alone in this cove.

Galapagos sharks, each two metres long.

The shark almost beached itself

and stole the tuna from the big sea lion, who is now really angry.

Despite the sharks, to reveal the full story,

Richard needs to get in the water.

Classic shark attack scenario - blood in the water,

shallow and easy mistaken identity.

Watch your hands, Roby.

The crew gain

some protection from chainmail suits.

There's a lot of sharks. One, two, three, four, five, six sharks now.

With so much blood in the water, the sharks go into a feeding frenzy.

They make mincemeat of these tuna in seconds.

To be so close to something

so unbelievably ferocious and dangerous,

quite frankly, is amazing.

It's nice to be able to hide behind all this, though.

But then, after a week of increasing activity,

the sea lions suddenly stop fishing.

It's the first day that we haven't seen action during the whole day

since we start.

I kind of worry.

The tuna have disappeared.

Richard is worried.

The science is starting to show, across the globe,

that the seas are warming, they're becoming less productive.

Galapagos marine life relies on cold, deep currents

welling up intermittently to fertilise the surface waters.

If those upwellings become less consistent,

their lives could yet well be in jeopardy.

In the past,

when these cold water upwellings have temporarily stopped,

many sea lions have starved to death

and a warming ocean could further weaken these upwellings.

Then, after two weeks of nervous waiting, a hopeful sign -

a thick fog descends over the cove.

We've got very cold water that's come up, upwelled,

and spread across the ocean and mixed with the warm air,

creating the fog and we're hoping that this cold water

will just kick things off a bit and get the action going.

As the fog clears, a welcome sight.

The tuna are back with sea lions hot on their heels.

The crew leap into action.

HE SPEAKS IN SPANISH

Being in the water, Richard can at last follow the sea lions' teamwork.

And finally film Tag Boy beaching a tuna.

They know the bottlenecks in this labyrinth.

They know how to push them into those bottlenecks

and Tag Boy, almost his entire body was blocking the entrance,

and he was just gently back and forth, tiring the fish out.

Absolutely extraordinary, really, really impressive.

Director Rachel has a new-found respect for the sea lions.

I had no idea they were capable of this level of planning

and strategy and teamwork.

I had no idea they were this intelligent.

Richard has succeeded in filming this unique hunting strategy

and in doing so has proved the fisherman's tale to be true.

The sea lions' intelligence is unbelievably sophisticated

so to say that my expectations have been exceeded

is a slight understatement.

This has been one of the most remarkable times

I've ever had here in the Galapagos.

Next time, we travel the world

to uncover the biggest issues facing the ocean...

..meet the passionate people who've devoted their lives

to protecting it

and discover what the future holds for our Blue Planet.

To find out more about our oceans with this free poster, call...

..and follow the links to the Open University.