Ocean Deep Planet Earth

Away from all land.

The ocean.

It covers more than half the surface of our planet and yet, for the most part, it is beyond our reach.

Much of it is virtually empty,

a watery desert.

All life that is here is locked in a constant search to find food.

A struggle to conserve precious energy in the open ocean.

The biggest of all fish.

30 tonnes in weight, 12 metres long -

a whale shark.

Its huge bulk is sustained by near-microscopic creatures of the sea -

plankton.

Whale sharks cruise on regular, habitual routes between the best feeding grounds.

In February, that takes them to the surface waters far from the coast of Venezuela.

Others are already here.

Bait fish have come for the same reason - to feed on the plankton.

The whale shark has timed its arrival exactly right.

Oddly, the tiny fish swarm around it.

They're using it as a shield.

Other predatory fish are lurking nearby.

Yellowfin tuna.

They seem wary of the giant.

The shark dives, as if to escape from such overcrowding.

Now the tuna have a chance to attack the unprotected baitfish.

But then, back comes the giant.

It has taken a vast mouthful of the baitfish itself.

Plankton, it seems, is not the only food for a whale shark.

Both shark and tuna feast together.

But the tuna must beware.

Even they can end up in the whale shark's stomach.

Predators here must grab what they can, when they can, for such events do not last long.

The dense shoals on which so many depend, gather only when water conditions are perfect.

Many predators spend much of their time cruising the open ocean, endlessly searching.

Plankton-feeding rays do so, gliding with minimum effort.

The oceanic white tip shark.

Another energy-efficient traveller.

It specialises in locating prey in the emptiest areas of the open ocean,

patrolling the top 100 metres of water.

Taste in water is the equivalent of smell in the air.

An oceanic white tip is able to detect even the faintest trace.

Small pilot fish swim with it.

The shark can find prey far more easily than they can

and they'll be able to collect the scraps from its meals.

Its long fixed pectoral fins

enable it to soar through the water with the least expenditure of energy.

This shark has found a school of rainbow runners.

It would eat one, given the chance.

But rainbow runners are swift and agile and not easily caught.

So it bides its time.

There's a chance that, eventually, it may spot a weakened fish that's catchable.

The hunter,

endlessly waiting.

Excitement far from land.

A school of dolphin, 500-strong.

They've sensed there's food around and they're racing to catch up with it.

The news has spread - now a number of schools are on their way.

They're heading towards the Azores, volcanic islands 1,000 miles west of Portugal.

The dolphins scan the water ahead with their sonar.

They're close to their target.

CLICKING

This is it - scad mackerel.

It's difficult for a single dolphin to catch the fish.

To avoid wasting energy, they work as a group.

They drive the fish upwards, trapping them against the surface.

And there, other predators await them.

Corey shearwaters.

They're waiting for the dolphin to drive the prey closer to the surface.

Now the shearwaters can dive down on them, descending to twenty metres or more.

And the dolphins block the bait ball's retreat.

The dolphins leave as soon as they've had their fill.

And at last the mackerel sink below the diving range of the birds.

As the sun disappears, a profound change takes place in the ocean.

Deep-water plankton start to rise from the depths.

And another hungry army prepares to receive it.

Every night, wherever conditions are right,

countless millions of creatures from the deep migrate to the surface, seeking food.

A baby sailfish, 15 centimetres long, snaps up everything in its path.

In three years' time, it'll be one of the ocean's most formidable hunters weighing 60 kilos.

Just now, however, it's very vulnerable.

These manta rays are giants.

Eight metres across and weighing over two tonnes.

The blade-like projections on either side of the head help to steer plankton into the manta's mouth.

Dawn returns and the plankton sinks back into the depths.

If we are to follow, we must use a submarine.

As we descend into the darkness, the pressure builds, the temperature falls.

Below 500 metres, new mysterious animals appear.

Their bizarre shapes help them to remain suspended in the dark space.

Some resemble creatures familiar from shallower waters.

Others defy classification.

All around, organic particles drift downwards -

"marine snow", detritus from the creatures swarming in the sunlit waters above.

The snow is food for many animals here like the sea spider...

a small relative of shrimps and crabs.

Those strange leg-like appendages are feathered, to stop it from sinking.

They can also enmesh marine snow, which it wipes carefully into its jaws.

A sawtooth eel hangs upright and motionless.

Gazing ever upwards, it watches for prey silhouetted

against the faint glimmerings of light from the surface.

Days may pass before prey swims close enough for it to strike.

Farther down still, the blackness is complete.

No vestige of sunlight can penetrate as far as this.

Food is very scarce and nothing can afford to waste any energy.

A dumbo octopus simply flaps a fin.

No need for the jet propulsion used by its shallow-water relatives above.

The weirdest in this world of the strange - vampyroteuthis,

the "vampire squid from hell".

Disturb it, and it only retreats a little distance.

Go after it, and it has a special defence.

To see what it does, you must switch off the lights.

The vampire squid has lights of its own.

Bioluminescent bacteria shine from pockets on its arms, to confuse its predators.

Are those eyes?

In fact they're spots at the end of its mantle.

A bite there would leave the head unscathed.

The threat diminishes

and vampyroteuthis disappears into the blackness.

At last, the sea floor.

Over two miles down.

The pressure here is 300 times that at the surface.

It takes several months for marine snow to drift down as far as this.

As you travel away from the rocky margins of the continents, an immense plain stretches ahead.

It extends for thousands of miles,

gradually sinking downwards.

There are faint trails in the ooze...

signs that even here, there is life.

These are what made some of them.

Sea urchins sifting the accumulating drifts.

Shrimps, standing on elegant tip-toe, fastidiously select the particles that appeal to them.

But in the deep sea, as everywhere else, if there are grazers, there are hunters.

A monkfish.

Almost indistinguishable from the sand on which it lies.

Why waste energy chasing around, if you can attract prey towards you with a lure?

Maybe that one was a bit big.

The monkfish can wait - for days if necessary - until the right-sized meal turns up.

Scavengers, on the other hand, have to move around to find their food.

Crabs can detect the faintest of tastes in the water

and that helps them locate the latest body to drift down from above.

Eels are already feeding on the corpse.

Isopods, like giant marine woodlice a third of a metre long,

are ripping into the rotting flesh.

Over the next few hours, there'll be frenzied competition

between scavengers of all kinds to grab a share.

Just occasionally there is a gigantic bonanza.

The remains of a sperm whale.

It died five months or so ago.

There's little left but fatty blubber clinging to its bones.

Its flesh has nourished life for miles around, but now the feast is almost over.

Spider crabs a metre across still pick at the last putrid remains.

A few weeks more, and nothing will be left but bare bones.

The crabs will have to fast until the next carcass drifts down.

But not all food comes from the sunlit world above.

The floor of the Atlantic Ocean is split in two by an immense volcanic mountain chain

that winds unbroken for 45,000 miles around the globe.

In places, it's riven by great fissures from which superheated water

loaded with dissolved minerals, blasts into the icy depths.

Clouds of sulphides solidify into towering chimneys

as tall as a three-storey house.

At 400 degrees, this scalding cocktail of chemicals

would be lethally toxic to most forms of life.

But astoundingly, a particular kind of bacteria thrives here.

And feeding on the bacteria, vast numbers of shrimps.

So, beyond the farthest reach of the sun's power,

a rich, independent community exists

that draws all its energy directly from the earth's molten core.

On the other side of the planet, in the western Pacific bordering Japan,

the Dragon Chimneys.

Another series of hot vents erupting in the darkness.

Here, more but different bacteria thrive in a similar way.

And here, too, more crustaceans,

quite different species from those around the hot vents in the Atlantic.

These are squat lobsters, clad in furry armour,

jostling with one another beside the jets of superheated water

for the best places from which to graze on bacteria.

These vents too, like those in the Atlantic, are isolated oases,

so widely separated that each community is unique.

Cross to the other side of the Pacific,

to the deep near the Galapagos Islands,

and there are yet other fissures venting superheated water.

One and a half miles down, at a site known as Nine North,

towering chimneys support a spectacular display of giant tube-worms.

These vents give off so much energy

that some of the worms reach three metres in length.

They're the fastest-growing marine invertebrates known.

All told, over 50 different species have so far been found living here.

The inhabitants of these bustling communities may grow at speed,

but their existence can also be short,

for the vents do not erupt indefinitely.

Suddenly, unpredictably, they may become inactive.

Nine months have passed at Nine North.

What were only recently chimneys teeming with life

have turned into cold, sterile mineral monuments.

Some eddy, deep in the earth's crust, diverted the volcanic energy elsewhere

and an entire micro-world was extinguished.

In places, volcanoes have erupted to build great submarine mountains.

There are thought to be around 30,000 such volcanoes -

some, measured from the sea floor, are taller than Everest.

Sheer cliffs soaring to drowned volcanic peaks.

Powerful currents sweep up the mountain's flanks,

transporting nutrients from deep water towards the summits.

The hard rock provides excellent anchorage

for communities of great variety and stunning colour.

Soft corals, several metres across, collect the "marine snow"

as it drifts past.

Whip corals stretch out into the current.

Giant sponges filter nourishment from the cold water.

A richly varied community flourishes here, sustained by the nutrients

and detritus in the icy currents that flow around the peak.

Yet it is all blossoming on an extinct volcano

a mile below the reach of the sun.

A nautilus. It spends its days hiding 400 metres down,

but as night falls, it ascends up to the reefs to look for food.

Its graceful shell contains gas-filled flotation chambers

that control its depth.

It's powered by a jet of water squirting from a siphon.

But it travels shell-first so it can't see exactly where it's going.

Its nearest living relatives are squid and octopus

which, over evolutionary time, have both lost their shells.

And the octopus has become one of the nautilus's major predators.

It's a master of disguise.

The nautilus keeps well clear of them.

Its small tentacles carry highly developed chemical sensors

which can detect traces of both predators and prey.

It uses its water jet to dig in the sand.

Because it devotes so little energy to swimming,

it only needs a meal once a month.

Got something.

And just as well.

Dawn is approaching and it has to puff its way back to deeper waters.

30 miles away, shoals of squid are jetting upwards towards the surface.

By night, they seek small fish among the plankton, but they're cautious.

ANIMALS SQUEAK

Pacific spotted dolphin.

They're guided by their sonar.

THEY SQUEAK

The dolphin, as so often are working as a team,

synchronising their attacks to confuse their prey.

THEY SQUEAK

As dawn approaches, squid and fish and plankton retreat downwards

to shelter in the darkness.

Some of these isolated volcanoes rise

as much as 9,000 metres from the sea floor, reaching close to the surface.

Around these peaks, invigorated by daily sunshine,

marine life flourishes in spectacular abundance.

Fish crowd here because the volcano forces nutrients to the surface,

encouraging the plankton to bloom.

An oceanic wanderer, a mola mola, stops by

to be cleaned by reef fish at the seamount edge.

Butterfly fish pluck string-like parasites from its flanks.

The huge fish lives on jellyfish over 1,000 metres down

where the water is 20 degrees colder.

So a brush-up near the surface allows it to warm up

before making more deep-water forays.

The summit of this volcanic mountain rises above the surface of the sea.

It's Ascension Island,

800 miles from any other land,

a welcome, vital haven for long-distance travellers.

Frigate birds spend months continuously airborne at sea.

But at nesting time, they come to Ascension from all over the ocean.

The island's barren slopes of volcanic ash and lava

might seem to offer perfectly good sites for a nest.

But the frigates choose an even more isolated site -

Boatswainbird Island, a lonely pillar just off Ascension's coast.

Frigates are the world's lightest bird relative to their wingspan

and they can soar for weeks on end with minimal effort.

They seem much more at home in the skies

than in a crowded colony on land, but nest they must.

They come from all over the Atlantic to this, their only colony.

There are boobies here too.

To raise their young, seabirds worldwide seek such remote islands.

Swimmers also come to Ascension to breed.

A female green turtle approaches the coast.

She's not eaten once in two months.

She may have travelled 1,000 miles from her feeding grounds -

the greatest journey of her kind.

Many others are here too, resting on the sandy sea floor,

awaiting the darkness of night when it'll be safer to visit the beaches.

Eggs that were laid a few weeks ago at the start of the season

are beginning to hatch.

Most hatchings happen at night.

Now in the light of day, the young are extremely vulnerable.

They must get to the sea as soon as possible.

But their trials have only just begun.

Many will drown in the pounding waves.

During the next 20 years, the vast majority will inevitably die.

Those that survive will eventually, as their mothers did before them,

return to the very same beach where they were hatched.

How they find their way back across thousands of miles of open ocean,

we still have no idea.

A frigate soars.

Somewhere beneath the surface below, there is the food it must have.

But where?

Those that fly above the ocean

must be able to read the signs of fresh supplies or perish.

100 miles from the Mexican coast, and keen eyes have spotted movement.

Sailfish, three metres long, are closing in on prey.

They will only use just enough energy to make their kill,

never wasting a fin stroke.

Nearly 100 sailfish have surrounded a single school of baitfish.

It's very rare to see so many of these hunters in one place.

To herd their prey, the predators raise their huge dorsal fins.

A mistimed strike by one sailfish could fatally damage another.

But each continually changes its colour,

from blue, to striped, to black.

That warns its companions of its intentions

and also confuses the prey.

As the shoal is driven nearer the surface,

it comes within the range of the seabirds.

Out here in the open ocean, there is nowhere for the baitfish to hide.

Sailfish live a high-octane life.

To survive, they must find prey daily

so their entire existence will be spent on the move.

Over 90% of the living space for life on our planet is in the oceans.

Home to the biggest animal that exists or has ever existed.

The blue whale.

Some weigh nearly 200 tonnes,

twice the size of the largest dinosaur.

Despite their great size, we still have little idea of where they travel

in the vast oceans and none at all of where they go to breed.

The largest animal on Earth feeds almost exclusively

on one of the smallest - krill, shrimp-like crustaceans.

They take many tons of water into their ballooning throats

in a single gulp and sieve out what it contains.

Every day, each one swallows some four million krill.

Such gargantuan harvests depend on the continuing fertility

of the oceans.

But global changes now threaten the great blooms of plankton

on which the whales depend.

Once - and not so long ago - 300,000 blue whales roamed the oceans.

Now less than 3% of that number remains.

Our planet is still full of wonders.

As we explore them, so we gain not only understanding, but power.

It's not just the future of the whale that today lies in our hands,

but the survival of the natural world in all parts of the living planet.

We can now destroy or we can cherish.

The choice is ours.

For the Planet Earth team, just finding their subjects

in the vast, empty spaces of the open ocean was often difficult enough.

But one of their greatest challenges was to find the increasingly rare

oceanic white tip shark and film this fearsome predator

in blue water without the safety of a shark cage.

The Bahamas in winter,

and the underwater team prepares to film rare close-up images

of oceanic white tips in their natural surroundings.

Cameraman Rick Rosenthal has been working in the open ocean

for over 30 years and has filmed these sharks before.

It came up, roaring right up to the Zodiac and I was...

the mouth was full open.

To help him, he's trusting his life to the latest in wetsuit camouflage.

The new Rick Rosenthal,

I'm going the pelagic jellyfish look, to kind of get lost in the big world out there.

Whatever we can do to get an edge,

anything to get close to the animals.

Also on board is cameraman Doug Anderson.

He's never encountered an oceanic white tip before,

but he does have a view on what they'll be like.

I roughly think of them like little dogs,

and some little dogs are nice little dogs and some little dogs are nasty little dogs.

Whatever - when you're in the water, you have to make your presence felt

and try and judge the situation to the best of your ability.

Unlike the more familiar reef sharks,

oceanic white tips are true ocean wanderers.

Once they were abundant, but fishing for shark fins

has devastated their numbers, making them far more difficult to find.

As they prepared to dive, they had no way of knowing what lay in wait below.

It was soon clear that regardless of being nice or nasty,

Doug's "little dogs" were also somewhat camera-shy.

Nothing.

Fishless.

As with most dives in the open ocean, seeing nothing is normal,

so Rick and Doug persisted in their search.

Reef sharks and nurse sharks.

-Oh.

-You OK?

One big old shark hanging down there, deep.

Just deep, deep, deep, wouldn't come up.

May have to reconsider other ways of getting these,

these little oceanics to, to pose for us.

With the sharks refusing to appear, the team was forced to resort to

the tried and tested technique of chumming -

it was time to give the "little dogs" a bone.

All we've done is set up a chum line which is a case of hanging an onion bag

full of the most disgusting offal that you can think of,

stuff that they couldn't even face putting into Turkey Twizzlers.

And we're waiting for some sharks to turn up, there's really not much science in it

apart from making sure that the slick of smell and stuff

that's gonna attract the sharks goes in the right direction.

And the right direction for here is, is not over the reef

but over the blue water where the oceanics live.

The irresistible smell of rotting fish worked its magic

and soon the first shark appeared.

There was no knowing how long it would hang around...

so the divers needed to get into the water fast.

The team could at last get to work.

-To your right!

-Right behind you!

-Shark!

The oceanic white tip is a known man-eater,

a reputation it gained from attacking sailors forced to abandon ship

during the Second World War.

Yet this shark seemed almost nervous,

wary of the two strange objects that had entered its world.

This was Doug's first chance to get a good look at his "little dog".

Amazing.

Totally amazing.

Goddamn doubting Thomas - think we were out here screwin' around?

So beautiful, I mean...

just...real, oceanic wanderers, those big pectorals.

-Right there, see him?

-On the next dive the smell of chum attracted two sharks looking for an easy meal.

How did Rick feel about getting in with them?

Is it a smart idea to stick fish guts and chum and when you put a diver in? Hell, no!

Cos we become part of the chum.

Diving with known man-eaters is potentially dangerous,

especially when they arrive expecting food.

The secret to staying safe is to watch their every move

and to know when to leave the water.

These sharks appear relaxed, allowing Rick and Doug to get rare pictures

of one of the ocean's top predators.

But white tips are very unpredictable.

So while the sharks were being nice, the team took full advantage

to get some of the close-up shots they needed.

But they were always looking for tell-tale signs

that things were about to get nasty

and if in doubt, there was only one option.

Oh.

That was exciting.

The final day saw the arrival of three sharks.

Wow, he's huge!

Look at the size of him.

This is kinda crazy out here now.

Now, the team began to notice a change.

The white tips were becoming bolder and more aggressive.

Their courage seemed to be buoyed by the presence of the other sharks.

Worse, it was becoming impossible to keep track of three sharks at once

and soon the white tips began to show more than just curiosity

towards the divers.

Some sharks investigate potential prey

by "bumping" it before they attack.

Rick recognised the signs.

It was time to leave.

He was surrounded and knew the boat had to get to him fast.

That was too intense.

The one took, one had my fin it was...

One had my fin, it would hit me,

I was filming one, the other would just, "Oh, excuse me."

It was down to Doug to get the final shots

and get out before his "nice little dogs" turned really nasty.

That's enough for me.

I'm getting out when the getting's good!

That shark's getting very electric and hot.

I tell you, he's got a mouth like that, that can take your leg off.

Fabulous animal but it's into its feeding mode now

and wants to eat and I don't wanna be part of it.

For Doug, there was always just one more shot to get.

But concentrating on what was in front of him meant he couldn't see

what was creeping up behind.

And when one of the cruising sharks changed to attack speed...

it was definitely time to get out and join Rick in the safety of the boat

before it was too late.

That was very exciting - it was great.

They seemed a lot more interested than Rick, I think it's his suit.

Let's go find a bottle of rum, huh?

The oceanic white tips had allowed the Planet Earth team

a rare insight into their world.

Now it was time to leave these magnificent animals in peace.

Subtitles by Red Bee Media Ltd

Email [email protected]