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Away from all land...
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the ocean.
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It covers more than half the surface of our planet
and yet, for the most part,
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it is beyond our reach.
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Much of it is virtually empty, a watery desert.
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All life that is here
is locked in a constant search to find food.
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A struggle to conserve precious energy
in the open ocean.
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The biggest of all fish.
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30 tons in weight, 12 metres long,
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a whale shark.
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Its huge bulk is sustained
by near microscopic creatures of the sea,
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plankton.
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00:01:52,440 --> 00:01:56,750
Whale sharks cruise on regular, habitual routes
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between the best feeding grounds.
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00:02:03,680 --> 00:02:09,870
In February, that takes them to the surface waters
far from the coast of Venezuela.
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Others are already here.
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Bait fish have come for the same reason,
to feed on the plankton.
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The whale shark has timed its arrival exactly right.
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Oddly, the tiny fish swarm around it.
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They're using it as a shield.
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Other predatory fish are lurking nearby.
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Yellowfin tuna, they seem wary of the giant.
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The shark dives,
as if to escape from such overcrowding.
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Now the tuna have a chance to attack
the unprotected bait fish.
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But then back comes the giant!
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It has taken a vast mouthful of the bait fish itself.
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Plankton, it seems,
is not the only food for a whale shark.
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Both shark and tuna feast together.
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But the tuna must beware.
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Even they can end up
in the whale shark's stomach.
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Predators here must grab what they can,
when they can,
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for such events do not last long.
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The dense shoals on which so many depend
gather only when water conditions are perfect.
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00:05:06,640 --> 00:05:12,870
Many predators spend much of their time
cruising the open ocean, endlessly searching.
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00:05:18,080 --> 00:05:23,150
Plankton-feeding rays do so,
gliding with minimum effort.
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00:05:37,520 --> 00:05:40,190
The Oceanic whitetip shark,
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another energy-efficient traveller.
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It specialises in locating prey
in the emptiest areas of the open ocean,
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patrolling the top 100 metres of water.
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00:06:05,280 --> 00:06:10,070
Taste in water is the equivalent of smell in the air.
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00:06:10,160 --> 00:06:14,990
An Oceanic whitetip is able to detect
even the faintest trace.
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Small pilot fish swim with it.
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The shark can find prey
far more easily than they can
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and they'll be able to collect the scraps
from its meals.
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Its long, fixed pectoral fins
enable it to soar through the water
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with the least expenditure of energy.
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This shark has found a school of rainbow runners.
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It would eat one, given the chance.
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But rainbow runners are swift and agile
and not easily caught.
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00:07:01,400 --> 00:07:04,190
So, it bides its time.
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00:07:04,320 --> 00:07:09,750
There's a chance that, eventually,
it may spot a weakened fish that's catchable.
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The hunter, endlessly waiting.
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Excitement far from land.
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A school of dolphin, 500 strong!
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They've sensed there's food around
and they're racing to catch up with it.
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00:08:10,760 --> 00:08:16,030
The news has spread.
Now a number of schools are on their way.
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They're heading towards the Azores,
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volcanic islands 1, 000 miles west of Portugal.
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The dolphins scan the water ahead
with their sonar. They're close to their target.
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This is it, scad mackerel.
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It's difficult for a single dolphin to catch the fish.
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To avoid wasting energy, they work as a group.
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They drive the fish upwards,
trapping them against the surface.
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And there, other predators await them.
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Cory shearwaters.
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They're waiting for the dolphin
to drive the prey closer to the surface.
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00:09:52,440 --> 00:09:58,070
Now the shearwaters can dive down on them,
descending to 20 metres or more.
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00:10:02,520 --> 00:10:06,070
And the dolphins block the bait ball's retreat.
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00:10:36,200 --> 00:10:40,270
The dolphins leave
as soon as they've had their fill.
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00:10:44,560 --> 00:10:49,910
And, at last, the mackerel sink below
the diving range of the birds.
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00:11:13,280 --> 00:11:18,470
As the sun disappears,
a profound change takes place in the ocean.
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00:11:20,080 --> 00:11:23,630
Deepwater plankton start to rise from the depths
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00:11:23,720 --> 00:11:28,550
and another hungry army prepares to receive it.
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00:11:52,040 --> 00:11:57,990
Every night, wherever conditions are right,
countless millions of creatures from the deep
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migrate to the surface seeking food.
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00:12:10,360 --> 00:12:16,430
A baby sailfish, 15 centimetres long,
snaps up everything in its path.
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In three years' time, it will be one of the ocean's
most formidable hunters, weighing 60 kilos.
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00:12:25,280 --> 00:12:28,990
Just now, however, it's very vulnerable.
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These manta rays are giants.
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00:13:13,640 --> 00:13:17,630
Eight metres across and weighing over two tons.
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00:13:21,200 --> 00:13:24,270
The blade-like projections
on either side of the head
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help to steer plankton into the manta's mouth.
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Dawn returns
and the plankton sinks back into the depths.
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If we are to follow, we must use a submarine.
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00:14:01,440 --> 00:14:07,590
As we descend into the darkness,
the pressure builds, the temperature falls.
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00:14:11,560 --> 00:14:15,830
Below 500 metres,
new mysterious animals appear.
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00:14:21,640 --> 00:14:27,750
Their bizarre shapes help them
to remain suspended in the dark space.
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00:14:31,000 --> 00:14:35,230
Some resemble creatures
familiar from shallower waters.
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00:14:43,440 --> 00:14:46,590
Others defy classification.
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All around, organic particles drift downwards.
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00:14:58,720 --> 00:15:04,830
Marine snow, detritus from the creatures
swarming in the sunlit waters above.
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00:15:07,280 --> 00:15:10,350
The snow is food for many animals here,
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like the sea spider,
a small relative of shrimps and crabs.
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00:15:27,240 --> 00:15:33,590
Those strange leg-like appendages
are feathered to stop it from sinking.
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00:15:35,600 --> 00:15:42,390
They can also enmesh marine snow,
which it wipes carefully into its jaws.
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00:15:57,880 --> 00:16:02,670
A sawtooth eel hangs upright and motionless.
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00:16:05,840 --> 00:16:07,390
Gazing ever upwards,
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it watches for prey silhouetted against
the faint glimmerings of light from the surface.
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00:16:19,640 --> 00:16:25,310
Days may pass before prey swims
close enough for it to strike.
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00:16:30,400 --> 00:16:34,030
Farther down still, the blackness is complete.
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00:16:35,000 --> 00:16:39,830
No vestige of sunlight can penetrate as far as this.
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00:16:43,200 --> 00:16:48,870
Food is very scarce
and nothing can afford to waste any energy.
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A dumbo octopus simply flaps a fin.
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No need for the jet propulsion
used by its shallow water relatives above.
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The weirdest in this world of the strange,
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Vampyroteuthis, the vampire squid from hell.
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Disturb it and it only retreats a little distance.
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Go after it and it has a special defence.
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To see what it does,
you must switch off the lights.
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The vampire squid has lights of its own.
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Bioluminescent bacteria shine
from pockets on its arms to confuse its predators.
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Are those eyes?
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In fact, they're spots at the end of its mantle.
A bite there would leave the head unscathed.
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The threat diminishes and Vampyroteuthis
disappears into the blackness.
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00:18:57,960 --> 00:19:00,590
At last, the sea floor.
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00:19:00,680 --> 00:19:03,350
Over two miles down,
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the pressure here is 300 times that at the surface.
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00:19:08,440 --> 00:19:13,990
It takes several months for marine snow
to drift down as far as this.
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00:19:18,440 --> 00:19:22,390
As you travel away from the rocky margins
of the continents,
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an immense plain stretches ahead.
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00:19:28,600 --> 00:19:33,950
It extends for thousands of miles,
gradually sinking downwards.
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00:19:41,040 --> 00:19:47,390
There are faint trails in the ooze,
signs that even here, there is life.
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These are what made some of them.
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00:19:57,800 --> 00:20:02,230
Sea urchins sifting the accumulating drifts.
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00:20:06,600 --> 00:20:13,190
Shrimps, standing on elegant tiptoe, fastidiously
select the particles that appeal to them.
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00:20:21,320 --> 00:20:28,110
But in the deep sea, as everywhere else,
if there are grazers, there are hunters.
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00:20:37,480 --> 00:20:43,110
A monkfish, almost indistinguishable
from the sand on which it lies.
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Why waste energy chasing around
if you can attract prey towards you with a lure?
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Maybe that one was a bit big.
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00:21:18,040 --> 00:21:21,550
The monkfish can wait for days, if necessary,
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until the right-sized meal turns up.
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00:21:28,280 --> 00:21:33,510
Scavengers, on the other hand,
have to move around to find their food.
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Crabs can detect the faintest of tastes
in the water and that helps them locate
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the latest body to drift down from above.
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00:21:45,840 --> 00:21:49,190
Eels are already feeding on the corpse.
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00:21:55,880 --> 00:22:00,430
Isopods, like giant marine woodlice
a third of a metre long,
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are ripping into the rotting flesh.
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00:22:04,280 --> 00:22:07,670
Over the next few hours,
there'll be frenzied competition
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between scavengers of all kinds to grab a share.
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Just occasionally, there is a gigantic bonanza.
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The remains of a sperm whale.
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00:22:57,440 --> 00:23:00,550
It died five months or so ago.
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There is little left but fatty blubber
clinging to its bones.
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00:23:08,040 --> 00:23:14,070
Its flesh has nourished life for miles around,
but now, the feast is almost over.
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00:23:19,320 --> 00:23:25,190
Spider crabs, a metre across,
still pick at the last putrid remains.
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00:23:32,880 --> 00:23:37,990
A few weeks more
and nothing will be left but bare bones.
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00:23:38,800 --> 00:23:43,830
The crabs will have to fast
until the next carcass drifts down.
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00:23:50,440 --> 00:23:54,750
But not all food comes
from the sunlit world above.
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00:23:56,040 --> 00:24:02,550
The floor of the Atlantic Ocean is split in two
by an immense volcanic mountain chain
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that winds unbroken for 45, 000 miles
around the globe.
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In places it's riven by great fissures
from which superheated water,
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loaded with dissolved minerals,
blasts into the icy depths.
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00:24:33,200 --> 00:24:39,950
Clouds of sulphides solidify into
towering chimneys as tall as a three-storey house.
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At 400 degrees, this scalding cocktail of chemicals
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would be lethally toxic to most forms of life.
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But, astoundingly, a particular kind of bacteria
thrives here.
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00:24:59,840 --> 00:25:04,510
And feeding on the bacteria,
vast numbers of shrimps.
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00:25:14,520 --> 00:25:18,030
So, beyond the farthest reach of the sun's power,
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a rich independent community exists
that draws all its energy
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directly from the earth's molten core.
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On the other side of the planet,
in the western Pacific bordering Japan,
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the dragon chimneys.
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Another series
of hot vents erupting in the darkness.
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Here, more, but different, bacteria
thrive in a similar way.
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And here, too, more crustaceans,
but quite different species
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from those around the hot vents in the Atlantic.
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These are squat lobsters clad in furry armour,
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jostling with one another
beside the jets of superheated water
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for the best places
from which to graze on bacteria.
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These vents, too, like those in the Atlantic,
are isolated oases,
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so widely separated,
that each community is unique.
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Cross to the other side of the Pacific,
to the deep near the Galapagos Islands,
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and there are yet other fissures
venting superheated water.
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One and a half miles down,
at a site known as Nine North,
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towering chimneys support a spectacular display
of giant tubeworms.
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These vents give off so much energy that
some of the worms reach three metres in length.
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They're the fastest-growing
marine invertebrates known.
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All told, over 50 different species
have so far been found living here.
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The inhabitants of these bustling communities
may grow at speed,
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but their existence can also be short,
for the vents do not erupt indefinitely.
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00:28:14,400 --> 00:28:18,070
Suddenly, unpredictably,
they may become inactive.
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00:28:23,320 --> 00:28:26,990
Nine months have passed at Nine North.
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00:28:27,080 --> 00:28:30,550
What were only recently
chimneys teeming with life
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have turned into cold, sterile, mineral monuments.
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Some eddy, deep in the earth's crust,
diverted the volcanic energy elsewhere
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and an entire micro-world was extinguished.
187
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In places, volcanoes have erupted
to build great submarine mountains.
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00:29:04,120 --> 00:29:08,510
There are thought to be
around 30, 000 such volcanoes.
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00:29:08,600 --> 00:29:13,830
Some measured from the sea floor
are taller than Everest.
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Sheer cliffs soaring to drowned volcanic peaks.
191
00:29:35,920 --> 00:29:39,270
Powerful currents sweep up the mountain's flanks,
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transporting nutrients from deep water
towards the summits.
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The hard rock provides excellent anchorage
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for communities of great variety
and stunning colour.
195
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Soft corals, several metres across,
collect the marine snow as it drifts past.
196
00:30:05,920 --> 00:30:09,390
Whip corals stretch out into the current.
197
00:30:12,000 --> 00:30:16,350
Giant sponges filter nourishment
from the cold water.
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00:30:30,960 --> 00:30:34,150
A richly varied community flourishes here,
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sustained by the nutrients and detritus
in the icy currents that flow around the peak.
200
00:30:45,800 --> 00:30:52,510
Yet, it is all blossoming on an extinct volcano
a mile below the reach of the sun.
201
00:31:17,800 --> 00:31:22,630
A nautilus.
It spends its days hiding 400 metres down,
202
00:31:22,720 --> 00:31:27,270
but as night falls,
it ascends up to the reefs to look for food.
203
00:31:33,120 --> 00:31:39,430
Its graceful shell contains gas-filled
floatation chambers that control its depth.
204
00:31:42,520 --> 00:31:46,590
It's powered by a jet of water
squirting from a siphon.
205
00:31:49,240 --> 00:31:54,630
But it travels shell-first,
so it can't see exactly where it's going.
206
00:31:59,800 --> 00:32:03,270
Its nearest living relatives are squid and octopus
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which, over evolutionary time,
have both lost their shells.
208
00:32:08,080 --> 00:32:13,110
And the octopus has become
one of the nautilus's major predators.
209
00:32:13,200 --> 00:32:15,990
It's a master of disguise.
210
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The nautilus keeps well clear of them.
211
00:32:27,640 --> 00:32:32,110
Its small tentacles
carry highly-developed chemical sensors
212
00:32:32,200 --> 00:32:36,230
which can detect traces
of both predators and prey.
213
00:32:42,120 --> 00:32:46,110
It uses its water jet to dig in the sand.
214
00:32:51,320 --> 00:32:56,670
Because it devotes so little energy to swimming,
it only needs a meal once a month.
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Got something, and just as well.
216
00:33:05,680 --> 00:33:10,430
Dawn is approaching and
it has to puff its way back to deeper waters.
217
00:33:32,520 --> 00:33:37,990
Thirty miles away, shoals of squid
are jetting upwards towards the surface.
218
00:33:39,760 --> 00:33:44,830
By night, they seek small fish
among the plankton, but they're cautious.
219
00:33:52,240 --> 00:33:54,190
Pacific spotted dolphin.
220
00:33:58,560 --> 00:34:01,310
They're guided by their sonar.
221
00:34:05,800 --> 00:34:09,310
The dolphin, as so often, are working as a team,
222
00:34:09,400 --> 00:34:13,030
synchronising their attacks to confuse their prey.
223
00:34:31,640 --> 00:34:33,110
As dawn approaches,
224
00:34:33,200 --> 00:34:39,270
squid and fish and plankton
retreat downwards to shelter in the darkness.
225
00:35:05,240 --> 00:35:11,510
Some of these isolated volcanoes
rise as much as 9, 000 metres from the sea floor,
226
00:35:11,600 --> 00:35:14,030
reaching close to the surface.
227
00:35:17,840 --> 00:35:21,510
Around these peaks,
invigorated by daily sunshine,
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00:35:21,600 --> 00:35:26,150
marine life flourishes in spectacular abundance.
229
00:35:35,200 --> 00:35:40,550
Fish crowd here because the volcano
forces nutrients to the surface,
230
00:35:40,640 --> 00:35:43,590
encouraging the plankton to bloom.
231
00:36:02,120 --> 00:36:05,110
An oceanic wanderer, a Mola mola,
232
00:36:05,200 --> 00:36:10,110
stops by to be cleaned by reef fish
at the seamount edge.
233
00:36:18,000 --> 00:36:22,790
Butterfly fish pluck string-like parasites
from its flanks.
234
00:36:29,800 --> 00:36:34,150
The huge fish lives on jellyfish
over 1, 000 metres down,
235
00:36:34,240 --> 00:36:37,230
where the water is 20 degrees colder.
236
00:36:38,160 --> 00:36:40,710
So, a brush-up near the surface
237
00:36:40,800 --> 00:36:45,910
allows it to warm up
before making more deep-water forays.
238
00:36:53,640 --> 00:36:58,950
The summit of this volcanic mountain
rises above the surface of the sea.
239
00:37:00,280 --> 00:37:06,070
It's Ascension Island,
800 miles from any other land.
240
00:37:06,160 --> 00:37:10,750
A welcome, vital haven
for long-distance travellers.
241
00:37:15,560 --> 00:37:20,070
Frigate birds spend months
continuously airborne at sea,
242
00:37:20,200 --> 00:37:24,870
but at nesting time,
they come to Ascension from all over the ocean.
243
00:37:29,800 --> 00:37:33,630
The island's barren slopes of volcanic ash and lava
244
00:37:33,720 --> 00:37:37,590
might seem to offer
perfectly good sites for a nest,
245
00:37:39,400 --> 00:37:43,470
but the frigates choose an even more isolated site.
246
00:37:45,280 --> 00:37:50,590
Boatswainbird Island,
a lonely pillar just off Ascension's coast.
247
00:37:59,280 --> 00:38:03,910
Frigates are the world's lightest bird
relative to their wingspan
248
00:38:04,000 --> 00:38:07,550
and they can soar for weeks on end
with minimal effort.
249
00:38:12,440 --> 00:38:17,630
They seem much more at home in the skies
than in a crowded colony on land.
250
00:38:17,720 --> 00:38:19,550
But nest they must.
251
00:38:21,960 --> 00:38:26,350
They come from all over the Atlantic to this,
their only colony.
252
00:38:30,080 --> 00:38:32,150
There are boobies here, too.
253
00:38:37,280 --> 00:38:42,950
To raise their young,
seabirds worldwide seek such remote islands.
254
00:38:53,920 --> 00:38:57,350
Swimmers also come to Ascension to breed.
255
00:38:59,000 --> 00:39:02,630
A female green turtle approaches the coast.
256
00:39:05,760 --> 00:39:09,270
She has not eaten once in two months.
257
00:39:10,520 --> 00:39:14,630
She may have travelled 1, 000 miles
from her feeding grounds.
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00:39:14,720 --> 00:39:17,110
The greatest journey of her kind.
259
00:39:24,760 --> 00:39:30,630
Many others are here, too, resting on
the sandy sea floor awaiting the darkness of night
260
00:39:30,720 --> 00:39:33,550
when it will be safer to visit the beaches.
261
00:39:39,960 --> 00:39:45,550
Eggs that were laid a few weeks ago
at the start of the season are beginning to hatch.
262
00:39:58,400 --> 00:40:00,670
Most hatchings happen at night.
263
00:40:01,640 --> 00:40:05,950
Now, in the light of day,
the young are extremely vulnerable.
264
00:40:12,240 --> 00:40:15,190
They must get to the sea as soon as possible.
265
00:40:17,680 --> 00:40:20,710
But their trials have only just begun.
266
00:40:33,640 --> 00:40:37,590
Many will drown in the pounding waves.
267
00:41:01,880 --> 00:41:07,390
During the next 20 years,
the vast majority will inevitably die.
268
00:41:07,480 --> 00:41:11,830
But those that survive will, eventually,
as their mothers did before them,
269
00:41:11,920 --> 00:41:15,350
return to the very same beach
where they were hatched.
270
00:41:18,080 --> 00:41:22,470
How they find their way back,
across thousands of miles of open ocean,
271
00:41:22,560 --> 00:41:24,830
we still have no idea.
272
00:41:33,400 --> 00:41:35,630
A frigate soars.
273
00:41:37,160 --> 00:41:42,310
Somewhere beneath the surface below
there is the food it must have.
274
00:41:43,360 --> 00:41:44,990
But where?
275
00:41:46,920 --> 00:41:52,510
Those that fly above the ocean
must be able to read the signs of fresh supplies
276
00:41:52,600 --> 00:41:54,150
or perish.
277
00:41:57,120 --> 00:42:02,270
A hundred miles from the Mexican coast
and keen eyes have spotted movement.
278
00:42:07,520 --> 00:42:12,630
Sailfish, three metres long, are closing in on prey.
279
00:42:18,480 --> 00:42:23,390
They will only use just enough energy
to make their kill,
280
00:42:23,480 --> 00:42:25,630
never wasting a fin stroke.
281
00:42:30,520 --> 00:42:34,910
Nearly a hundred sailfish
have surrounded a single school of bait fish.
282
00:42:35,000 --> 00:42:39,310
It's very rare to see
so many of these hunters in one place.
283
00:42:42,480 --> 00:42:47,270
To herd their prey,
the predators raise their huge dorsal fins.
284
00:43:05,040 --> 00:43:09,470
A mistimed strike by one sailfish
could fatally damage another.
285
00:43:09,560 --> 00:43:14,870
But each continually changes its colour
from blue, to striped, to black.
286
00:43:15,000 --> 00:43:20,270
That warns its companions of its intentions
and also confuses the prey.
287
00:43:23,360 --> 00:43:28,550
As the shoal is driven nearer the surface,
it comes within the range of the seabirds.
288
00:43:43,480 --> 00:43:48,630
Out here in the open ocean,
there is nowhere for the bait fish to hide.
289
00:44:31,040 --> 00:44:34,430
Sailfish live a high-octane life.
290
00:44:35,160 --> 00:44:39,030
To survive, they must find prey daily.
291
00:44:39,120 --> 00:44:43,190
So their entire existence
will be spent on the move.
292
00:44:54,640 --> 00:45:00,950
Over 90% of the living space
for life on our planet is in the oceans.
293
00:45:02,280 --> 00:45:07,870
Home to the biggest animal that exists
or has ever existed.
294
00:45:10,040 --> 00:45:12,110
The blue whale.
295
00:45:19,720 --> 00:45:26,630
Some weigh nearly 200 tons,
twice the size of the largest dinosaur.
296
00:45:31,560 --> 00:45:33,510
Despite their great size,
297
00:45:33,600 --> 00:45:38,510
we still have little idea of where they travel
in the vast oceans
298
00:45:38,600 --> 00:45:41,870
and none at all of where they go to breed.
299
00:46:11,120 --> 00:46:15,630
The largest animal on Earth
feeds almost exclusively
300
00:46:15,720 --> 00:46:20,790
on one of the smallest,
krill, shrimp-like crustaceans.
301
00:46:22,920 --> 00:46:28,550
They take many tons of water
into their ballooning throats in a single gulp
302
00:46:28,640 --> 00:46:31,830
and sieve out what it contains.
303
00:46:38,320 --> 00:46:44,110
Every day, each one swallows
some four million krill.
304
00:46:47,080 --> 00:46:53,230
Such gargantuan harvests
depend on the continuing fertility of the oceans.
305
00:46:56,160 --> 00:47:00,710
But global changes now threaten
the great blooms of plankton
306
00:47:00,800 --> 00:47:02,870
on which the whales depend.
307
00:47:05,520 --> 00:47:08,590
Once, and not so long ago,
308
00:47:08,680 --> 00:47:12,510
300,000 blue whales roamed the oceans.
309
00:47:13,480 --> 00:47:17,350
Now, less than 3% of that number remains.
310
00:47:22,160 --> 00:47:25,950
Our planet is still full of wonders.
311
00:47:26,080 --> 00:47:32,070
As we explore them,
so we gain not only understanding, but power.
312
00:47:34,200 --> 00:47:39,110
It's not just the future of the whale
that today lies in our hands.
313
00:47:39,200 --> 00:47:44,830
It's the survival of the natural world
in all parts of the living planet.
314
00:47:46,480 --> 00:47:49,950
We can now destroy or we can cherish.
315
00:47:53,480 --> 00:47:56,630
The choice is ours.
29247
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