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Dwarfed by the vast expanse
of the open ocean
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00:00:39,823 --> 00:00:43,993
the biggest animal
that has ever lived on our planet.
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00:00:50,259 --> 00:00:54,429
A blue whale, 30 metres long
and weighing over 200 tonnes
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00:00:56,525 --> 00:01:00,684
It's far bigger
than even the biggest dinosaur
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00:01:01,748 --> 00:01:04,874
Its tongue weighs as much as an elephant
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00:01:04,875 --> 00:01:08,002
Its heart is the size of a car
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00:01:08,003 --> 00:01:12,163
And some of its blood vessels are so wide
that you could swim down them
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00:01:14,269 --> 00:01:18,429
Its tail alone is the width
of a small aircraft wings
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00:01:38,268 --> 00:01:42,428
Its streamlining, close to perfection,
enables it to cruise at twenty knots
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00:01:43,491 --> 00:01:47,651
It's one of the fastest animals in the sea
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00:01:51,832 --> 00:01:56,002
The ocean's largest inhabitant feeds
Almost exclusively on one of the smallest
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00:01:57,055 --> 00:02:01,215
krill, a crustacean
just a few centimetres long
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00:02:05,406 --> 00:02:09,575
Gathered in a shoal,
krill stain the sea red and a single blue
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00:02:09,576 --> 00:02:13,736
whale in a day
can consume forty million of them
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00:02:23,139 --> 00:02:27,310
Despite the enormous size of blue whales,
we know very little about them
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Their migration
routes are still a mystery and
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00:02:30,448 --> 00:02:34,607
we have absolutely no idea
where they go to breed
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00:02:38,798 --> 00:02:41,925
They are a dramatic reminder of how much
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we still have to learn about the ocean and
the creatures that live there
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00:02:50,277 --> 00:02:52,361
Our planet is a blue planet
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00:02:52,362 --> 00:02:56,522
Over seventy percent of
it is covered by the sea
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00:02:59,670 --> 00:03:01,754
The Pacific Ocean
alone covers half the globe
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00:03:01,755 --> 00:03:04,882
You can fly across it non-stop
for twelve hours
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00:03:04,883 --> 00:03:09,053
and still see nothing
more than a speck of land
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00:03:10,106 --> 00:03:14,266
This series will reveal the complete
natural history of our ocean planet from
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00:03:15,319 --> 00:03:19,489
its familiar shores to the mysteries
of its deepest seas
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By volume, the ocean makes up 97% of
the earth inhabitable space
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And the sheer quantity of marine life
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00:03:39,329 --> 00:03:43,488
it contains far exceeds that
which inhabits the land
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00:04:07,498 --> 00:04:09,593
But life in the ocean
is not evenly spread.
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It's regulated by the path
of currents carrying nutrients
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and the varying power of the sun
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00:04:18,977 --> 00:04:22,114
In this first programme
we will see how these two forces interact
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to control the distribution of life
from the coral seas ...to the polar wastes
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00:05:25,772 --> 00:05:29,932
The sheer physical power
of the ocean dominates our planet
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00:05:47,687 --> 00:05:51,856
It profoundly influences
the weather of all the world
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Water vapour rising
from it forms the clouds
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00:05:53,952 --> 00:05:58,112
and generates the storms that ultimately
will drench the land
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00:06:18,994 --> 00:06:22,121
The great waves
that roar in towards the shores
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00:06:22,122 --> 00:06:26,292
are dramatic demonstrations of its power
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00:06:39,866 --> 00:06:44,035
Waves originate far out at sea
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00:06:44,036 --> 00:06:47,173
There,
even gentle breezes can cause ripples
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00:06:47,174 --> 00:06:51,334
and ripples grow into swells
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00:06:59,695 --> 00:07:03,855
Out in the open ocean, unimpeded by land,
such swells can become gigantic
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00:07:28,918 --> 00:07:32,045
It's only when an ocean swell
eventually reaches shallow water
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that it starts to break
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00:07:42,481 --> 00:07:43,523
As it approaches the coast
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00:07:43,524 --> 00:07:47,684
the water at the bottom of the swell
is slowed by contact with the sea bed
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00:07:48,747 --> 00:07:51,874
The top of the swell,
still travelling fast,
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00:07:51,875 --> 00:07:56,034
starts to roll over
and so the wave breaks
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00:08:28,395 --> 00:08:29,437
The ocean never rests.
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00:08:29,438 --> 00:08:32,575
Huge currents, such as the Gulf Stream,
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keep its waters constantly
on the move all round the globe
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00:08:36,746 --> 00:08:38,830
It's these currents
more than any other factor
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00:08:38,831 --> 00:08:43,001
that control the distribution of
nutrients and life in the seas
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00:08:47,182 --> 00:08:50,308
A tiny island lost in the midst
of the Pacific
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It's the tip of a huge mountain
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that rises precipitously from
the sea floor thousands of metres below
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00:09:02,841 --> 00:09:07,001
The nearest land
is three hundred miles away
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00:09:10,139 --> 00:09:14,318
Isolated sea mounts
like this one create oases
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where life can flourish...
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in the comparatively empty expanses
of the open ocean
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00:09:28,925 --> 00:09:32,052
But all the creatures
that swim beside it would
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00:09:32,053 --> 00:09:36,223
not be here were it not for
one key factor - the deep ocean currents
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Far below the surface they collide with
the island's flanks
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and are deflected upwards
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bringing with them from the depths
a rich soup of nutrients
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00:09:57,105 --> 00:10:01,265
Such up-wellings
attract great concentrations of life
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00:10:09,626 --> 00:10:12,753
Most of the fish here
are permanent residents,
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00:10:12,754 --> 00:10:16,933
feeding on the plankton, the tiny floating
plants and animals that are nourished
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00:10:16,934 --> 00:10:20,061
by the richness brought up from the depths
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00:10:20,062 --> 00:10:24,222
And they in turn,
attract visitors from the open ocean
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Tuna.
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The plankton feeders are easy targets
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All this action attracts
even larger predators...
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Sharks!
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Hundreds of sharks.
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00:11:24,762 --> 00:11:28,942
These silky sharks are
normally ocean-going species
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but the sea mounts in the eastern Pacific,
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like Cocos, Malpelo and the Galapagos,
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attract silkies in huge groups
up to five hundred strong
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00:11:43,549 --> 00:11:46,676
Silkies seem to specialize
in taking injured fish
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00:11:46,677 --> 00:11:50,847
and constantly circle sea mounts on
the look out for the chance to do so
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00:11:57,113 --> 00:12:01,283
But Silkies are not the only visitors
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00:12:03,378 --> 00:12:06,505
Hammerheads gather
in some of the largest shark
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00:12:06,506 --> 00:12:09,643
shoals to be found anywhere in the ocean
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00:12:09,644 --> 00:12:13,804
Sometimes thousands will circle
over a single sea mount
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00:12:19,027 --> 00:12:22,164
But these sharks are not here for food
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00:12:22,165 --> 00:12:26,325
They have come for another reason
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Some of the locals
provide a cleaning service
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Following the last El Nino year,
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when a rise in water temperatures
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caused many sharks to suffer
from fungal infections,
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00:12:43,037 --> 00:12:47,197
the number of hammerheads visiting the sea
mounts reached record levels
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00:12:58,685 --> 00:13:02,856
Nutrients also well up to the surface
along the coasts of the continents
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00:13:05,994 --> 00:13:10,163
This is Natal
on South Africa's eastern seaboard
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00:13:10,164 --> 00:13:14,334
It's June and just off-shore,
strange black patches have appeared
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They look like immense oil
slicks up to a mile long
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00:13:24,780 --> 00:13:27,907
But this is a living slick
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00:13:27,908 --> 00:13:31,035
Millions and millions
of sardines on a marine
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migration that in terms of sheer biomass
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rivals that of the wildebeest
on the grasslands of Africa
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00:13:42,514 --> 00:13:44,609
These fish live for most of the time
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in the cold waters south of the Cape,
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00:13:46,695 --> 00:13:50,864
but each year the coastal currents reverse
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00:13:50,865 --> 00:13:51,906
The warm Agulhas current that
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usually flows down from the north
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has been displaced by cold water
coming up from the south
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00:13:57,130 --> 00:14:00,257
and that has brought up rich nutrients
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00:14:00,258 --> 00:14:04,438
They, in turn,
have created a bloom of plankton
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- and the sardines are now feasting on it
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00:14:16,960 --> 00:14:18,001
As the sardines travel north,
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a whole caravan of predators follow them
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00:14:26,353 --> 00:14:29,480
Thousands of Cape Gannets
track the sardines
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They nested off the Cape
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00:14:30,523 --> 00:14:33,650
and timed their breeding so that
their newly-fledged chicks
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can join them in pursuing the shoals
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00:14:44,087 --> 00:14:48,257
Below water, hundreds of sharks
have also joined the caravan
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00:14:52,438 --> 00:14:54,522
These are Bronze whaler sharks,
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00:14:54,523 --> 00:14:58,693
a cold water species that normally
lives much further south
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00:15:04,958 --> 00:15:08,096
These three-metre sharks
cut such great swathes
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00:15:08,097 --> 00:15:12,256
through the sardine shoals that their
tracks are clearly visible from the air
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00:15:14,352 --> 00:15:18,531
Harried by packs of predators and
swept in by the action of the waves,
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the sardine shoals are penned
close to the shore
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Common dolphin are coming in
from the open ocean to join the feast
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00:16:01,318 --> 00:16:05,478
There are over a thousand of them
in this one school
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00:16:12,797 --> 00:16:16,957
When they catch up with the sardines,
the action really begins
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00:16:21,148 --> 00:16:25,307
Working together,
they drive the shoal towards the surface
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00:16:34,711 --> 00:16:38,871
It is easier for the dolphins
to snatch fish up here
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00:16:52,455 --> 00:16:56,615
Now the sardines have no escape
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00:17:08,104 --> 00:17:12,264
Thanks to the dolphins, the sardines have
come within the diving range of the gannets
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00:17:25,848 --> 00:17:28,975
Hundreds of white arrows shoot
into the sea,
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leaving long trails
of bubbles behind each dive
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00:17:44,635 --> 00:17:48,794
Next to join the frenzy are the sharks
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00:18:01,326 --> 00:18:04,463
Sharks get very excited
when dolphins are around
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That may be because
they can feed particularly...
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00:18:06,549 --> 00:18:07,591
well once the dolphins have driven
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00:18:07,592 --> 00:18:11,751
the sardines into more compact
groups near the surface
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00:18:15,942 --> 00:18:20,102
As the frenzy continues walls of
bubbles drift upwards
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00:18:24,283 --> 00:18:28,453
They are being released by the dolphins,
working together in teams
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00:18:30,548 --> 00:18:34,708
They use the bubbles to corral the
sardines into ever tighter groups
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00:18:38,899 --> 00:18:43,059
The sardines seldom cross the wall of
bubbles and crowd closer together
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00:18:48,293 --> 00:18:52,452
Bubble netting in this way enables the
dolphins to grab every last trapped sardine
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00:19:06,026 --> 00:19:09,163
Just when the feasting
seems to be almost over,
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a Bryde whale arrives
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00:19:15,420 --> 00:19:18,557
The survivors head on northwards,
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00:19:18,558 --> 00:19:22,717
and the caravan of predators follows them
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00:19:30,036 --> 00:19:32,120
Nutrients can also be brought up
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- though less predictably
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- - by rough weather
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Particularly near the poles,
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huge storms stir the depths and
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enrich the surface waters and here,
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in the South Atlantic,
the seas are the roughest on the planet
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And very rich seas they are too, for here,
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the cold Falklands current from the South
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meets the warm Brazil
current from the North
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and at their junction
there is food in abundance
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00:20:09,694 --> 00:20:12,821
These Black-browed
albatross are duck-diving
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for krill that has been driven up
to the surface
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Like all albatross,
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Black-brows are wanderers
across the face of the open ocean
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A feeding assembly on this scale
is a rare sight
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Most of the time,
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the birds of the open sea
are widely dispersed
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But these feeding grounds are close
to an albatross breeding colony
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- and a very special one
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This is Steeple Jason, a remote island
in the far west of the Falklands
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It has the largest albatross
colony in the world
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There are almost half a million
albatross here
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an astonishing demonstration of
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how fertile the ocean can be
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and how much food it can give even to
creatures that do not actually live in it
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Nutrients by themselves are not enough to
generate these vast assemblies.
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00:22:08,659 --> 00:22:10,743
The heat and light
that the sun brings everyday
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is also essential for the growth of
the microscopic floating plants
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- the phytoplankton
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And it the phytoplankton
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that is the basis of all life in the ocean
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Every evening,
the disappearance of the sun
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below the horizon triggers the largest
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migration of life
that takes place on our planet
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One thousand million tones
of sea creatures
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ascend from the deep ocean to
search for food near the surface
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00:23:06,051 --> 00:23:10,231
They graze on the phytoplankton
under cover of darkness
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00:23:10,232 --> 00:23:13,359
Even so, they are far from safe
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00:23:13,360 --> 00:23:15,444
Other marine hunters follow them,
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some travelling up
from hundreds of metres below
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00:24:20,156 --> 00:24:24,315
At dawn, the whole procession returns
to the safety of the dark depths
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00:24:32,677 --> 00:24:36,836
The moon too has a great
influence on life in the oceans
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00:24:38,932 --> 00:24:43,102
Its gravitational pull creates the daily
advance and retreat of the tides
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00:24:56,676 --> 00:24:59,803
But the moon has
more than a daily cycle
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Each month it waxes and wanes
as it travels around the earth,
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and this monthly cycle also
triggers events in the ocean
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The Pacific Coast of Costa Rica
on a very special night
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It just after midnight
and the tide is coming in
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00:25:25,898 --> 00:25:29,025
The moon is in its last quarter,
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exactly half way between full and new
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For weeks the beach has been empty
But that is about to change
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00:25:39,462 --> 00:25:43,622
At high tide,
turtles start to emerge from the surf
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00:25:49,898 --> 00:25:54,058
At first they come in ones and twos,
but within a hour,
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they are appearing all along the beach
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They are all female Ridley turtles
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and over the next six days or so
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00:26:09,727 --> 00:26:12,854
four hundred thousand
will visit this one beach
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00:26:12,855 --> 00:26:17,025
to lay their eggs in the sand
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00:26:23,291 --> 00:26:27,461
At the peak time, five thousand
are coming and going every hour
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00:26:28,514 --> 00:26:30,598
The top of the beach gets so crowded that
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00:26:30,599 --> 00:26:34,768
they have to clamber over one
another to find a bare patch
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where they can dig a nest hole
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00:26:42,077 --> 00:26:44,161
A quarter of the world population
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00:26:44,162 --> 00:26:47,299
of Ridley turtles come to this one beach
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00:26:47,300 --> 00:26:50,427
on a few key nights each year
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00:26:50,428 --> 00:26:53,555
The rest of the time, they are widely
distributed through the ocean
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00:26:53,556 --> 00:26:57,726
searching for food, most
-a hundreds of miles away from here
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00:26:58,779 --> 00:27:01,905
This mass nesting is called an arribada
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00:27:01,906 --> 00:27:03,991
How it is co-ordinated is a mystery
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00:27:03,992 --> 00:27:07,129
- but we do know that's arribadas start
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00:27:07,130 --> 00:27:11,289
when the moon is either in its first
or its last quarter
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00:27:19,651 --> 00:27:23,820
Forty million eggs
are laid in just a few days
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00:27:23,821 --> 00:27:25,905
By synchronising their nesting in this way
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00:27:25,906 --> 00:27:29,043
the females ensure that six weeks later
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00:27:29,044 --> 00:27:32,171
their hatchlings
will emerge in such enormous...
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00:27:32,172 --> 00:27:34,256
numbers that predators on the beach
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00:27:34,257 --> 00:27:37,383
are overwhelmed
and a significant proportion
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00:27:37,384 --> 00:27:41,554
of the baby turtles will get past them
and make it to the water
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00:27:44,693 --> 00:27:46,777
But why do the females
use a cue from the moon
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00:27:46,778 --> 00:27:49,915
to help in synchronising their nesting?
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00:27:49,916 --> 00:27:54,075
Part of the answer to that becomes clear
at dawn on the following morning
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00:28:17,043 --> 00:28:21,213
The day shift of predators are arriving
for their first meals
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00:28:27,479 --> 00:28:29,563
Vultures have learnt
that the returning tide
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00:28:29,564 --> 00:28:33,734
can wash freshly laid eggs out of the sand
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00:28:36,872 --> 00:28:38,956
The risk of eggs being exposed by the surf
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00:28:38,957 --> 00:28:42,094
may be part of the reason
why turtle arribadas
235
00:28:42,095 --> 00:28:46,255
tend to occur around the last
or first quarter of the moon
236
00:28:50,435 --> 00:28:54,615
It's on such days as this,
when the moon is neither full nor new,
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00:28:54,616 --> 00:28:58,776
that the tides are weakest and
the sea is likely to be calmer
238
00:29:13,403 --> 00:29:17,572
So at these times,
it easier for the female turtles
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00:29:17,573 --> 00:29:19,657
to make their way through the surf
240
00:29:19,658 --> 00:29:20,700
and there less chance of their eggs
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00:29:20,701 --> 00:29:24,871
being washed out of the sand
and being taken by the vultures
242
00:29:36,360 --> 00:29:40,529
The moon monthly cycle
and its influence on the tides triggers
243
00:29:40,530 --> 00:29:44,709
many events in the ocean,
from the spawning of the corals
244
00:29:44,710 --> 00:29:48,880
on the Great Barrier reef
to the breeding cycles of fish
245
00:29:48,881 --> 00:29:50,965
But there an even longer rhythm
246
00:29:50,966 --> 00:29:53,050
that has the most profound effect of all
247
00:29:53,051 --> 00:29:57,221
- the annual cycle of the sun
248
00:30:00,359 --> 00:30:02,443
The sun position relative
to the earth changes
249
00:30:02,444 --> 00:30:06,624
through the year and
it this that produces the seasons
250
00:30:06,625 --> 00:30:10,784
In the north, spring comes as the sun
begins to rise higher in the sky
251
00:30:13,922 --> 00:30:16,017
Off the coast of North West America,
252
00:30:16,018 --> 00:30:20,178
the seas are transformed by the increasing
strength of the sunshine
253
00:30:25,411 --> 00:30:28,538
Here in Alaska the coastal waters turn
254
00:30:28,539 --> 00:30:32,699
green with a sudden bloom of phytoplankton
255
00:30:35,847 --> 00:30:38,974
Herring that have spent
the winter far out to sea,
256
00:30:38,975 --> 00:30:42,101
time their return to the shallow waters
to coincide with this bloom
257
00:30:42,102 --> 00:30:45,229
They come in vast numbers and initiate
258
00:30:45,230 --> 00:30:49,400
one of the most productive
food chains in all the oceans
259
00:31:05,059 --> 00:31:09,239
Humpback whales are at the top
of that food chain
260
00:31:09,240 --> 00:31:13,409
They have spent the winter breeding
in the warmer tropical waters off Hawaii
261
00:31:13,410 --> 00:31:15,494
But there was little food for them there
262
00:31:15,495 --> 00:31:19,665
This herring bonanza provides the vast
majority of their food for the year
263
00:31:43,675 --> 00:31:46,802
Stellar and Californian sea lions
264
00:31:46,803 --> 00:31:50,973
also return from the open ocean
each year to feast off the herring
265
00:32:02,462 --> 00:32:05,588
The herring themselves,
however, have not come here for food
266
00:32:05,589 --> 00:32:08,716
They are about to breed
267
00:32:08,717 --> 00:32:12,887
Nothing deters them as they head
for even shallower waters
268
00:32:14,983 --> 00:32:17,067
Now the waters
are so shallow that glaucous
269
00:32:17,068 --> 00:32:21,238
-winged gulls are able to snatch live fish
from just below the surface
270
00:32:33,769 --> 00:32:35,854
In spite of these attacks and losses,
271
00:32:35,855 --> 00:32:37,939
the herring swim on until
272
00:32:37,940 --> 00:32:40,024
they reach the vegetation that the females
273
00:32:40,025 --> 00:32:44,195
need if they are to lay
274
00:32:48,376 --> 00:32:52,555
Each female produces
around twenty thousand eggs
275
00:32:52,556 --> 00:32:56,716
- and they every sticky
276
00:32:58,811 --> 00:33:00,896
The males arrive soon after the females
277
00:33:00,897 --> 00:33:05,067
have spawned and release their sperm
in vast milky clouds
278
00:33:10,290 --> 00:33:14,469
Soon the excesses
of the herrings' sexual spree
279
00:33:14,470 --> 00:33:18,630
creates a thick, white scum on the surface
280
00:33:19,683 --> 00:33:23,853
Through the season curds of sperm clog
the shores for hundreds of miles,
281
00:33:24,906 --> 00:33:29,066
from British Columbia in the South
all the way to Alaska in the north
282
00:33:36,385 --> 00:33:38,469
After a few days this gigantic spawning
283
00:33:38,470 --> 00:33:42,639
comes to an end and the herring head
back out to deeper waters,
284
00:33:42,640 --> 00:33:45,777
leaving behind them
fertilised eggs plastered...
285
00:33:45,778 --> 00:33:49,938
on every rock and strand of vegetation
286
00:34:01,427 --> 00:34:03,511
They time their spawning
so that two weeks later,
287
00:34:03,512 --> 00:34:05,606
when these eggs start to hatch,
288
00:34:05,607 --> 00:34:07,691
the annual plankton bloom
will have reached
289
00:34:07,692 --> 00:34:09,776
its height and the new-born fish fry
290
00:34:09,777 --> 00:34:11,862
will have plenty to eat
291
00:34:11,863 --> 00:34:15,000
But in the meantime,
all these eggs provide food
292
00:34:15,001 --> 00:34:19,160
for armies of different animals both below
and above the surface
293
00:34:27,522 --> 00:34:31,691
Millions of birds arrive to collect
a share of the herring bounty
294
00:34:31,692 --> 00:34:33,776
Some of it is easily gathered,
295
00:34:33,777 --> 00:34:37,947
for millions of eggs have been
washed up onto the shore
296
00:34:39,000 --> 00:34:43,160
This encapsulated energy is particularly
valuable to migrating birds
297
00:34:45,255 --> 00:34:47,350
These surfbirds are on their way
298
00:34:47,351 --> 00:34:50,477
to their breeding grounds in the Arctic
299
00:34:50,478 --> 00:34:51,520
and they have to come down to refuel
300
00:34:51,521 --> 00:34:55,681
Stranded herring eggs
are just what they need
301
00:34:57,787 --> 00:35:01,946
Bonaparte gulls collect the eggs
just below the surface of the water
302
00:35:05,085 --> 00:35:09,264
Further out in the bay,
huge flocks of ducks have gathered
303
00:35:09,265 --> 00:35:11,349
They are mostly surf scoters
304
00:35:11,350 --> 00:35:15,510
- diving ducks - that can feed off
the bottom several metres down
305
00:35:19,701 --> 00:35:21,785
There are such huge quantities of eggs
306
00:35:21,786 --> 00:35:24,913
that even such a big animal as a bear
307
00:35:24,914 --> 00:35:29,084
finds it worthwhile to collect them
308
00:35:31,179 --> 00:35:34,306
The spawning of the herring
is a crucial event
309
00:35:34,307 --> 00:35:37,434
in the lives of many animals
all along the coast
310
00:35:37,435 --> 00:35:40,572
The whole event coincides
with the plankton bloom
311
00:35:40,573 --> 00:35:44,733
and within just three short weeks
it all over
312
00:35:49,966 --> 00:35:54,126
The migratory birds leave
to continue their journey north
313
00:36:02,487 --> 00:36:06,647
They will not come back until
the herring also return next year
314
00:36:12,923 --> 00:36:15,007
As the herring spawning finishes,
315
00:36:15,008 --> 00:36:19,168
other migrants are starting
to arrive just offshore
316
00:36:21,274 --> 00:36:25,433
Grey whales
317
00:36:27,529 --> 00:36:29,613
They have followed the sun north
318
00:36:29,614 --> 00:36:31,709
and they too are seeking the food
319
00:36:31,710 --> 00:36:35,869
that is generated by
the bloom of the phytoplankton
320
00:36:39,007 --> 00:36:43,187
Krill are feeding off it and these
whales are feeding on the krill,
321
00:36:43,188 --> 00:36:46,315
skimming it from the surface
with the filter plates of baleen
322
00:36:46,316 --> 00:36:50,475
that hang from their upper jaws
323
00:36:52,581 --> 00:36:54,665
Grey whales make one
of the longest migrations
324
00:36:54,666 --> 00:36:56,751
undertaken by any marine mammal
325
00:36:56,752 --> 00:36:59,878
- a round trip of 12,000 miles or
326
00:36:59,879 --> 00:37:01,974
so from their breeding grounds off Mexico
327
00:37:01,975 --> 00:37:05,101
along the entire coast of North America
328
00:37:05,102 --> 00:37:09,262
right up to the Arctic ocean
329
00:37:10,315 --> 00:37:12,410
They travel close to the coast
with the males
330
00:37:12,411 --> 00:37:16,580
and non-breeding females leading the way
331
00:37:16,581 --> 00:37:19,707
The last to start are the cows
that have just given birth
332
00:37:19,708 --> 00:37:21,792
They have to wait until
their new-born calves
333
00:37:21,793 --> 00:37:25,964
are sufficiently big and strong to tackle
such an immense journey
334
00:37:29,102 --> 00:37:32,228
Their progress is necessarily slow
335
00:37:32,229 --> 00:37:34,324
The mothers must stay
alongside their young
336
00:37:34,325 --> 00:37:38,485
and even a strong calf can only travel
at a couple of knots
337
00:37:39,538 --> 00:37:41,622
They stick even closer to the shore
338
00:37:41,623 --> 00:37:45,793
often within just 200 metres
339
00:37:48,931 --> 00:37:51,015
Killer whales.
340
00:37:51,016 --> 00:37:55,186
They have learnt that grey whales
follow traditional routes
341
00:37:56,239 --> 00:37:58,323
The killers have no trouble in overtaking
342
00:37:58,324 --> 00:38:02,484
a calf and its devoted mother
343
00:38:05,633 --> 00:38:07,717
Normally,
they continually call to one another,
344
00:38:07,718 --> 00:38:10,844
but now they have fallen silent
345
00:38:10,845 --> 00:38:15,005
The mother grey whale and her calf
have no idea that they have been targeted
346
00:38:37,983 --> 00:38:42,152
Catching up with the grey whales
is the easy part for the killers
347
00:38:42,153 --> 00:38:44,237
They have to be cautious
for they are only...
348
00:38:44,238 --> 00:38:48,408
about half the size
of the grey whale mother
349
00:38:50,504 --> 00:38:54,663
She can inflict real damage with her tail
350
00:39:03,025 --> 00:39:07,204
But the killers are not after her
They are after her calf
351
00:39:07,205 --> 00:39:09,289
As long as the mother
can keep it on the move,
352
00:39:09,290 --> 00:39:13,450
it will be safe and
she does her best to hurry it along
353
00:39:16,588 --> 00:39:18,683
At first the killers
avoid getting too close...
354
00:39:18,684 --> 00:39:21,810
to the mother but just keep pace alongside
355
00:39:21,811 --> 00:39:22,853
They know that the calf,
356
00:39:22,854 --> 00:39:27,014
going at this speed, will eventually tire
357
00:39:36,417 --> 00:39:39,554
After three hours
of being harried in this way
358
00:39:39,555 --> 00:39:42,682
the calf becomes too exhausted
to swim any further
359
00:39:42,683 --> 00:39:45,810
The mother has to stop
360
00:39:45,811 --> 00:39:48,948
This is the moment the killers
have been waiting for
361
00:39:48,949 --> 00:39:53,109
They start to try and force themselves
between mother and calf
362
00:40:15,033 --> 00:40:17,117
A calf, separated from its mother,
363
00:40:17,118 --> 00:40:19,202
will not be able to defend itself
364
00:40:19,203 --> 00:40:21,298
Time and again the black fins
365
00:40:21,299 --> 00:40:25,459
of the killers appear between
the mottled backs of the grey whales
366
00:40:36,948 --> 00:40:39,032
At last the killers succeed
367
00:40:39,033 --> 00:40:43,203
And now that they've got the calf
on its own, they change their tactics
368
00:40:44,256 --> 00:40:48,416
They leap right on to the calf
and try to push it under
369
00:40:59,904 --> 00:41:04,075
They are trying to drown it
370
00:41:11,383 --> 00:41:15,553
The calf snatches a desperate breath
371
00:41:28,084 --> 00:41:31,211
The mother becomes increasingly agitated
372
00:41:31,212 --> 00:41:33,307
Frantically,
she tries to push her calf back
373
00:41:33,308 --> 00:41:37,467
to the surface so that it can breathe
374
00:41:40,605 --> 00:41:44,776
But now it is so exhausted that it has
to be supported by its mother's body
375
00:42:03,562 --> 00:42:04,614
The killers won't give up
376
00:42:04,615 --> 00:42:08,775
Like a pack of wolves,
they take turns in harassing the whales
377
00:42:31,742 --> 00:42:35,902
Now the whole pod is involved
378
00:42:45,306 --> 00:42:49,476
One of them takes a bite
379
00:42:59,922 --> 00:43:04,091
Soon the sea is reddened
with the calf's blood
380
00:43:04,092 --> 00:43:08,263
and the killers close in for the final act
381
00:43:29,145 --> 00:43:33,305
The calf is dead
382
00:43:35,400 --> 00:43:39,570
After a six-hour hunt, the killer whales
have finally won their prize
383
00:43:46,878 --> 00:43:51,049
The mother, bereft, has to continue
her migration north on her own
384
00:43:57,314 --> 00:44:00,451
She leaves behind the carcass
of a calf that
385
00:44:00,452 --> 00:44:03,579
she cherished
for thirteen months in her womb
386
00:44:03,580 --> 00:44:07,740
for which she delayed
her own journey to find food
387
00:44:10,888 --> 00:44:15,048
The pod of fifteen killer whales spent
over six hours trying to kill this calf
388
00:44:16,101 --> 00:44:18,185
But now, having succeeded,
389
00:44:18,186 --> 00:44:22,356
they have eaten nothing
more than its lower jaw and its tongue
390
00:44:30,717 --> 00:44:34,877
Valuable food like this will not
go to waste in the ocean
391
00:44:35,930 --> 00:44:40,090
Before long the carcass will sink
to the very bottom of this deep sea
392
00:44:41,153 --> 00:44:45,313
But even there,
its flesh will not be wasted
393
00:44:47,409 --> 00:44:51,588
Over a mile down in the
total darkness of the deep ocean
394
00:44:51,589 --> 00:44:55,758
- the body of another grey whale,
a thirty ton adult
395
00:44:55,759 --> 00:44:59,919
It settled here only a few weeks ago
396
00:45:00,972 --> 00:45:05,142
Already,
it has attracted hundreds of hagfish
397
00:45:11,408 --> 00:45:13,503
These scavengers, over half a metre long
398
00:45:13,504 --> 00:45:17,673
and as thick as your arm,
are only found in the deep sea
399
00:45:17,674 --> 00:45:20,800
They have been attracted
by the faint whiff of
400
00:45:20,801 --> 00:45:24,972
decay suffusing through the water
for miles around
401
00:45:29,152 --> 00:45:31,236
With their heads buried
in the whale's flesh,
402
00:45:31,237 --> 00:45:35,407
they breathe through gill openings
along the sides of their bodies
403
00:45:36,460 --> 00:45:38,544
They're very primitive creatures
404
00:45:38,545 --> 00:45:41,672
- not even true fish, for they lack jaws.
405
00:45:41,673 --> 00:45:44,810
- They feed, not by biting, but by
406
00:45:44,811 --> 00:45:48,971
rasping off flesh
with two rows of horny teeth
407
00:45:50,024 --> 00:45:51,065
In just a few hours,
408
00:45:51,066 --> 00:45:55,237
a hagfish can eat several times
its own weight of rotting flesh
409
00:46:00,460 --> 00:46:04,620
Next to arrive - a sleeper shark
410
00:46:09,853 --> 00:46:12,980
It moves so slowly to conserve energy
411
00:46:12,981 --> 00:46:15,075
- an important strategy for so large
412
00:46:15,076 --> 00:46:19,236
an animal surviving in such a poor habitat
413
00:46:25,512 --> 00:46:28,639
Sleeper sharks live over a mile down
414
00:46:28,640 --> 00:46:32,800
and grow to over seven metres long
415
00:46:33,853 --> 00:46:36,990
They can go for months without food,
416
00:46:36,991 --> 00:46:41,160
slowly cruising along the bottom,
waiting for rare bonanzas,
417
00:46:41,161 --> 00:46:45,321
such as this one, to arrive from above
418
00:46:51,597 --> 00:46:54,723
A whole range of different
deep-sea scavengers
419
00:46:54,724 --> 00:46:57,861
will feast on this carcass for a long time
420
00:46:57,862 --> 00:47:02,022
before all its nutriment has been consumed
421
00:47:03,075 --> 00:47:07,235
Eighteen months later, all that is left
is a perfect skeleton, stripped bare
422
00:47:12,468 --> 00:47:13,510
The sun's energy that was captured
423
00:47:13,511 --> 00:47:16,638
and turned into living tissue
by the floating
424
00:47:16,639 --> 00:47:18,733
phytoplankton has been transferred from
425
00:47:18,734 --> 00:47:20,818
one link to another in the food chain
426
00:47:20,819 --> 00:47:23,946
and has ended up as far away from the sun
427
00:47:23,947 --> 00:47:26,031
as it is possible to be on this planet
428
00:47:26,032 --> 00:47:29,169
- at the bottom of the deep sea
429
00:47:29,170 --> 00:47:33,330
But some energy also returns from the deep
430
00:47:39,606 --> 00:47:43,766
Millions of opalescent squid are
on their way to the shallows
431
00:47:45,861 --> 00:47:46,903
They have come up here to mate
432
00:47:46,904 --> 00:47:51,074
As the males grab the females,
their tentacles flush red
433
00:47:54,212 --> 00:47:55,253
For most of the year these squid
434
00:47:55,254 --> 00:47:58,381
live at a depth of around 500 metres
435
00:47:58,382 --> 00:48:02,562
They only come together in these great
breeding schools for a few weeks
436
00:48:02,563 --> 00:48:06,722
Just one school was estimated to contain
animals that weigh around 4000 tonnes
437
00:48:21,349 --> 00:48:23,433
Wave after wave rise from the depths
438
00:48:23,434 --> 00:48:25,519
and soon the seabed
in the shallows is strewn
439
00:48:25,520 --> 00:48:29,679
with dense patches of egg capsules
several metres across
440
00:48:35,955 --> 00:48:39,082
As each female adds
another capsule to the pile
441
00:48:39,083 --> 00:48:43,253
the males fight to fertilise its contents
442
00:48:58,912 --> 00:49:00,996
The squid make their huge journey
443
00:49:00,997 --> 00:49:03,092
into the shallows because their eggs
444
00:49:03,093 --> 00:49:06,220
will develop faster
in the warmer water here
445
00:49:06,221 --> 00:49:08,305
and when the young emerge,
they will find more
446
00:49:08,306 --> 00:49:12,465
food more easily than
they would in the ocean depths
447
00:49:17,699 --> 00:49:21,859
Dawn the next morning and the seabed for
miles around is covered in egg capsules.
448
00:49:25,007 --> 00:49:27,091
The squid themselves have all gone
449
00:49:27,092 --> 00:49:31,252
Many will have died, but some will have
returned to their home in the deep
450
00:49:32,305 --> 00:49:34,400
They will not return
to the light of the sun
451
00:49:34,401 --> 00:49:38,560
until the next time they are driven up
by the urge to spawn
37179
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