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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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And some of its blood vessels are so wide
that you could swim down them

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Its tail alone is the width
of a small aircraft wings

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Its streamlining, close to perfection,
enables it to cruise at twenty knots

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It's one of the fastest animals in the sea

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The ocean's largest inhabitant feeds
Almost exclusively on one of the smallest

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krill, a crustacean
just a few centimetres long

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Gathered in a shoal,
krill stain the sea red and a single blue

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whale in a day
can consume forty million of them

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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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we have absolutely no idea
where they go to breed

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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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Our planet is a blue planet

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Over seventy percent of
it is covered by the sea

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The Pacific Ocean
alone covers half the globe

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You can fly across it non-stop
for twelve hours

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and still see nothing
more than a speck of land

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This series will reveal the complete
natural history of our ocean planet from

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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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it contains far exceeds that
which inhabits the land

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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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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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The sheer physical power
of the ocean dominates our planet

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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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and generates the storms that ultimately
will drench the land

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The great waves
that roar in towards the shores

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are dramatic demonstrations of its power

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Waves originate far out at sea

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There,
even gentle breezes can cause ripples

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and ripples grow into swells

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Out in the open ocean, unimpeded by land,
such swells can become gigantic

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It's only when an ocean swell
eventually reaches shallow water

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that it starts to break

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As it approaches the coast

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the water at the bottom of the swell
is slowed by contact with the sea bed

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The top of the swell,
still travelling fast,

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starts to roll over
and so the wave breaks

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The ocean never rests.

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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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It's these currents
more than any other factor

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that control the distribution of
nutrients and life in the seas

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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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The nearest land
is three hundred miles away

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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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But all the creatures
that swim beside it would

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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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Such up-wellings
attract great concentrations of life

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Most of the fish here
are permanent residents,

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feeding on the plankton, the tiny floating
plants and animals that are nourished

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by the richness brought up from the depths

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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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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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Silkies seem to specialize
in taking injured fish

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and constantly circle sea mounts on
the look out for the chance to do so

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But Silkies are not the only visitors

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Hammerheads gather
in some of the largest shark

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shoals to be found anywhere in the ocean

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Sometimes thousands will circle
over a single sea mount

88
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But these sharks are not here for food

89
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They have come for another reason

90
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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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the number of hammerheads visiting the sea
mounts reached record levels

95
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Nutrients also well up to the surface
along the coasts of the continents

96
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This is Natal
on South Africa's eastern seaboard

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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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But this is a living slick

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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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These fish live for most of the time

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in the cold waters south of the Cape,

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but each year the coastal currents reverse

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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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and that has brought up rich nutrients

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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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As the sardines travel north,

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a whole caravan of predators follow them

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Thousands of Cape Gannets
track the sardines

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They nested off the Cape

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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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Below water, hundreds of sharks
have also joined the caravan

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These are Bronze whaler sharks,

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a cold water species that normally
lives much further south

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These three-metre sharks
cut such great swathes

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through the sardine shoals that their
tracks are clearly visible from the air

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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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There are over a thousand of them
in this one school

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When they catch up with the sardines,
the action really begins

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Working together,
they drive the shoal towards the surface

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It is easier for the dolphins
to snatch fish up here

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Now the sardines have no escape

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Thanks to the dolphins, the sardines have
come within the diving range of the gannets

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Hundreds of white arrows shoot
into the sea,

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leaving long trails
of bubbles behind each dive

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Next to join the frenzy are the sharks

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Sharks get very excited
when dolphins are around

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That may be because
they can feed particularly...

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well once the dolphins have driven

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the sardines into more compact
groups near the surface

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As the frenzy continues walls of
bubbles drift upwards

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They are being released by the dolphins,
working together in teams

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They use the bubbles to corral the
sardines into ever tighter groups

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The sardines seldom cross the wall of
bubbles and crowd closer together

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Bubble netting in this way enables the
dolphins to grab every last trapped sardine

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Just when the feasting
seems to be almost over,

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a Bryde whale arrives

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The survivors head on northwards,

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and the caravan of predators follows them

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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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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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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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They graze on the phytoplankton
under cover of darkness

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Even so, they are far from safe

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Other marine hunters follow them,

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some travelling up
from hundreds of metres below

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At dawn, the whole procession returns
to the safety of the dark depths

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The moon too has a great
influence on life in the oceans

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Its gravitational pull creates the daily
advance and retreat of the tides

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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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00:25:29,026 --> 00:25:33,186
exactly half way between full and new

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00:25:35,292 --> 00:25:39,461
For weeks the beach has been empty
But that is about to change

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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

203
00:26:04,514 --> 00:26:07,641
They are all female Ridley turtles

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00:26:07,642 --> 00:26:09,726
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

207
00:26:23,291 --> 00:26:27,461
At the peak time, five thousand
are coming and going every hour

208
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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00:26:34,769 --> 00:26:38,939
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

217
00:27:01,906 --> 00:27:03,991
How it is co-ordinated is a mystery

218
00:27:03,992 --> 00:27:07,129
- but we do know that's arribadas start

219
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

222
00:27:25,906 --> 00:27:29,043
the females ensure that six weeks later

223
00:27:29,044 --> 00:27:32,171
their hatchlings
will emerge in such enormous...

224
00:27:32,172 --> 00:27:34,256
numbers that predators on the beach

225
00:27:34,257 --> 00:27:37,383
are overwhelmed
and a significant proportion

226
00:27:37,384 --> 00:27:41,554
of the baby turtles will get past them
and make it to the water

227
00:27:44,693 --> 00:27:46,777
But why do the females
use a cue from the moon

228
00:27:46,778 --> 00:27:49,915
to help in synchronising their nesting?

229
00:27:49,916 --> 00:27:54,075
Part of the answer to that becomes clear
at dawn on the following morning

230
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

232
00:28:29,564 --> 00:28:33,734
can wash freshly laid eggs out of the sand

233
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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that the tides are weakest and
the sea is likely to be calmer

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00:29:13,403 --> 00:29:17,572
So at these times,
it easier for the female turtles

239
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

241
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