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Our Planet is the greatest living
puzzle in the universe.
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A collection of worlds
within worlds.
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Each one a self-contained ecosystem
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00:00:12,400 --> 00:00:14,400
bursting with life.
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But how do they work?
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The intricate web of relationships
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and the influence of natural forces
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makes each microworld
complex and unique.
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So, to discover their secrets,
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we need to explore them one by one.
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Untangle their interlocking pieces
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and ultimately reveal
the vital piece,
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the key to life itself
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00:00:50,240 --> 00:00:54,640
hidden deep within each
of nature's microworlds.
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Galapagos is arguably
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the most pristine archipelago
on Earth.
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It's a unique living world
of truly enchanting islands.
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Nowhere else on our planet
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are the connections and dependencies
within ecosystems so clear.
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Charles Darwin was the first
to see this
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when he visited the islands
over 170 years ago,
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but, as we will discover,
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he only saw part of the picture.
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What the makes the Galapagos
so unique
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is that many of the creatures
that live here
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are found nowhere else on Earth.
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Even more extraordinary
is that there is life here at all
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on these barren, isolated islands.
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And what life!
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It's a bizarre collection
of creatures...
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..from swimming lizards
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to tropical penguins
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and cormorants that can't fly.
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How has a place
so harsh and isolated
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become a showcase for evolution
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and home to such a motley crew
of creatures?
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00:02:47,360 --> 00:02:50,240
And what is the pivotal piece
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that links all these animals
to each other
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and to the islands they inhabit?
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To discover that,
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we must look at how these islands
were created in the first place.
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Galapagos lies on the Equator,
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600 miles off the coast of Ecuador.
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In this isolation
lies part of the reason
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for the archipelago's
unique wildlife.
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These islands are not
a broken off piece of a continent.
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And they haven't been created
from coral reefs
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like some other tropical
archipelagos.
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This microworld has been born
from forces deep within the Earth.
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Galapagos is one of the most
volcanic places on the planet.
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And it regularly proves it
with spectacular geological shows.
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The archipelago is
plumbed into Earth's molten core.
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The islands have been created
by a unique quirk of geology,
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known to scientists
as the Galapagos hotspot.
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It's a thin part
of the Earth's crust
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that periodically pushes up
molten rock towards the surface.
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And the eruptions create islands.
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For 20 million years,
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the hotspot has continued
to give birth to new land.
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As new islands form,
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they are carried away
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from the hotspot
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on shifting tectonic plates
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towards South America
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creating the string of islands
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we see today.
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This raw geology makes for
a very tough place to live.
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And affects the bizarre creatures
and relationships in Galapagos.
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00:04:54,760 --> 00:04:59,480
But how did life get all the way
out here in the first place?
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To colonise such remote islands,
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life would face
many daunting challenges.
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To get here, any living thing would
first have to cross 600 miles
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of open ocean
from the nearest mainland.
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Plants are the first
pioneers of any new landscape.
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Their seeds float here
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or are blown in,
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or they may be carried in the
feathers or droppings of sea birds.
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Just getting here is
a formidable challenge.
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Getting a foothold in the lava
landscape is something else.
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But life finds a way.
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The whole terrestrial system
is dependant on a few plants
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to kick start the colonisation.
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Mangroves are true ocean voyagers.
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Their seeds are tough enough
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to withstand the desiccating effect
of months in salt water.
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Lava cactus pioneer
the colonisation of the land.
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While Opuntia cactus open up
the land still further.
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With so few species,
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the delicate dependencies
between those species
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makes for some
incredible relationships.
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Many of the native flowering
plants in Galapagos are yellow.
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And that's because
the only species of bee
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that's managed to make it here
and pollinates the flowers
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is attracted to yellow.
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So there's little point in being
anything else.
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The integrity of the food chain
relies on the few insects
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pollinating the plants,
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because the next layer of creatures
depend on them.
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Reptiles are a true hallmark
of Galapagos,
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not necessarily because they deal
better with the conditions here,
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but because they managed to get here
in the first place.
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Reptiles are adept at surviving
in salt water,
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so they stand a good chance of
getting through a vast ocean
crossing.
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Once here, they had to adapt
to what's on offer
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and, in doing so, became the next
integral layer of the ecosystem.
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Land iguanas rely on Opuntia
cactus as their staple food.
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On the more barren islands,
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the shells of saddle back
giant tortoises
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have evolved quirky shapes to allow
them to stretch their necks upwards
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to higher, tasty cactus morsels.
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00:08:10,360 --> 00:08:13,280
But the cactus also
relies on the tortoise.
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They spread their seeds in their
droppings as they roam the islands.
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At the top of the food chain, the
surprising relationships continue.
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The top predator here
isn't what you might expect.
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This is the Galapagos hawk.
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The challenge for a female hawk
is to find enough food
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to raise her young
in such a barren place.
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With next to no small
mammals to hunt
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she turns her attention
to what dominates the land here.
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Marine iguanas nest for only
a few weeks each year.
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Which doesn't leave her much time.
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But she simply must succeed.
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One life ends...
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..and another begins.
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But there's another reason
so many creatures here,
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like the Galapagos hawk,
are endemic,
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found nowhere else on Earth.
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In Galapagos, we see unique species
everywhere we look.
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Not just on land, but also at sea.
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Galapagos sea lions might
look like any other sea lion.
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00:10:11,320 --> 00:10:13,640
But the science proves otherwise.
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Their ancestors arrived here from
California 2.5 million years ago,
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00:10:19,560 --> 00:10:21,880
but they've continued to evolve here
in isolation
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and are now so different
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they're considered a new species.
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Though they come ashore to breed,
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water is their natural environment
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and they depend
on the richness of the seas.
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The flightless cormorant
is a real Galapagos oddity
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and has evolved to suit
a purely aquatic existence.
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With no real land predators
to escape from,
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flight was of limited use.
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Under water their wings were
actually a hindrance,
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and, over time, they dwindled
to mere stubs.
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The entire species are now bound
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to a tiny stretch
of the Galapagos coast.
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Even some creatures that can easily
leave the islands
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are also considered endemic.
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Like the waved albatross.
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After months fishing
further out at sea,
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the first touchdown
isn't always graceful.
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95% of the world's population
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return to just one Galapagos island
each year to breed.
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These birds mate for life.
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The first challenge is
to find their partners.
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When they do, they rekindle their
relationship with a delightful duet.
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THEY SQUAWK
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Over the last few hundred years,
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the Galapagos has been
seen as a living laboratory,
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helping us to understand
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how creatures specialise
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and evolve to
suit their environment.
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There is one example,
above all others,
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that reveals just that -
Darwin's finches.
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Few terrestrial birds managed to
make it to these isolated islands.
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The finches that did make it
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now fill all the various niches
available.
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The finches share a common ancestor,
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but have evolved into
many different forms
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to exploit their new habitats.
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Different finches each
rely on different plants
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and creatures to make a living.
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They have evolved to take
the place of woodpeckers.
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They've become tool users.
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Others have developed larger
beaks for cracking seeds.
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They've even turned into vampires.
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These finches learnt that sea bird
blood makes a nutritious meal,
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full of protein and minerals.
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These avian vampires
don't kill their host,
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though the blood meal must surely
weaken the larger bird.
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Galapagos finches are such a clear
example of how creatures can evolve
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that Darwin eventually saw
in these little birds
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the foundations for his big theories
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on evolution by natural selection.
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These would shock the world
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and revolutionise biology.
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But there is a further key
to working out how all this life
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is interconnected and intrinsically
linked to the islands.
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Something even Darwin
didn't realise.
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To discover what that is,
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we must look to where island life
concentrates -
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the coast.
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00:14:29,120 --> 00:14:32,760
The community of coastal creatures
is heavily interlinked
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and the dependency between them
is clear to see.
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Sally Lightfoot crabs clean dead
skin off the basking marine iguanas.
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Lava lizards also use
the iguanas as lookout posts.
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These endemic animals
are true opportunists.
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00:15:00,600 --> 00:15:03,200
Any advantage here is worth taking.
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Sea lions become hunting grounds.
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It's a relationship that works
for everyone.
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Well, except the fly.
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00:15:22,520 --> 00:15:27,520
On the coast, we see creatures
that depend on the land to breed.
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And on the seas to feed.
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Their lives are linked to the sea.
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00:16:08,520 --> 00:16:11,760
There is something special
about the seas here
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that all coastal creatures rely on.
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And a clue to what that is can be
found beneath the beds of lava.
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There is one seabird here that you'd
never expect to find on the equator.
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The world's only tropical penguins.
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These lava tubes once flowed
with molten magma.
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Now the penguins rely on them
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00:16:39,800 --> 00:16:44,520
to hide their vulnerable
chicks from the baking sun.
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00:16:44,520 --> 00:16:48,040
But the real secret to how Galapagos
penguins can survive here
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00:16:48,040 --> 00:16:51,120
is down to something in the seas.
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00:16:57,360 --> 00:16:59,760
Although the archipelago lies
in the path
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of a number of warm water systems,
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Galapagos is also washed
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by a tongue of cold, Antarctic water
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called the Humboldt Current.
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00:17:12,280 --> 00:17:14,040
The penguin's ancestors
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were brought to Galapagos by that
cool Humboldt Current,
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00:17:18,840 --> 00:17:21,840
and it continues to sustain the
surviving population to this day.
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00:17:28,440 --> 00:17:31,920
This cooler water holds more
life-giving oxygen
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00:17:31,920 --> 00:17:36,000
than warmer tropical waters that are
typically found at this latitude.
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00:17:38,400 --> 00:17:42,640
The cool water combines
with the equatorial sun
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00:17:42,640 --> 00:17:45,280
to feed the marine ecosystem.
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00:17:45,280 --> 00:17:49,600
It makes for one of the most
productive tropical marine
environments in the world.
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00:17:51,840 --> 00:17:56,880
All sea creatures depend on these
life-giving currents.
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It's the reason the fish life
so is rich,
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00:18:01,600 --> 00:18:03,880
both in abundance and diversity.
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00:18:11,560 --> 00:18:16,000
The volcanic character
of the islands also plays its part.
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00:18:22,840 --> 00:18:25,320
The flanks of the volcanoes
draw cold water up
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00:18:25,320 --> 00:18:27,400
from the deep ocean to the surface.
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00:18:30,640 --> 00:18:33,680
It makes the seas around the
youngest, most barren islands
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00:18:33,680 --> 00:18:37,680
the most productive
in the archipelago.
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00:18:37,680 --> 00:18:40,160
And it is here that we find
the largest communities
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00:18:40,160 --> 00:18:43,040
of a truly bizarre creature
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00:18:43,040 --> 00:18:47,080
that has evolved a lifestyle linked
to the productivity of the seas.
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00:18:50,040 --> 00:18:52,880
Galapagos Marine iguanas
are the only sea-going lizard
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00:18:52,880 --> 00:18:54,800
found in the whole world.
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00:18:57,360 --> 00:19:00,480
The barren lava shore offers
little to feed on,
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00:19:00,480 --> 00:19:05,320
so it's not surprising that
their terrestrial ancestors
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00:19:05,320 --> 00:19:08,160
took to the rich waters
to find food.
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00:19:12,360 --> 00:19:16,120
What is astonishing is that they've
evolved to eat only marine algae.
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00:19:20,760 --> 00:19:24,640
But in doing this,
the iguanas face a dilemma.
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00:19:24,640 --> 00:19:28,160
They need the algae
but it lies in cold water,
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00:19:28,160 --> 00:19:32,160
a real problem for
a cold-blooded creature.
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00:19:34,400 --> 00:19:38,240
If they get too chilled, they become
sluggish and eventually can't swim.
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00:19:38,240 --> 00:19:41,520
So they need to offset
periods of diving
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00:19:41,520 --> 00:19:46,080
with time spent
in strong equatorial sun.
251
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We can see how it works by looking
at the iguanas in thermal imagery.
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As they bask, the lethal chill
is driven away,
253
00:19:58,560 --> 00:20:01,800
giving them more energy
to take the plunge again.
254
00:20:05,360 --> 00:20:07,960
By raising their temperature
to 37 degrees centigrade,
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they buy themselves time.
256
00:20:11,560 --> 00:20:14,320
They can return to the cold
water to find the algae.
257
00:20:16,480 --> 00:20:21,480
Smaller, younger individuals
forage in the shallows.
258
00:20:21,560 --> 00:20:25,720
The larger individuals must dive
deeper and for longer
259
00:20:25,720 --> 00:20:29,960
to tap the richer pastures that will
sustain their greater size.
260
00:20:38,040 --> 00:20:42,720
Larger males can hold their breath
for up to 30 minutes.
261
00:20:42,720 --> 00:20:45,520
But the clock is ticking.
262
00:20:49,160 --> 00:20:54,200
It is crucial to find food,
feed and get out.
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00:21:03,680 --> 00:21:05,520
They return to the safety of shore
264
00:21:05,520 --> 00:21:08,160
but their temperature is now
dangerously low.
265
00:21:13,120 --> 00:21:14,960
But basking will re-warm them
266
00:21:14,960 --> 00:21:18,400
and aid in the digesting
of that algae meal.
267
00:21:21,440 --> 00:21:23,600
Every day they walk this
temperature tightrope.
268
00:21:28,360 --> 00:21:30,880
It's a remarkable lifestyle
that's evolved over millennia.
269
00:21:33,080 --> 00:21:36,440
Their reliance on a single
resource can be very productive,
270
00:21:36,440 --> 00:21:39,240
but also very precarious.
271
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The dependency of creatures
on the cool water currents
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00:21:45,600 --> 00:21:48,240
comes sharply into focus
273
00:21:48,240 --> 00:21:52,200
when that life-giving current
is switched off.
274
00:21:54,680 --> 00:21:58,120
And when it is, the results
can appear catastrophic.
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00:21:59,920 --> 00:22:02,040
Every three to six years,
276
00:22:02,040 --> 00:22:05,920
the seas around Galapagos undergo
a dramatic change.
277
00:22:08,640 --> 00:22:10,640
Pacific trade winds slacken
278
00:22:10,640 --> 00:22:14,000
and warm water shoots East
across the ocean.
279
00:22:17,760 --> 00:22:20,920
The blanket of warm water
engulfs Galapagos.
280
00:22:23,400 --> 00:22:27,600
It chokes off the cool life-giving
currents that feed the archipelago.
281
00:22:29,800 --> 00:22:33,040
And the marine food chain collapses.
282
00:22:36,400 --> 00:22:39,160
This is El Nino,
283
00:22:39,160 --> 00:22:42,160
one of the most destructive
weather systems on Earth.
284
00:22:47,400 --> 00:22:48,920
Its position on the equator
285
00:22:48,920 --> 00:22:51,520
means that Galapagos is right
in the line of fire
286
00:22:51,520 --> 00:22:56,480
and gets more and stronger
El Nino events than anywhere else.
287
00:22:59,880 --> 00:23:03,200
For creatures linked to the land,
isolated on these islands,
288
00:23:03,200 --> 00:23:05,720
there is nowhere to go
when El Nino hits.
289
00:23:13,920 --> 00:23:15,840
The El Nino of 1982
290
00:23:15,840 --> 00:23:18,400
was the most extreme in 400 years.
291
00:23:21,720 --> 00:23:24,840
Populations of animals
were decimated.
292
00:23:29,640 --> 00:23:32,480
El Nino creates a seesaw
of productivity
293
00:23:32,480 --> 00:23:35,280
for a number of years
every time it hits.
294
00:23:38,160 --> 00:23:41,240
But it's not all bad.
295
00:23:41,240 --> 00:23:44,240
The warm water creates
wetter weather,
296
00:23:44,240 --> 00:23:46,320
so, while the marine creatures
suffer,
297
00:23:46,320 --> 00:23:49,240
the land system goes into overdrive.
298
00:23:50,600 --> 00:23:53,800
There is an explosion of life
299
00:23:53,800 --> 00:23:56,840
and an increase in colonisation
between the islands.
300
00:24:00,320 --> 00:24:03,520
The seesaw then swings back.
301
00:24:03,520 --> 00:24:05,840
When cooler seas return,
302
00:24:05,840 --> 00:24:07,960
the marine system rebounds
303
00:24:07,960 --> 00:24:10,200
but the land system now suffers
304
00:24:10,200 --> 00:24:14,520
until normal conditions return.
305
00:24:14,520 --> 00:24:17,800
El Nino appears to be one of
nature's great destructive events.
306
00:24:20,240 --> 00:24:23,800
But El Nino also reveals
with great clarity
307
00:24:23,800 --> 00:24:27,200
the natural processes at work
in Galapagos.
308
00:24:29,360 --> 00:24:34,120
The stress El Nino creates
acts as a gruelling test
309
00:24:34,120 --> 00:24:38,160
in the race of survival
of the fittest.
310
00:24:38,160 --> 00:24:42,560
The individuals that do survive
thrive.
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00:24:46,200 --> 00:24:49,240
They and their offspring
flourish after the crisis.
312
00:24:53,160 --> 00:24:57,480
With less competition,
this becomes a land of opportunity.
313
00:24:57,480 --> 00:25:02,200
El Nino shows how crucial
the upwelling cool water is
314
00:25:02,200 --> 00:25:05,240
to feeding Galapagos.
315
00:25:06,760 --> 00:25:10,480
And it also shows how
profoundly the islands' isolation
316
00:25:10,480 --> 00:25:13,000
affects the resident creatures here.
317
00:25:15,840 --> 00:25:19,520
But there is a twist
in this tale of isolation,
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00:25:19,520 --> 00:25:23,240
a final key that unlocks a greater
understanding of the Galapagos.
319
00:25:25,040 --> 00:25:29,320
That key lies in how the archipelago
came to be in the first place.
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00:25:31,760 --> 00:25:34,240
For there is more to the unique
geological story
321
00:25:34,240 --> 00:25:37,120
and how that affects the creatures
here than many realise.
322
00:25:40,520 --> 00:25:43,080
The islands are born from
the Galapagos hotspot
323
00:25:43,080 --> 00:25:46,520
and are carried towards
the continent of South America,
324
00:25:46,520 --> 00:25:49,560
but they never get there.
325
00:25:49,560 --> 00:25:52,880
As the islands get carried
towards the mainland,
326
00:25:52,880 --> 00:25:56,840
the tectonic plate on which they sit
slides beneath the continent,
327
00:25:56,840 --> 00:25:59,080
taking the islands with it.
328
00:26:01,760 --> 00:26:03,360
Each island is born,
329
00:26:03,360 --> 00:26:06,440
lives
330
00:26:06,440 --> 00:26:10,680
and then disappears
on a conveyor belt of geology.
331
00:26:12,720 --> 00:26:17,440
The Galapagos conveyor belt has
created a geological treadmill,
332
00:26:17,440 --> 00:26:19,720
a continually changing home
333
00:26:19,720 --> 00:26:22,480
for the creatures that reside here.
334
00:26:26,480 --> 00:26:28,920
The archipelago may have existed
335
00:26:28,920 --> 00:26:32,600
for over 20 million years,
336
00:26:32,600 --> 00:26:35,120
but the oldest island we see today
337
00:26:35,120 --> 00:26:38,720
is only three million years old.
338
00:26:40,680 --> 00:26:44,240
Incredibly, marine iguanas
as a species
339
00:26:44,240 --> 00:26:49,120
are older than the islands
on which they live.
340
00:26:49,120 --> 00:26:51,720
Their ancestors arrived to islands
341
00:26:51,720 --> 00:26:55,120
that have since disappeared
beneath the waves.
342
00:26:57,440 --> 00:27:00,760
Their species has moved along
the geological treadmill,
343
00:27:00,760 --> 00:27:02,480
island hopping as it evolves.
344
00:27:06,840 --> 00:27:10,080
And this is the great revelation
of Galapagos,
345
00:27:10,080 --> 00:27:13,880
the reason for the creatures
and relationships
346
00:27:13,880 --> 00:27:15,880
that define this place.
347
00:27:17,920 --> 00:27:21,160
The volcanic conveyor belt has,
for millennia,
348
00:27:21,160 --> 00:27:25,040
created a truly
isolated archipelago.
349
00:27:25,040 --> 00:27:28,720
The isolation has forced the life
that managed to get here
350
00:27:28,720 --> 00:27:32,600
to have to continually adapt
and evolve.
351
00:27:35,000 --> 00:27:38,440
The upwelling currents
are the lifeblood of the system.
352
00:27:40,360 --> 00:27:42,360
They feed and sustain life.
353
00:27:46,320 --> 00:27:49,640
It's this combination
of the islands' unique geology
354
00:27:49,640 --> 00:27:53,640
and the upwelling currents
that makes Galapagos so special.
355
00:27:58,440 --> 00:28:00,840
Darwin saw in the Galapagos
356
00:28:00,840 --> 00:28:02,960
a "little world within itself"
357
00:28:02,960 --> 00:28:05,280
and, 170 years on,
358
00:28:05,280 --> 00:28:07,280
this still holds true.
359
00:28:10,920 --> 00:28:13,320
The islands that inspired
his groundbreaking theories
360
00:28:13,320 --> 00:28:16,440
continue to give us new insights
361
00:28:16,440 --> 00:28:21,400
into how Galapagos and all the
microworlds of our planet work.
29690
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