0:00:03 > 0:00:07Our Planet is the greatest living puzzle in the universe.
0:00:07 > 0:00:11A collection of worlds within worlds.
0:00:11 > 0:00:13Each one a self-contained ecosystem
0:00:13 > 0:00:14bursting with life.
0:00:18 > 0:00:20But how do they work?
0:00:22 > 0:00:25The intricate web of relationships
0:00:25 > 0:00:28and the influence of natural forces
0:00:28 > 0:00:33makes each microworld complex and unique.
0:00:34 > 0:00:37So, to discover their secrets,
0:00:37 > 0:00:41we need to explore them one by one.
0:00:41 > 0:00:44Untangle their interlocking pieces
0:00:44 > 0:00:48and ultimately reveal the vital piece,
0:00:48 > 0:00:50the key to life itself
0:00:50 > 0:00:55hidden deep within each of nature's microworlds.
0:01:06 > 0:01:08Galapagos is arguably
0:01:08 > 0:01:10the most pristine archipelago on Earth.
0:01:14 > 0:01:18It's a unique living world of truly enchanting islands.
0:01:25 > 0:01:27Nowhere else on our planet
0:01:27 > 0:01:31are the connections and dependencies within ecosystems so clear.
0:01:39 > 0:01:42Charles Darwin was the first to see this
0:01:42 > 0:01:45when he visited the islands over 170 years ago,
0:01:45 > 0:01:48but, as we will discover,
0:01:48 > 0:01:50he only saw part of the picture.
0:01:52 > 0:01:55What the makes the Galapagos so unique
0:01:55 > 0:01:57is that many of the creatures that live here
0:01:57 > 0:02:00are found nowhere else on Earth.
0:02:07 > 0:02:09Even more extraordinary is that there is life here at all
0:02:09 > 0:02:10Even more extraordinary is that there is life here at all
0:02:10 > 0:02:13on these barren, isolated islands.
0:02:16 > 0:02:18And what life!
0:02:21 > 0:02:23It's a bizarre collection of creatures...
0:02:27 > 0:02:30..from swimming lizards
0:02:30 > 0:02:33to tropical penguins
0:02:33 > 0:02:35and cormorants that can't fly.
0:02:39 > 0:02:42How has a place so harsh and isolated
0:02:42 > 0:02:44become a showcase for evolution
0:02:44 > 0:02:47and home to such a motley crew of creatures?
0:02:47 > 0:02:50And what is the pivotal piece
0:02:50 > 0:02:53that links all these animals to each other
0:02:53 > 0:02:55and to the islands they inhabit?
0:02:57 > 0:02:59To discover that,
0:02:59 > 0:03:02we must look at how these islands were created in the first place.
0:03:03 > 0:03:05Galapagos lies on the Equator,
0:03:05 > 0:03:08600 miles off the coast of Ecuador.
0:03:08 > 0:03:09600 miles off the coast of Ecuador.
0:03:09 > 0:03:11In this isolation lies part of the reason
0:03:11 > 0:03:14for the archipelago's unique wildlife.
0:03:17 > 0:03:19These islands are not a broken off piece of a continent.
0:03:19 > 0:03:22And they haven't been created from coral reefs
0:03:22 > 0:03:24like some other tropical archipelagos.
0:03:26 > 0:03:29This microworld has been born from forces deep within the Earth.
0:03:32 > 0:03:37Galapagos is one of the most volcanic places on the planet.
0:03:39 > 0:03:43And it regularly proves it with spectacular geological shows.
0:03:45 > 0:03:50The archipelago is plumbed into Earth's molten core.
0:03:53 > 0:03:58The islands have been created by a unique quirk of geology,
0:03:58 > 0:04:02known to scientists as the Galapagos hotspot.
0:04:02 > 0:04:06It's a thin part of the Earth's crust
0:04:06 > 0:04:10that periodically pushes up molten rock towards the surface.
0:04:10 > 0:04:15And the eruptions create islands.
0:04:16 > 0:04:18For 20 million years,
0:04:18 > 0:04:22the hotspot has continued to give birth to new land.
0:04:28 > 0:04:30As new islands form,
0:04:30 > 0:04:31they are carried away
0:04:31 > 0:04:33from the hotspot
0:04:33 > 0:04:34on shifting tectonic plates
0:04:34 > 0:04:35towards South America
0:04:35 > 0:04:37creating the string of islands
0:04:37 > 0:04:38we see today.
0:04:43 > 0:04:48This raw geology makes for a very tough place to live.
0:04:49 > 0:04:53And affects the bizarre creatures and relationships in Galapagos.
0:04:55 > 0:05:00But how did life get all the way out here in the first place?
0:05:03 > 0:05:06To colonise such remote islands,
0:05:06 > 0:05:09life would face many daunting challenges.
0:05:09 > 0:05:13To get here, any living thing would first have to cross 600 miles
0:05:13 > 0:05:17of open ocean from the nearest mainland.
0:05:17 > 0:05:21Plants are the first pioneers of any new landscape.
0:05:23 > 0:05:26Their seeds float here
0:05:26 > 0:05:28or are blown in,
0:05:28 > 0:05:32or they may be carried in the feathers or droppings of sea birds.
0:05:34 > 0:05:38Just getting here is a formidable challenge.
0:05:39 > 0:05:43Getting a foothold in the lava landscape is something else.
0:05:45 > 0:05:47But life finds a way.
0:05:50 > 0:05:54The whole terrestrial system is dependant on a few plants
0:05:54 > 0:05:56to kick start the colonisation.
0:05:57 > 0:06:00Mangroves are true ocean voyagers.
0:06:00 > 0:06:02Their seeds are tough enough
0:06:02 > 0:06:06to withstand the desiccating effect of months in salt water.
0:06:07 > 0:06:10Lava cactus pioneer the colonisation of the land.
0:06:16 > 0:06:21While Opuntia cactus open up the land still further.
0:06:22 > 0:06:24With so few species,
0:06:24 > 0:06:27the delicate dependencies between those species
0:06:27 > 0:06:29makes for some incredible relationships.
0:06:38 > 0:06:41Many of the native flowering plants in Galapagos are yellow.
0:06:46 > 0:06:49And that's because the only species of bee
0:06:49 > 0:06:52that's managed to make it here and pollinates the flowers
0:06:52 > 0:06:54is attracted to yellow.
0:06:54 > 0:06:57So there's little point in being anything else.
0:07:02 > 0:07:06The integrity of the food chain relies on the few insects
0:07:06 > 0:07:07pollinating the plants,
0:07:07 > 0:07:10because the next layer of creatures depend on them.
0:07:15 > 0:07:17Reptiles are a true hallmark of Galapagos,
0:07:17 > 0:07:22not necessarily because they deal better with the conditions here,
0:07:22 > 0:07:25but because they managed to get here in the first place.
0:07:27 > 0:07:30Reptiles are adept at surviving in salt water,
0:07:30 > 0:07:35so they stand a good chance of getting through a vast ocean crossing.
0:07:36 > 0:07:40Once here, they had to adapt to what's on offer
0:07:40 > 0:07:45and, in doing so, became the next integral layer of the ecosystem.
0:07:48 > 0:07:52Land iguanas rely on Opuntia cactus as their staple food.
0:07:56 > 0:07:58On the more barren islands,
0:07:58 > 0:08:00the shells of saddle back giant tortoises
0:08:00 > 0:08:05have evolved quirky shapes to allow them to stretch their necks upwards
0:08:05 > 0:08:07to higher, tasty cactus morsels.
0:08:10 > 0:08:13But the cactus also relies on the tortoise.
0:08:13 > 0:08:13They spread their seeds in their droppings as they roam the islands.
0:08:14 > 0:08:18They spread their seeds in their droppings as they roam the islands.
0:08:18 > 0:08:23At the top of the food chain, the surprising relationships continue.
0:08:23 > 0:08:28The top predator here isn't what you might expect.
0:08:28 > 0:08:31This is the Galapagos hawk.
0:08:36 > 0:08:38The challenge for a female hawk is to find enough food
0:08:38 > 0:08:41to raise her young in such a barren place.
0:08:41 > 0:08:43to raise her young in such a barren place.
0:08:43 > 0:08:46With next to no small mammals to hunt
0:08:46 > 0:08:50she turns her attention to what dominates the land here.
0:08:52 > 0:08:55Marine iguanas nest for only a few weeks each year.
0:08:59 > 0:09:02Which doesn't leave her much time.
0:09:09 > 0:09:11But she simply must succeed.
0:09:24 > 0:09:26One life ends...
0:09:30 > 0:09:31..and another begins.
0:09:37 > 0:09:39But there's another reason so many creatures here,
0:09:39 > 0:09:42like the Galapagos hawk, are endemic,
0:09:42 > 0:09:45found nowhere else on Earth.
0:09:50 > 0:09:54In Galapagos, we see unique species everywhere we look.
0:09:54 > 0:09:58Not just on land, but also at sea.
0:10:08 > 0:10:11Galapagos sea lions might look like any other sea lion.
0:10:11 > 0:10:14But the science proves otherwise.
0:10:15 > 0:10:16Their ancestors arrived here from California 2.5 million years ago,
0:10:16 > 0:10:20Their ancestors arrived here from California 2.5 million years ago,
0:10:20 > 0:10:22but they've continued to evolve here in isolation
0:10:22 > 0:10:24and are now so different
0:10:24 > 0:10:26they're considered a new species.
0:10:26 > 0:10:29Though they come ashore to breed,
0:10:29 > 0:10:31water is their natural environment
0:10:31 > 0:10:34and they depend on the richness of the seas.
0:10:38 > 0:10:40The flightless cormorant is a real Galapagos oddity
0:10:40 > 0:10:44and has evolved to suit a purely aquatic existence.
0:10:56 > 0:10:59With no real land predators to escape from,
0:10:59 > 0:11:01flight was of limited use.
0:11:03 > 0:11:07Under water their wings were actually a hindrance,
0:11:07 > 0:11:10and, over time, they dwindled to mere stubs.
0:11:10 > 0:11:12The entire species are now bound
0:11:12 > 0:11:16to a tiny stretch of the Galapagos coast.
0:11:16 > 0:11:19Even some creatures that can easily leave the islands
0:11:19 > 0:11:22are also considered endemic.
0:11:22 > 0:11:25Like the waved albatross.
0:11:25 > 0:11:27After months fishing further out at sea,
0:11:27 > 0:11:29the first touchdown isn't always graceful.
0:11:29 > 0:11:32the first touchdown isn't always graceful.
0:11:41 > 0:11:4395% of the world's population
0:11:43 > 0:11:47return to just one Galapagos island each year to breed.
0:11:51 > 0:11:53These birds mate for life.
0:11:53 > 0:11:56The first challenge is to find their partners.
0:11:56 > 0:12:01When they do, they rekindle their relationship with a delightful duet.
0:12:01 > 0:12:02THEY SQUAWK
0:12:02 > 0:12:07THEY SQUAWK
0:12:22 > 0:12:24Over the last few hundred years,
0:12:24 > 0:12:27the Galapagos has been seen as a living laboratory,
0:12:27 > 0:12:30helping us to understand
0:12:30 > 0:12:31how creatures specialise
0:12:31 > 0:12:34and evolve to suit their environment.
0:12:34 > 0:12:37There is one example, above all others,
0:12:37 > 0:12:40that reveals just that - Darwin's finches.
0:12:42 > 0:12:47Few terrestrial birds managed to make it to these isolated islands.
0:12:47 > 0:12:48The finches that did make it
0:12:48 > 0:12:51now fill all the various niches available.
0:12:55 > 0:12:58The finches share a common ancestor,
0:12:58 > 0:13:00but have evolved into many different forms
0:13:00 > 0:13:03to exploit their new habitats.
0:13:03 > 0:13:06Different finches each rely on different plants
0:13:06 > 0:13:09and creatures to make a living.
0:13:09 > 0:13:12They have evolved to take the place of woodpeckers.
0:13:12 > 0:13:15They've become tool users.
0:13:21 > 0:13:25Others have developed larger beaks for cracking seeds.
0:13:27 > 0:13:29They've even turned into vampires.
0:13:31 > 0:13:35These finches learnt that sea bird blood makes a nutritious meal,
0:13:35 > 0:13:37full of protein and minerals.
0:13:37 > 0:13:41These avian vampires don't kill their host,
0:13:41 > 0:13:44though the blood meal must surely weaken the larger bird.
0:13:46 > 0:13:51Galapagos finches are such a clear example of how creatures can evolve
0:13:51 > 0:13:55that Darwin eventually saw in these little birds
0:13:55 > 0:13:57the foundations for his big theories
0:13:57 > 0:14:01on evolution by natural selection.
0:14:03 > 0:14:05These would shock the world
0:14:05 > 0:14:08and revolutionise biology.
0:14:08 > 0:14:11But there is a further key to working out how all this life
0:14:11 > 0:14:15is interconnected and intrinsically linked to the islands.
0:14:17 > 0:14:21Something even Darwin didn't realise.
0:14:21 > 0:14:23To discover what that is,
0:14:23 > 0:14:26we must look to where island life concentrates -
0:14:26 > 0:14:28the coast.
0:14:29 > 0:14:33The community of coastal creatures is heavily interlinked
0:14:33 > 0:14:36and the dependency between them is clear to see.
0:14:40 > 0:14:45Sally Lightfoot crabs clean dead skin off the basking marine iguanas.
0:14:48 > 0:14:53Lava lizards also use the iguanas as lookout posts.
0:14:56 > 0:14:59These endemic animals are true opportunists.
0:15:01 > 0:15:03Any advantage here is worth taking.
0:15:05 > 0:15:07Sea lions become hunting grounds.
0:15:12 > 0:15:15It's a relationship that works for everyone.
0:15:15 > 0:15:17Well, except the fly.
0:15:23 > 0:15:28On the coast, we see creatures that depend on the land to breed.
0:15:34 > 0:15:34And on the seas to feed.
0:15:35 > 0:15:36And on the seas to feed.
0:16:01 > 0:16:03Their lives are linked to the sea.
0:16:09 > 0:16:12There is something special about the seas here
0:16:12 > 0:16:15that all coastal creatures rely on.
0:16:15 > 0:16:19And a clue to what that is can be found beneath the beds of lava.
0:16:22 > 0:16:27There is one seabird here that you'd never expect to find on the equator.
0:16:29 > 0:16:33The world's only tropical penguins.
0:16:34 > 0:16:38These lava tubes once flowed with molten magma.
0:16:38 > 0:16:40Now the penguins rely on them
0:16:40 > 0:16:45to hide their vulnerable chicks from the baking sun.
0:16:45 > 0:16:48But the real secret to how Galapagos penguins can survive here
0:16:48 > 0:16:51is down to something in the seas.
0:16:57 > 0:17:00Although the archipelago lies in the path
0:17:00 > 0:17:01of a number of warm water systems,
0:17:01 > 0:17:03Galapagos is also washed
0:17:03 > 0:17:06by a tongue of cold, Antarctic water
0:17:06 > 0:17:09called the Humboldt Current.
0:17:12 > 0:17:14The penguin's ancestors
0:17:14 > 0:17:19were brought to Galapagos by that cool Humboldt Current,
0:17:19 > 0:17:22and it continues to sustain the surviving population to this day.
0:17:29 > 0:17:32This cooler water holds more life-giving oxygen
0:17:32 > 0:17:36than warmer tropical waters that are typically found at this latitude.
0:17:38 > 0:17:43The cool water combines with the equatorial sun
0:17:43 > 0:17:45to feed the marine ecosystem.
0:17:45 > 0:17:50It makes for one of the most productive tropical marine environments in the world.
0:17:52 > 0:17:57All sea creatures depend on these life-giving currents.
0:17:57 > 0:18:02It's the reason the fish life so is rich,
0:18:02 > 0:18:04both in abundance and diversity.
0:18:12 > 0:18:16The volcanic character of the islands also plays its part.
0:18:23 > 0:18:25The flanks of the volcanoes draw cold water up
0:18:25 > 0:18:27from the deep ocean to the surface.
0:18:31 > 0:18:34It makes the seas around the youngest, most barren islands
0:18:34 > 0:18:38the most productive in the archipelago.
0:18:38 > 0:18:40And it is here that we find the largest communities
0:18:40 > 0:18:43of a truly bizarre creature
0:18:43 > 0:18:47that has evolved a lifestyle linked to the productivity of the seas.
0:18:50 > 0:18:53Galapagos Marine iguanas are the only sea-going lizard
0:18:53 > 0:18:55found in the whole world.
0:18:57 > 0:19:01The barren lava shore offers little to feed on,
0:19:01 > 0:19:05so it's not surprising that their terrestrial ancestors
0:19:05 > 0:19:08took to the rich waters to find food.
0:19:12 > 0:19:16What is astonishing is that they've evolved to eat only marine algae.
0:19:21 > 0:19:25But in doing this, the iguanas face a dilemma.
0:19:25 > 0:19:28They need the algae but it lies in cold water,
0:19:28 > 0:19:32a real problem for a cold-blooded creature.
0:19:34 > 0:19:38If they get too chilled, they become sluggish and eventually can't swim.
0:19:38 > 0:19:42So they need to offset periods of diving
0:19:42 > 0:19:46with time spent in strong equatorial sun.
0:19:46 > 0:19:51We can see how it works by looking at the iguanas in thermal imagery.
0:19:55 > 0:19:56As they bask, the lethal chill is driven away,
0:19:56 > 0:19:59As they bask, the lethal chill is driven away,
0:19:59 > 0:20:02giving them more energy to take the plunge again.
0:20:05 > 0:20:08By raising their temperature to 37 degrees centigrade,
0:20:08 > 0:20:12they buy themselves time.
0:20:12 > 0:20:14They can return to the cold water to find the algae.
0:20:17 > 0:20:22Smaller, younger individuals forage in the shallows.
0:20:22 > 0:20:26The larger individuals must dive deeper and for longer
0:20:26 > 0:20:30to tap the richer pastures that will sustain their greater size.
0:20:38 > 0:20:43Larger males can hold their breath for up to 30 minutes.
0:20:43 > 0:20:46But the clock is ticking.
0:20:49 > 0:20:55It is crucial to find food, feed and get out.
0:21:04 > 0:21:06They return to the safety of shore
0:21:06 > 0:21:08but their temperature is now dangerously low.
0:21:13 > 0:21:15But basking will re-warm them
0:21:15 > 0:21:18and aid in the digesting of that algae meal.
0:21:21 > 0:21:24Every day they walk this temperature tightrope.
0:21:28 > 0:21:31It's a remarkable lifestyle that's evolved over millennia.
0:21:33 > 0:21:37Their reliance on a single resource can be very productive,
0:21:37 > 0:21:39but also very precarious.
0:21:43 > 0:21:46The dependency of creatures on the cool water currents
0:21:46 > 0:21:48comes sharply into focus
0:21:48 > 0:21:52when that life-giving current is switched off.
0:21:55 > 0:21:58And when it is, the results can appear catastrophic.
0:22:00 > 0:22:02Every three to six years,
0:22:02 > 0:22:06the seas around Galapagos undergo a dramatic change.
0:22:09 > 0:22:11Pacific trade winds slacken
0:22:11 > 0:22:14and warm water shoots East across the ocean.
0:22:18 > 0:22:21The blanket of warm water engulfs Galapagos.
0:22:23 > 0:22:28It chokes off the cool life-giving currents that feed the archipelago.
0:22:30 > 0:22:33And the marine food chain collapses.
0:22:36 > 0:22:39This is El Nino,
0:22:39 > 0:22:42one of the most destructive weather systems on Earth.
0:22:48 > 0:22:49Its position on the equator
0:22:49 > 0:22:52means that Galapagos is right in the line of fire
0:22:52 > 0:22:57and gets more and stronger El Nino events than anywhere else.
0:23:00 > 0:23:03For creatures linked to the land, isolated on these islands,
0:23:03 > 0:23:06there is nowhere to go when El Nino hits.
0:23:14 > 0:23:16The El Nino of 1982
0:23:16 > 0:23:18was the most extreme in 400 years.
0:23:22 > 0:23:25Populations of animals were decimated.
0:23:30 > 0:23:33El Nino creates a seesaw of productivity
0:23:33 > 0:23:35for a number of years every time it hits.
0:23:38 > 0:23:41But it's not all bad.
0:23:41 > 0:23:44The warm water creates wetter weather,
0:23:44 > 0:23:46so, while the marine creatures suffer,
0:23:46 > 0:23:49the land system goes into overdrive.
0:23:51 > 0:23:54There is an explosion of life
0:23:54 > 0:23:57and an increase in colonisation between the islands.
0:24:00 > 0:24:04The seesaw then swings back.
0:24:04 > 0:24:06When cooler seas return,
0:24:06 > 0:24:08the marine system rebounds
0:24:08 > 0:24:10but the land system now suffers
0:24:10 > 0:24:15until normal conditions return.
0:24:15 > 0:24:18El Nino appears to be one of nature's great destructive events.
0:24:20 > 0:24:24But El Nino also reveals with great clarity
0:24:24 > 0:24:27the natural processes at work in Galapagos.
0:24:29 > 0:24:34The stress El Nino creates acts as a gruelling test
0:24:34 > 0:24:38in the race of survival of the fittest.
0:24:38 > 0:24:43The individuals that do survive thrive.
0:24:46 > 0:24:49They and their offspring flourish after the crisis.
0:24:53 > 0:24:58With less competition, this becomes a land of opportunity.
0:24:58 > 0:25:02El Nino shows how crucial the upwelling cool water is
0:25:02 > 0:25:05to feeding Galapagos.
0:25:07 > 0:25:11And it also shows how profoundly the islands' isolation
0:25:11 > 0:25:13affects the resident creatures here.
0:25:16 > 0:25:20But there is a twist in this tale of isolation,
0:25:20 > 0:25:23a final key that unlocks a greater understanding of the Galapagos.
0:25:25 > 0:25:29That key lies in how the archipelago came to be in the first place.
0:25:32 > 0:25:34For there is more to the unique geological story
0:25:34 > 0:25:37and how that affects the creatures here than many realise.
0:25:41 > 0:25:43The islands are born from the Galapagos hotspot
0:25:43 > 0:25:47and are carried towards the continent of South America,
0:25:47 > 0:25:50but they never get there.
0:25:50 > 0:25:53As the islands get carried towards the mainland,
0:25:53 > 0:25:57the tectonic plate on which they sit slides beneath the continent,
0:25:57 > 0:25:59taking the islands with it.
0:26:02 > 0:26:04Each island is born,
0:26:04 > 0:26:06lives
0:26:06 > 0:26:11and then disappears on a conveyor belt of geology.
0:26:13 > 0:26:14The Galapagos conveyor belt has created a geological treadmill,
0:26:14 > 0:26:18The Galapagos conveyor belt has created a geological treadmill,
0:26:18 > 0:26:20a continually changing home
0:26:20 > 0:26:23for the creatures that reside here.
0:26:27 > 0:26:29The archipelago may have existed
0:26:29 > 0:26:33for over 20 million years,
0:26:33 > 0:26:35but the oldest island we see today
0:26:35 > 0:26:39is only three million years old.
0:26:41 > 0:26:44Incredibly, marine iguanas as a species
0:26:44 > 0:26:49are older than the islands on which they live.
0:26:49 > 0:26:52Their ancestors arrived to islands
0:26:52 > 0:26:55that have since disappeared beneath the waves.
0:26:57 > 0:27:01Their species has moved along the geological treadmill,
0:27:01 > 0:27:03island hopping as it evolves.
0:27:07 > 0:27:10And this is the great revelation of Galapagos,
0:27:10 > 0:27:14the reason for the creatures and relationships
0:27:14 > 0:27:16that define this place.
0:27:18 > 0:27:21The volcanic conveyor belt has, for millennia,
0:27:21 > 0:27:25created a truly isolated archipelago.
0:27:25 > 0:27:29The isolation has forced the life that managed to get here
0:27:29 > 0:27:33to have to continually adapt and evolve.
0:27:35 > 0:27:38The upwelling currents are the lifeblood of the system.
0:27:40 > 0:27:42They feed and sustain life.
0:27:46 > 0:27:50It's this combination of the islands' unique geology
0:27:50 > 0:27:54and the upwelling currents that makes Galapagos so special.
0:27:59 > 0:28:01Darwin saw in the Galapagos
0:28:01 > 0:28:03a "little world within itself"
0:28:03 > 0:28:05and, 170 years on,
0:28:05 > 0:28:07this still holds true.
0:28:11 > 0:28:13The islands that inspired his groundbreaking theories
0:28:13 > 0:28:16continue to give us new insights
0:28:16 > 0:28:23into how Galapagos and all the microworlds of our planet work.
0:28:54 > 0:28:57Subtitles by Red Bee Media Ltd