Cauldron of Life Galapagos

In the vastness of the Pacific,

a once-in-a-lifetime expedition is underway.

For the next few weeks,

we are going on a voyage of discovery

covering over 1,000km through the Galapagos Islands.

Galapagos, one of the treasures of the natural world.

Over 1,000 species here are found nowhere else on earth,

and they've evolved in extraordinary ways.

But this paradise is under threat,

as our world is changing like never before.

Now we're embarking on one of the most ambitious

scientific expeditions ever attempted in Galapagos.

I'm Liz Bonnin, I'm a wild animal biologist helping to carry out

ground-breaking research in the field.

Joining me is a team of world-renowned scientists.

Equipped with cutting-edge technology,

we'll be able to study the wildlife of Galapagos up close

to see how it's adapting to change.

-How does that look?

-That's perfect.

'In its rich ocean.'

Orca pod just sighted.

There, right there.

'On its volcanic slopes.'

This volcano erupted this time last year.

'And within hidden worlds.'

This place is just incredible.

We'll attempt to help save animals on the brink of extinction.

Iguana! Iguana!

And dive into the unknown to discover species new to science.

This just changes everything.

Everything.

Oh, my God, look at this.

This is Mission Galapagos.

Combined, the Galapagos Islands cover an area just a tenth

the size of Scotland.

They lie in the Pacific,

1,000km from the coast of South America.

Galapagos is made up of 13 main islands

and many smaller rocky outcrops.

Sitting right on the equator,

these subtropical islands enjoy relatively consistent temperatures.

But this also makes them vulnerable to the rapid effects

of climate change.

And now these unique islands

are under greater threat than ever before.

It's why we've come here to study their animals and find ways

to protect them.

This is Alucia, a 56-metre research vessel - our base of operations.

An expedition like this on this sort of scale has never been attempted

in the Galapagos before.

Over the next few weeks, we'll be gaining unprecedented insights

into the wildlife here, with the help of the scientists

we're teaming up with.

This ship is a scientist's dream.

INDISTINCT RADIO COMMUNICATION

'And we'll be working alongside some of the best from both

'the Galapagos and across the world,

'all taking advantage of this unique opportunity.'

Charles Darwin visited the Galapagos almost 200 years ago

on a research expedition of his own.

He was just 26 years old at the time.

He began to recognise the process of evolution here,

which would inspire a theory that transformed the way we think

about all life on Earth.

On the first leg of this journey we'll be exploring the youngest

volcanic islands in the west of the Galapagos and investigating

the remarkable ways in which animals have adapted

to their hostile environments.

We'll be looking for the species that are most at risk,

to find out if they're adapting fast enough to survive.

Our first mission will be one of the most ambitious of all.

It will take us to the very top of the active Wolf Volcano.

In this extreme location, we'll be looking

for one of the most recently discovered and rarest species.

Weather conditions around the volcano are so changeable

that, if we get it wrong, we'll be stranded.

Our helicopter pilot, Tyler, isn't taking any chances.

Something that we take very seriously is getting someone

up there and then not being able to pull them back off the mountain

for potentially days,

and, so, we've briefed the team to bring shelter,

bring enough food to last a day or two just in case the weather

moves in and we can't get back to you.

-PILOT:

-We're currently at a course of 000,

speed 11 knots through the water.

The volcano towers over the northern part of Isabela,

the largest island in Galapagos.

Wolf is one of six volcanoes which erupted and joined together

to form this island over the past million years.

Seeing it for the first time is breathtaking.

There it is, Wolf Volcano.

Sitting above the clouds.

It's the tallest volcano in the Galapagos - 1,700 metres.

It's one of the least explored, most pristine parts

of the archipelago, and it's home to a reptile

that only a few people have ever seen in the flesh -

the pink iguana.

It wasn't until 2009 that the pink iguana was first identified

as a new species, and scientists think that only around 200 remain.

It's thought they once lived all across the Galapagos Islands,

but, slowly, this species has been dying out.

It's hard to believe that Wolf Volcano is now the only place

on Earth that they exist.

And, up here, everything can change in the blink of an eye.

All of this lava flow is very, very young.

This volcano erupted this time last year.

We are camping on the other side,

which I'm told is the inactive side of a volcano.

But, like all good volcanoes,

you don't ever know exactly where or when it's going to erupt next.

The 2015 eruption shook the scientific community.

Over half the volcano's crater was covered in lava,

wiping out every living thing in its path.

So, assessing how many pink iguanas are left is vital.

But, first, we have to find them.

A few days ago, our team of scientists headed up in advance

to drop off equipment and set up camp.

Now I'm joining them.

Evolutionary biologist and team leader Dr Gabriele Gentile

is here to meet me.

-Gabriele!

-Hello, Liz.

-How are you?

I'm pretty good, how about you?

Really well. What a flight in. That was extraordinary.

-Welcome here.

-How are things in camp?

-Good.

-Shall we get some coffee going?

-Let's get some coffee.

Hola, everybody.

Hello, hello, hello.

'Gabriele and his team identified the pink iguana as a new species.

'So, if anybody can find one, it's them.'

This is what we'll be doing today. We'll start from the camp,

then we'll walk along the rim of the crater.

We have to proceed very slowly and try not to be very loud

cos iguanas, they'll run away.

Very important is that any of us that will see an iguana just say,

"Hey, iguana," and we'll start our procedure to capture them

and then collecting data.

-Bueno?

-Bueno.

Good, good, good. Can I have an almond?

No.

LAUGHTER

Understanding as much as possible about the pink iguana,

how they live, what they eat, when they breed,

is the only way for scientists to learn how to protect them.

The search is on.

This is mind-blowing, Gabriele.

-Yeah, it's beautiful.

-I know we're on a mission but can I just

take two seconds? I need to take this in.

-Take your time.

-Wow.

It's not long before we spot the first clues -

the burrows these reptiles use for nesting and shelter.

Big hole over here.

Burrows everywhere.

We have to be really careful not to stand near the burrow

otherwise we'll just collapse the whole thing.

They're quite delicate.

There's another one. Just be really careful.

After hiking for hours,

it's becoming clear that finding a pink iguana really isn't that easy.

Look at the size of Wolf Volcano.

And there are about 200 pink iguanas that scientists need to find

in order to protect them.

Iguana!

Iguana!

We've got a pink iguana. It's a new one.

-It's big.

-It is. It's a big male.

Oh, my God.

It's a huge male.

-Look at that.

-All right.

Well done.

It's a big one.

He is such a beautiful specimen.

He looks really healthy.

He actually is in good shape.

There's not much food now in this area

-but he's doing good.

-Yeah.

Once found across the island chain,

over thousands of years and due in part to competition from

another iguana species, Wolf has become their last stronghold.

-So, Gabriele, I presume you have to work really quickly.

-Yeah.

71.

HE SPEAKS IN SPANISH

So, now we measure this animal.

Measuring size and weight will indicate if it's getting

enough food and growing normally. Blood tests will show hormone levels

and any signs of disease.

This data will tell the team if the last remaining pink iguanas

are healthy.

To set eyes on a pink iguana...

..is an honour, actually.

It's a real honour. And he's beautiful.

He's a stunning male.

Look at that.

This colour is not due to the presence of pigment but is actually

blood flowing in the deeper layer of the skin.

So they're pink but not because of pink pigment.

They're pink because they have no pigmentation.

That's correct.

Given the fact that you're taking so many measurements

from this individual alone,

is that indicative of how little we know about pink iguanas?

Well, we collect all the data because they may be informative

about the ecology and evolution of the species,

because there are so few individuals left.

Scientists still don't fully understand why so few pink iguanas

survive, and whether this tiny population can ever recover.

But this research will go a long way towards gaining more knowledge

about this precious reptile.

So, there we go. He's marked him on his body.

The paint is harmless,

but will allow Gabriele to identify this animal.

Are we letting him go now?

-Yeah, we're letting him go.

-And to think that they're...

..just hanging on by a thread.

I love the fact that it was done quickly, calmly,

minimum stress to the animal,

get your measurements done and then off you go.

Gabriele can use the data he's gathered to explore a new plan,

to move some of the iguanas to another part of Galapagos

and establish a second healthy population.

There will be chances for this species to survive,

especially continuing to input all these efforts.

To give the pink iguana a chance somewhere else.

Another spot to live.

But for this to have success,

we need to learn a lot about the ecology of the species.

There are so few left in just this one place.

Are we watching it on its way out,

as part of the natural process of evolution?

So, we have to consider extinction like a natural process as well,

but what a loss would that be.

Dinner time.

Chicken soup.

Thank you. Gracias.

Oh, yum.

Really, really good day.

It's just amazing to be out in nature like this.

You feel really alive.

The story of how the pink iguana ended up

on a remote volcano on the equator,

and somehow managed to make it here is ultimately a story of survival.

And stories like these abound here.

They're what make the Galapagos such a unique and special place.

Next morning, I head back to the Alucia,

leaving Gabriele and his team to search for more pink iguanas

during their final days here.

From a recently-discovered species at the top of a volcano,

it's time for me to descend down the side of one,

in search of new species on the sea floor.

'A mission that's only possible thanks to Alucia's most impressive

'pieces of technology.'

Two deep sea submersibles,

each capable of descending 1km beneath the waves.

'Leading this search is our expedition's marine biologist,

'Dr Pelayo Salinas de Leon.'

We're very excited about this dive.

It's the first time I'll be down to 1,000 metres.

And we're basically collecting as many weird-looking,

odd creatures that we encounter.

Pretty much everything that we see is very likely to be a new species

to science.

Our mission is taking us to a place no-one has gone before.

And we're in the safe hands of our submersible pilot Buck Taylor,

a veteran with over 2,000 dives under his belt.

It's such a harsh environment.

We're down at 1,000 metres, 3,300 feet.

Everything wants to crush us.

The pressure outside is huge.

So we've got to make sure every single system on the sub is working,

and working perfectly before we go anywhere near the water.

Come to starboard.

Come to port.

It's time for a final briefing in mission control.

Alucia's technical officer, Victor,

has been busy scanning the sea floor here to create 3-D maps of the area

we're hoping to explore.

So, how deep is it at its deepest point?

The area that we actually scanned is 1,550 metres.

OK. So, obviously, depth is important but then there's more

to it than just going deep, isn't there? What are we looking for?

We'll be looking at the green, which is around 1,000 metres.

And we'll be looking at this sort of shape.

So, the craggy bits, not the smooth slopes.

-Why?

-Because the craggy means very steep.

That's the perfect environment for animals to grow.

So, all these ridges are prime real estate.

So, that's what we're looking for - all the critters on the edge.

But does it make it more difficult to get to those areas?

Yes, sometimes.

We've got to approach with caution.

It could all change, you know.

Overhangs, ridges,

gullies and we get these local little anomalies with currents

and things, where it'll start rushing over an edge.

So, it'll start pushing the sub around, and it keeps us on our toes.

OK. You say the whole thing with a massive grin on your face.

-Cos it's fun.

-It's not a nervous grin, is it?

-No.

-OK.

I'm with Buck and Pelayo in the yellow three-seater sub, Nadir.

The smaller Deep Rover is our support sub, piloted by Toby.

Deep Rover will collect the samples for us and, at 1,000 metres,

is also an essential safety sub.

-Welcome to Nadir.

-Thank you.

INDISTINCT RADIO COMMUNICATION

Nadir, safety brief complete, ready to charge.

Roger. Shut your hatches.

-Both happy?

-Yeah, really happy.

-'As soon as they're ready.'

-Understood.

OK, moving off down the trolley.

All of Alucia's crew are now focused

on getting our eight-tonne submersible safely on its way.

-Wow.

-Here we go.

1,000 metres underneath us.

-Piece of cake.

-Piece of cake.

What's this for? For when I cry?

Yes.

OK. Bring it up.

That's the Nadir off-deck.

Nadir, ready to go.

Roger.

Bye-bye, surface.

In the Alucia's mission control room, surface officer, Alan,

will be tracking our progress every step of the way.

We've had a really successful launch.

At the moment, we can track them on sonar and we get very,

very good comms.

They've just reported in. Conditions are good.

VOICE FROM NADIR

As you can hear, they're talking between themselves.

So, we basically free-fall into the depths.

What speed are we descending at?

We try and do about one metre every four seconds.

At 200 metres, the light begins to disappear.

Below us is over 1,000 metres of deep sea.

This is the biggest ecosystem on earth.

It's also the most unexplored.

Control, control, Nadir passing 250 metres, over.

I feel like I'm in space.

It's better than space because there is life here.

It's sad that we do know more about the moon than we know about this.

And there's going to be critters going extinct that we've never

even discovered yet.

'We descend through clouds of zooplankton.

'Many of these tiny animals are invisible to the naked eye,

'but they're the lifeblood of these oceans.'

Just this is really breathtaking.

Because this is the reason why everything in the Galapagos

is so biodiverse and thriving.

It's all to do with this.

This soupy mix of all sorts of strange-shaped organisms.

'Zooplankton feeds a huge variety of sea life,

'and kick-starts the entire marine food web.'

You know, you're on the surface looking at all these charismatic,

big, beautiful animals but actually this is more awe-inspiring

and actually more humbling, in a way.

-Yes.

-If it wasn't for this, none of it would exist.

'We head towards our target depth.

'It's pitch-black down here and we're reliant on assistance

'from the surface.

'Nearing the jagged rocks,

'this can be the most dangerous stage of the dive.'

Nadir, Nadir, this is control, over.

As you can see, the subs are here at the moment, both together.

That area between the 50 metre, 80 metre and getting to 150 metres

off the bottom, we have to guide them.

'Until we can see the rocks, we're in their hands.

'Then, from out of the darkness, the flank of the volcano appears.'

Wow.

What is all this stuff?

Are they corals?

Control, control, Nadir.

Visibility lights on. 15 metres. Lights off, zero.

Bottom composition - rock and some sediment.

Tidal stream, we've got a slight...

'Two hours into the dive, we reach our target depth.'

1,000 metres, everybody.

So, there's five of us down here in the subs,

and there's only five people ever seen this. Ever.

'This is the deepest anyone has ever been in the Galapagos Islands.'

Just as we looked up at the screen, we knew they were close.

They are at 1,000 metres. So they're not interested in telling us,

or anything like that, they're just getting on with the job.

'Control, Nadir, depth 1,000 metres with the Rover.

-'Over.'

-As we hear, they've thought about us now,

and they've told us that they're 1,000 metres, you know.

So, that's nice that we know they're safe, they're happy.

How does it feel to be our modern-day, deep-sea Darwin?

-A lot of pressure?

-It's a lot of pressure,

but I prepared all my life for this.

I love it. I love it.

Over a kilometre beneath the waves,

the mission is now to ascend up the volcano wall to find and collect

new species.

This is basically the flank of a volcano.

Yes.

We're climbing a volcano.

Soon, a remarkable fish decides to pay us a visit.

A Galapagos ghost shark, or chimaera.

Oh, my God, he's awesome.

A fish discovered relatively recently, but it's been around

for at least 300 million years -

long before the dinosaurs.

If you look at them, it's kind of a mix between a ray and a shark.

Yes.

Chimaeras can live for up to 30 years.

Using their incredible sense of smell,

they hunt for shellfish in the dark,

grinding them up with tooth plates instead of rows of teeth.

Those enormous eyes work hard to take advantage of any light

that reaches the deep sea.

Starfish.

Oh, yeah, I think you're right.

I haven't seen that guy before.

Pelayo can only confirm a new species

if he takes a sample to study.

With a special permit from the Galapagos National Park,

he's one of the only people with the authority to do this.

For everything he collects and stores in these tanks,

he carefully records every detail about the habitat it came from.

It may appear invasive,

but taking these samples will help scientists to understand

how to better protect species in the deep sea.

Despite the fact that we're aware of how much we take from the planet,

-these samples are very important, aren't they?

-Yeah.

People only care about what they know and from here we know nothing.

Then something else catches Pelayo's eye -

a soft coral he's never seen before.

Move on, Pelayo?

No. Can we get Toby to grab that one?

This guy here, this soft coral.

I've got another sample for you, Toby.

Our search continues as we make our way up the slope.

Until another creature of the deep makes an appearance

and steals the show.

Pelayo thinks it is a type of deep-sea warty octopus,

and it's never been recorded in the Galapagos before.

She's carrying eggs

and will guard them for up to four and a half years,

longer than any other animal on the planet.

Our time in the abyss has come to an end.

Here we go, kids.

35 metres to go.

-Is that it? We're back in the real world.

-Nearly there.

Welcome back, everybody.

-Wow.

-Hello, Galapagos.

That experience...

..is probably the most exhilarating thing I will ever do

in my entire life.

That has trumped, officially trumped,

anything I've done in my entire life, personal and professional.

And you really did say, you know, "It'll fly by".

And I was like, "Yeah, but it's seven hours".

It flew by.

So our job isn't done for the day.

Because now we've all these amazing samples to take a look at.

In the ship's wet lab, Pelayo quickly begins to analyse

everything he's collected today - 16 samples in total.

So we're going to start with the first sample, which is this star

we collected at 1,000 metres deep.

So is this a specimen that you're familiar with?

No. When we were down there, it was the first time we saw this.

We take a small sample for genetic analysis.

DNA tests that can only be carried out on land will confirm

if these are indeed new species.

The process will take months,

but Pelayo is confident that what we've found

on these submerged volcanic slopes is new to science.

If so, it means scientists will be one step closer to unravelling

the mysteries of life in the deep.

We're a funny old species. We want to explore new frontiers,

we want to find out if there's life on Mars,

which in itself is hugely important,

and yet we've forgotten about this vast ocean that covers

the majority of our planet.

And for kilometres, down there,

there is stuff just waiting to be discovered.

While we've been exploring the deep,

Alucia's mission control has been continuing to scan the sea floor.

These 3-D maps show that Galapagos is littered

with underwater volcanoes known as seamounts.

Mission geologist Karen Harpp thinks some seamounts might explain

how certain species dispersed across the island chain,

adapting to each new environment they encountered.

That seamount's really interesting to us because it has a structure,

a shape that's not typical.

-It looks very flat.

-It is very flat.

You need therefore a way to explain why it has such a flat top,

and one of those ways is this notion that it is actually a sunken island.

As this volcanic island slowly sank beneath the ocean,

waves would have eroded down its peak into this flat shape.

What you see when you look at the Galapagos today is only its current

configuration. But if you go back even a half a million years,

one million years, two million years,

it turns out that very different islands were in different places,

and we have to think of it as a very dynamic place.

Which it surely is.

So why is the presence of a drowned island important,

with respect to our understanding of how animals might have

dispersed from island to island?

The way to think of it is as stepping stones.

If you can shorten the distance between two islands, you increase

the chances of a species getting relocated to that new island.

Many species most likely floated to Galapagos by chance and once here,

this island-hopping theory could explain how they were able to spread

across the archipelago to even its farthest reaches.

It's how the pink iguana could have made it

to one of its most remote volcanoes.

And how another iconic species can be found across most of Galapagos -

the giant tortoise.

Today, the largest population lives on Alcedo,

a volcano whose enormous crater, known as a caldera,

is rarely visited because it is so difficult to reach.

It's where we're heading next.

The expedition will be led by Pablo Valladares,

a guide working with the Galapagos National Park.

Alcedo has been hit by a drought this year,

and many scientists predict that they'll only become more severe

with climate change.

Pablo doesn't know how badly the giant tortoises have been affected.

One way to find out is to assess how well they're breeding.

This is it - the Alcedo Volcano.

Its caldera measures 6.4km in width.

And there you can see plumes of volcanic gas.

This volcano is still very much alive and active.

We need to find a nice population of tortoises.

How many tortoises are usually around this area, though?

Well, on Alcedo there is an estimate of between

5,000 and 8,000 tortoises.

Generally, when you get a mud pond, a wet area,

that's where all of them congregate.

So there's no mud ponds anywhere here, is there?

It has been very dry.

We head off in search of tortoises.

Look at this, Liz - we're following a tortoise path.

By generation and generation, tortoises have been walking,

they've been walking, following on this path.

You can see all the tracks of their feet and their bodies.

Darwin himself noticed these well-worn tracks

littering the landscape and that following them was the best chance

of finding fresh water.

Today, they lead us to a group of giant tortoises.

On a day like today, this is exactly what reptiles need to be doing.

They can't regulate their own body temperature like we can

and it would be very silly of them to hang out in this 32-degree heat.

So they're all huddled along what little shade they can find,

all along this tortoise track.

There's two here, there's two there, there's one over there.

They really are magnificent primordial beasts.

The Galapagos tortoise is one of the most long-lived creatures on Earth,

with an average lifespan of 100 years.

And they can weigh almost half a tonne, as much as five grown men.

These gargantuan reptiles can survive for up to a year

without any food or water.

That has got to go a long way towards helping them to succeed

in a challenging environment like this one.

But are they breeding?

Pablo soon finds evidence.

These are tortoise nests.

Look at all the shells, look.

This is amazing.

It's amazing. So this means tortoises are nesting here

and babies are hatching out.

This is the perfect spot for that because it is open,

so it'll allow the sun rays to go through and warm up the nests.

How many eggs do they lay at a time?

There's an average of ten eggs, generally,

and it depends on the tortoise population.

Babies will never meet their mother.

Or, if they do, they'll never know,

because the female closes the nest and goes.

They're on their own from the minute they hatch.

Absolutely. It gives you hope.

These are excellent signs that the tortoises are breeding.

They're having babies.

The hatchlings are nowhere to be seen, which is to be expected.

The first stage of the giant tortoise's life is known

as the lost years, as very little is known about them.

With Galapagos hawks circling overhead,

young tortoises need to remain hidden for several years

until they're large enough to fend for themselves.

It's an effective strategy that's contributed to their success here

for millions of years.

But with ever more severe droughts,

new challenges will be pushing their survival strategies to the limit.

Across the Galapagos,

tortoises have evolved to suit their habitat perfectly.

On the islands thick with vegetation,

their dome-shaped shells help them to plough through the undergrowth.

On more arid islands, where food is less plentiful,

their shells are saddle-shaped, with a peak at the front,

allowing them to reach the fruit of tall cacti.

Each tortoise is beautifully adapted to the island it came to inhabit,

resulting in 11 different types of Galapagos tortoise today.

But why are the environments across this small group of islands

so varied?

The answer can be found deep inside the Earth,

beneath this giant plate of rock on which the Galapagos sits.

Below Alcedo is a hot spot where magma wells up,

producing active volcanoes at the surface.

But these islands sit on a tectonic plate that moves slowly

over the hot spot.

Like a conveyor belt,

the newly-formed volcanic islands are pulled away from the hot spot

and, over time, they become inactive.

This island is drifting across the Earth's surface at a rate

of about seven centimetres a year.

The tectonic plate is carrying it, and the entire archipelago,

in that direction, towards the south-east.

It may not sound like much,

but in the 700,000 years since Isabela first formed,

it has moved 50km from its birthplace.

In just a few million years, as they travel away from the hot spot,

the islands transform from active volcanoes of barren rock,

to landscapes filled with lush vegetation,

covered in mist and cloud,

until, finally, they sink beneath the waves.

This is the reason why each Galapagos island

is so dramatically different to the next,

and why each island's inhabitants have had to adapt

in really specific ways in order to survive on them,

ending up completely different to their counterparts on other islands.

The wildlife of the Galapagos is a product of this dynamic,

ever-changing landscape.

This cycle of island birth and death has forced species here

to evolve and survive, or die.

The focus of our final mission...

..is an animal that's hard to miss

along the island's coastline.

The marine iguana.

When Darwin first encountered them, he was both fascinated and repulsed,

describing them as, "imps of darkness."

This unusual habit of sneezing salt...

..surely contributed to this reputation.

I am keen to have an encounter with these fascinating reptiles.

To see them in their element, I'm going to dive with them.

These are the world's only seagoing lizards.

Down here, you can see just how much they've changed

over millions of years, compared to their land ancestors...

..and why Darwin was interested in their remarkable adaptations

to the marine environment.

The largest individuals can hold their breath for over an hour.

They've developed strong, hooked claws to cling to the rocks...

..and blunt snouts full of razor-sharp teeth

to graze on the only food they eat - algae.

But every few years, this precious food source disappears,

proving catastrophic for the marine iguanas.

Our mission is to study how these extraordinary animals are adapting

to this threat.

To do this, we've brought our lab with us

to carry out a ground-breaking experiment in the field.

Professor Greg Lewbart is a wild animal vet.

The marine iguana has been his focus for the last three years.

It's such a unique animal.

The marine iguana can be sort of an indicator species

to the overall health of the islands.

Every few years, a major weather event, El Nino, hits Galapagos...

..and many scientists think they're getting stronger

with climate change.

During an El Nino, marine nutrient levels drop and the algae dies,

directly impacting on marine iguana numbers.

In 1983, 60% of marine iguanas were lost across the Galapagos.

In 1998, 90% of them died on some islands.

Marine iguana populations here take a regular beating.

Greg has been tracking individual marine iguanas and measuring them.

He's observed something extraordinary.

It appears that they're actually, at least some of them,

are getting shorter in order to survive El Nino events.

If you're smaller, you're going to need less food,

you're going to expend less energy,

and your odds of surviving are going to be significantly better.

We're not talking about animals that are just getting smaller

in terms of their size, like someone who loses weight.

-Right.

-They're actually shortening,

and that's really unheard of

in animals with backbones.

In addition to being able to shrink, they can grow again.

OK, so when you're talking about shrinking,

you don't mean generation on generation.

You mean individual iguanas, in their lifetimes,

are getting longer and shorter.

Yes. Kind of like an accordion.

So like a lizard accordion. I know, it's hard to comprehend.

To explore how these iguanas alter their size so dramatically,

we're going to do something that's never been attempted before.

We're X-raying the iguanas with this cutting-edge portable machine.

No-one has ever radiographed marine iguanas in the field like this.

So the iguana sits here.

-Yes.

-This takes the X-ray.

Does the iguana not try to scurry off the plate?

Well, no-one has ever done this before, so we're not sure.

OK, but step one is to catch them off those slippery rocks by the sea.

-Yes.

-Whose job is that, everybody's?

-That's the fun part.

-OK!

You got one?

-Hey.

-Fantastic.

It's a perfect, perfect first iguana for this.

How much can they tolerate handling before we need to release them?

-Quite a bit.

-Yeah?

You'll see that these animals are really pretty relaxed.

Some animals, when you put them on their back, they go into a trance.

So chickens do this, alligators do this,

-and fortunately marine iguanas do this.

-I love it.

It's a behaviour that Darwin first identified -

animals playing dead to discourage predators.

It's 78.3.

These heavy, lead overalls are a little cumbersome for the beach,

but they're designed to protect us from the X-rays.

-This is extra large.

-What are you saying?

So you got the medium and I get the extra large? I'm not going to take it personally, I'm not. It's fine.

-Oh, it is heavy.

-Yes. Now, go, turn around.

-Are you ready, Andy?

-Yes, I am ready.

You better be a good iguana.

I'm not going to try to do any restraint on him, OK, Andy?

-Are you ready?

-Yes, I'm ready.

One, two, three.

MACHINE BEEPS

Done.

-Good catch.

-Got you.

How does that feel?

It feels great. We've been wanting to do this for a couple of years,

and we've been dreaming about it.

By X-raying the skeletons of these iguanas,

Greg will be able to confirm how they achieve

this incredible transformation.

His plan is to return and X-ray the same individuals,

and by comparing the data,

he'll be able to see how these reptiles might break down

and rebuild bone tissue.

-Ready for release?

-All right, buddy.

You picked a great one. You got a good one.

He was really well behaved.

This research is revealing just how quickly these animals

are responding to challenges.

Who knows? If they survive to the next El Nino,

we're pretty sure they could shrink again.

Marine iguanas have not only been evolving over millennia,

they're capable of adapting to change in just a few months.

To me, it's like a magic trick.

I bet Darwin didn't know that iguanas were shrinking,

but he wasn't here long enough.

I'm astounded by the number of ways marine iguanas have adapted

to everything these islands have thrown at them,

ever since their ancestors arrived here millions of years ago,

by chance, on floating rafts of vegetation.

And, for me, they represent what the Galapagos is all about.

Our journey so far has revealed how this dynamic island chain

continues to shape the extraordinary wildlife here.

And how animals are adapting to change,

no matter how challenging the circumstances.

'Next time on Mission Galapagos,

'we'll dive into some of the most shark-infested waters on the planet,

'to discover why hammerheads congregate here

'in such huge numbers.'

Oh, my God, look at this.

LIZ YELLS

'We'll investigate how sea lions are faring

'in the face of climate change.'

I'm trying to keep up with him as he spins, spins, spins,

and I'm exhausted.

'Search for an elusive ocean giant,

'to find out what it gets up to in the deep.'

Coming right in.

GASPING Oh, my God.

'And experience the power of the Pacific,

'100 metres below the waves.'

Oh, God, that was close.