[intense music] - [Narrator] The greatest jungle on the planet.

Impenetrable, mysterious.

A tangle of myths and monsters.

There are trees that kill.

[pod thuds] Giant birds... [bird screeches] And big cats.

Even the little things are monstrous.

- Whoa.

- [Narrator] Welcome to the Amazon.

- I'd run.

I'd run as fast as I could.

- [Narrator] We're on two quests.

Hunting for a legendary creature... - Have you seen this?

Have you seen this?

Whoa.

[dramatic music] - [Narrator] And unraveling the workings of a biological machine.

[thunder rumbles] We'll end by unmasking the forest's biggest killer.

[trees cracking] [unnerving music] - [Presenter] This program was made possible by contributions to your PBS station from viewers like you.

Thank you.

[tense music] - [Narrator] This is the story of a giant tree, and the giant spider said to live in its shadow.

[wondrous music] The story unfolds in the biggest rainforest on the planet...

The Amazon.

The plants here pump out one fifth of the world's oxygen.

[wondrous music] The Amazon River holds a fifth of all the world's freshwater.

This place is an evolutionary powerhouse, generating literally millions of marvelous species.

[wondrous music] This may be the most important environment on our planet.

The giant of the Amazon is this tree, the Brazil nut.

[wondrous music] At 160 feet, it towers over the jungle.

Its famous nut is a global business worth 50 million dollars a year.

But at the center of the tree's life is a mystery.

If we can solve it, we may understand what drives the entire jungle ecosystem.

The mystery is this.

Why does this tree only produce its nut-filled pods in virgin rainforest?

If you damage the forest, the tree shuts down.

This makes the Amazon a very valuable place, and keeps loggers at bay.

[mysterious music] 21st century science is trying to understand the connection between this tree and the forest around it.

But the Brazil nut tree is not the jungle's only mystery.

[car honks] [mysterious music] In pursuit of very different quarry is Martin Nicholas.

He's tracking reports of a mythic beast, a giant spider unknown to science.

[tense music] His day job is selling water treatment systems, but in his spare time, he's a tropical spider expert.

- This is Puerto Maldonado, and it's got a real frontier town feel to it.

The town itself is built on gold and logging money, and it sits at the confluence between two of the great tributaries of the Amazon.

The Amazon River.

The Tambopata goes that way, the Madres Dios goes that way, and basically we're sitting right in the middle of primary rainforest, just with this town sitting in the middle of it.

- [Narrator] Like naturalists of old, Martin is heading into the dangerous unknown.

- One of the real hazards of working in an environment like this is the diseases that you do find in this area.

Our friend Artemio there, he has an appalling wasting condition called Leishmaniasis.

It causes huge scars.

It can affect any part of your body at all.

It is treatable in almost every case, although it can be fatal in extreme cases.

We're told that he got it somewhere up the Tambopata river, and guess where we're going?

[dogs barking] - [Narrator] Martin's journey was inspired by a letter from a friend in Peru.

- "I was talking to a farmer who tells me that he loses many of his chickens that live around his farm and that of his brother.

I asked if snakes or dogs are the predator, but he tells me it is the araña pollita, chicken spider, I think."

[chickens clucking] - [Narrator] He imagines the scene constantly.

This so-called "chicken-eating spider" is said to have legs as thick as a man's fingers.

[unnerving music] Martin's convinced he's looking for an unrecorded species of tarantula.

There are over eight hundred known kinds of tarantula, but none of them eats chickens.

[chicken squawks] [mysterious music] The idea of a spider that drags chickens round the backyards of Peru may sound absurd, but it's enough to drag an enthusiast like Martin half way across the globe.

[chicken squawks] - My gut reaction when I first got that letter was immediately, "I've got to go out and find it.

I've got to go out and have a look.

I've got to find the monster."

- [Narrator] Martin's quest is taking him deep into the Amazon, the largest piece of forest on earth.

85% of it hasn't been explored yet.

There may be tribes of indigenous people here who have no idea of what exists outside their forest.

This is still a lost world.

[daunting music] A world where a single tree contains complicated secrets.

To understand just how this jungle works, explorers are developing new kinds of high-tech jungle science.

[dramatic music] This is Barro Colorado Island in Panama, headquarters of The Smithsonian Tropical Research Institute.

t's a high-tech, outdoor laboratory.

[tense music] [creatures screeching] Scientists here use all the latest gizmos to discover how different animals and plants live their lives.

- This is probably within the last half hour to an hour, so it's getting really, really active.

[tense music] [camera shutters snapping] - It even looks as though the ocelot has taken a short rest immediately after the agouti line has gone flat.

[creatures screeching] - [Narrator] The experts discovered that the jungle is so complex it can only be understood by looking at it over tens, or even hundreds of years.

[tense music] So they started keeping small sections of rainforest under constant surveillance all over the world.

Nothing grows, nothing dies without it being recorded.

[tense wondrous music] Their data allows us to see years pass in seconds.

Huge changes are compressed into mere moments.

[tense wondrous music] To understand how a Brazil nut tree works, you need to look at its entire lifespan.

[tense wondrous music] This tree's life began 500 years ago as a nut inside a rock hard pod, just like this.

When it drops, it can kill.

[wondrous music] It's the weight of a cannonball, and accelerates to 50 miles an hour, in just three seconds.

[pod thuds] [intense music] The pod falling season can be a deadly lottery for the forest's animals.

[pod thuds] [intense music] [creatures screeching] The pod is a conundrum.

There's nothing in the Amazon with jaws strong enough to crush it, and release the seeds.

[pod thuds] This is the first problem in unraveling the tree's story.

It's led scientists in Peru to create an ingenious experiment.

[saw squeaks] It takes 20 minutes to saw open a pod.

A magnet is glued to each tagged nut, and the whole pod is put back together again.

These "trick" pods are then scattered around the forest.

They attract the solution to the problem.

The pod isn't opened by an animal with huge jaws at all, but a small rodent called the agouti, with teeth like chisels.

Amazingly, the Brazil nut tree depends entirely on this one species to release its seeds.

The agouti buries the nuts it doesn't eat, a future snack.

But they often forget where they've hidden them.

The forgotten nuts germinate into tiny trees.

[insects buzzing] By tracking the nuts with a metal detector, the experts found that the agoutis bury them in shade, often near the mother tree, and most kinds of seedlings die without strong, direct sunlight.

[metal detector beeps] But once again, Brazil nut is special.

In shady places, its seedlings can go dormant for decades.

The sapling of today's giant tree could have waited years, just like this, for something to change in the environment above.

[wondrous music] Back on the trail of the mystery spider, Martin Nicholas is following the best advice for travelers.

Always ask the locals.

- Arturo, my guide, knows of this little farm on the banks of the river that sounds exactly like the one mentioned in the letter that I got, so we're here to check it out, see if they know anything about these big, black spiders, and do a head count of the chickens as well.

[chickens clucking] Yes.

- [Speaker] That big.

- That's a big spider.

That's almost a foot across.

[Martin chuckles] Does he think that the big tarantula would be able to catch, say, one of the small chickens?

[people speaking Spanish] You think it could happen?

Yeah?

Anything is possible.

[chickens squawking] This is exactly the story that we've heard.

This is the tale that is now starting to reoccur.

Story from the letter, and we're obviously, definitely, in the right sort of place.

[dramatic music] - [Narrator] Martin heads deep into the jungle looking for the spider's lair.

[wondrous music] - Here's a spider.

Down here we have a ctenid spider, or wandering spider.

This one's quite a small one, and it's holding its egg sac in its jaws.

Obviously, this is the breeding season.

A bite from a spider of this sort of size probably wouldn't hurt, if indeed she could actually get her jaws through you in the first place.

The trick with most spiders in the world is that they cannot get their jaws wide enough open.

It's rather like us trying to bite into a beach ball, we can't... We can't get our mouths open wide enough.

And it's the same thing with spiders.

It's only the biggest spiders and the ones with the most powerful jaws that can actually get their jaws wide enough to penetrate our skin, and their jaws long enough to get through our skin, and then of those, very, very few have venom toxic enough to cause us any problem at all.

I don't think this little spider here would be considered dangerous at all.

- [Narrator] This forest hasn't always been wild and untamed.

Indigenous people once treated it like a kind of garden.

They planted Brazil nut trees in groves to make harvesting easier for their descendants.

But 500 years ago, when our giant tree was just a dormant sapling, terrible violence shook this Eden.

- It's incredible to think that these gigantic Brazil nut trees, 500 years ago, were just simply tiny little saplings.

But that they were to witness the most vicious and bloodthirsty war that this forest had ever seen, before and probably since.

- [Narrator] In 1532, Spanish conquistadors arrived.

[dogs barking] - They came here for one reason.

They came here for gold.

Unfortunately, the conquistadors thought that the indigenous people were subhuman.

They would torture them to death, just for the amusement of it.

They deliberately spread diseases.

They killed them in their thousands.

In their millions, actually.

[dog barks] [tense music] - [Narrator] The indigenous people were forced to fight for their very existence.

And in the end...

They were devastated.

Literally tens of millions died.

But ironically, the conquistadors may have breathed a spark of life into our dormant Brazil nut sapling, when they brought steel to the forest.

[dramatic music] [ax clangs] For the first time, the Amazon's great trees could be felled in minutes, rapidly creating great holes in the canopy above.

[dramatic music] [tree cracks] An event like this may have finally bathed our Brazil nut seedling in precious sunlight.

[tense music] Every fallen tree leaves a light gap.

As we see it, a gap looks unremarkable.

But to realize its full importance, we must speed up time.

[tense music] Now, the clearing explodes into life.

All kinds of plants join a race to keep ahead of each other, and avoid being left in the shade.

[tense music] Hungry animals exploit the fresh growth.

[tense music] [wondrous music] The Brazil nut sapling awakens.

[intense wondrous music] The tree grows into an unmistakable hallmark of the Amazon horizon.

[tree rumbles] Over the centuries, the Brazil nut becomes the center of a vast web of life, and scientists have come up with some ingenious ways of finding out what's in it.

A spray gun fires insecticide up into the canopy.

It knocks out insects, and they tumble back to earth in bewildering variety.

[creatures chirping] But which specific tree did the different insects fall from?

It's a tough question.

Time for a new idea.

[dramatic music] A hot air blimp carries a light-weight raft which scientists ride on.

Up here, they can pick out which trees they want to investigate.

[wondrous music] The raft is dropped right on top.

It used to be thought that there were about 3 million species of plants and animals on earth.

[Wondrous music] But work like this has made us revise the figure upwards to 20, 30, even 50 million.

[wondrous music] A single tree like the Brazil nut can hold thousands of different species.

[wondrous music] And this life isn't a random jumble.

These creatures form a web of relationships.

[lighthearted music] The tree's wilting flowers are not wasted.

These are leafcutter ants.

A single colony can hold ten million hungry individuals, so the seasonal shower of petals is a valuable bonus.

[lighthearted music] Where there are ants there are, of course, ant eaters.

The giant anteater has no teeth.

It slurps up its prey with a tongue over two feet long.

There are other ants here, and they're much more frightening.

- Whoa.

They say it's not the big things in the forest that get you.

It's not the jaguars or the lions or the tigers.

It's the little things, like the mosquitoes, and the sand flies.

And these are two of the biggest small things that get you.

They're called bullet ants, because the sting is reputed to feel very much like being shot.

Scary looking things, aren't they?

I know of a couple of people who've been stung by the bullet ant, and they say the pain is rather like, initially, rather like having a large cigar extinguished on your skin.

Incredible burning sensation.

There are some tribes in the Amazon that use bullet ants in their initiation ceremonies for their young men.

[mysterious traditional music] - [Narrator] The bullet ant's sting may be the most painful of any insect.

That's why it's become the test of manhood for the Sateré-Mawé.

200 ants are knocked out, and then woven sting-inwards into a glove.

When the ants come-to, they're very angry.

[dramatic music] Teenage boys must wear this for ten minutes while the ants inject their potent nerve toxin.

The test is to show no sign of pain.

[dramatic music] Their arms are paralyzed, and tremble uncontrollably for days.

[dramatic music] - I'm not going to put my finger anywhere near these.

I'm not being a wuss, it's just I don't want to be out for 24 hours.

- [Narrator] Martin's quest has brought him into the territory of the Amazon's big cat.

The Jaguar.

He too will find food in the shadow of the Brazil nut tree.

A deer perhaps.

Or maybe this strange, enigmatic jungle climber.

A sloth.

[jaguar pants] The sloth had just enough of a head start.

It's escaped the jungle's greatest ground predator, but it's climbing towards something just as fearsome.

The harpy eagle, the biggest bird of prey on the planet.

[ominous music] [monkey screeches] [intense music] [water splashes] Some of the Brazil nut's web of life becomes active at night.

Perhaps Martin's chicken-eater has been waiting for the dark.

But there are other spiders here that even a spider enthusiast must be wary of.

[Martin chuckles] - Okay.

It's not every day you see the most deadly spider in the world.

That's what we have here.

This is a wandering spider.

The reason it's so dangerous to us is, first of all, it's extremely toxic.

The venom of this spider is around 18 times more deadly than that of the black widow.

It has extremely large fangs, it can get through our skin extremely quickly.

Thirdly, it's exceptionally aggressive.

Just a slight tap on one of its legs immediately provokes a response.

These things jump and bite, they don't just bite.

Before an anti-venom was developed, up to a thousand people a year were dying from this spider in Brazil alone.

It's one of those spiders that you don't want to take your eyes off... For very long.

Nothing on this earth would make me touch this spider.

Let's leave him in peace.

- [Narrator] In the jungle, the safest place may be deep inside your hammock.

- Night, all.

[tense music] [monkeys howling] Well, apart from the dawn chorus of monkeys this morning, it not a bad night's sleep actually.

[monkeys howling] They know I'm talking about them.

They're just proving a point now.

It's not funny!

Show some respect for people sleeping!

[monkeys howling] - [Narrator] Even by day, the Amazon holds unexpected horrors.

[unnerving music] As a veteran traveler, Martin knows you must keep your most sensitive body parts out of water, because of a fish called the candiru.

It swims towards urine, burrows into the source, and then sticks fast with backward facing barbs.

The only solution is to cut it out with a sharp knife.

But Martin is undaunted, and he may be closing in on his quarry.

By day, tarantulas hide in burrows under big trees.

If Martin can find a likely hole, then he's all set to unleash some home-made technology.

- Ah, now that's more like it.

Base of a tree, and there's a big hole down there.

It's dry.

It's a nice, smooth shape.

It's away from any water, shielded by the tree itself.

Now, under normal circumstances, we'd have to wait until night, but we've got a way of doing a sneak preview.

Tarantula-cam.

Years in development and literally pounds spent, tarantula-cam involves a little security camera, five little LED lights on the top there, and the piece de resistance, the tricycle, for maneuvering around tight corners.

[dramatic music] All systems go.

- [Narrator] Is tarantula-cam about to meet a monster?

- It goes back quite a way.

Oh my God!

There's something looking at me.

It's a possum, or a mouse.

[Martin laughs] It's checking me out.

I'm sorry, mate.

[Martin laughs] Look at that!

[Martin laughs] So no tarantulas, unless they're very, very odd bedfellows then anyway.

I'm chuffed with that.

At least the camera works.

Camera works a treat.

Who knows what will be down the next hole.

This is fantastic.

[Martin laughs] [thunder rumbles] - [Narrator] One of the challenges of exploring the rainforest, is that it isn't called that for nothing.

[calming music] Giant trees like the Brazil nut generate their own local climate.

They release moisture which forms clouds, and they produce rain.

[wondrous calming music] Here, rain falls at least 200 days a year.

- This could last for minutes, it could last for hours, it could last all day.

You've just got to go with it.

- [Narrator] Trees soak up half the water, and the rest escapes to feed the great river.

[dramatic piano music] There's a direct link between life and rain, because the more it rains, the more diversity of life a forest holds.

[dramatic piano music] The Amazon forest creates some the biggest storms on the planet.

[thunder rumbles] More than 6 feet of rain falls here each year.

[dramatic piano music] Sometimes it rains so hard that it floods over 135,000 square miles of forest.

[dramatic music] This flooded world is a strange, submarine landscape.

The forest floor may be 30 feet underwater.

Terrestrial animals become aquatic.

[dramatic music] While mammals go into the water, the fish try to leave it.

The hatchet fish leaps to avoid predators.

The arowana leaps for spiders.

[dramatic piano music] [water splashes] The flood lasts for six months.

The Brazil nut tree flourishes on higher ground, but its old, empty pods trap their own mini flood, and this attracts a strange web of life found nowhere else on earth.

A poison dart frog carries a tadpole on its back.

It's been scouring the forest for one of these pods.

[unnerving music] A mosquito has laid its eggs in here already.

In the race to grow up, the larvae turn cannibalistic.

[unnerving music] No mosquito will ever make it out of here.

The tadpole is a predator.

But the tadpole's not safe either.

There's another predator in this cavern, a damselfly larva.

It's not a great predator, but then, it doesn't need to be, The tadpole's trapped.

[unnerving music] Thousands of species make up the web of life around a Brazil nut tree.

Could just one hold the key to the tree's mystery?

Why will it only bear fruit in virgin forest?

David Roubik of the Smithsonian Tropical Research Institute suspects bees, because they pollinate big trees.

But, they don't always welcome close investigation.

- Looking up a massive strangler fig and a massive stingless bee nest, one of the aggressive ones.

Right now, there are bees raining out of the nest, and cascading down here and finding me, and laying into me wherever they get a grip.

If you're not a little disciplined, you tend to lose it.

The pain kicks in, the smell, the continual squeaking, and then the sticky resin that they're starting to put on me now.

Ouch.

I can say that's truly an effective defense, and if I were unprotected, they'd be all over my head primarily, and this would be too much.

I'd run.

I'd run as fast as I could.

Ouch, look at that.

And if I try and brush them off, they're stuck on with resin, they're holding on with their mandibles.

And they're not breaking the skin, but they're coming close.

Time to go.

[wondrous music] - [Narrator] David climbs some 130 feet to the tree's canopy to find the bees that pollinate its flowers.

[wondrous music] The flowers are out at the end of very thin branches.

But bees are strongly attracted by smell, and David's brought a special chemical with him that he hopes will act like a bee magnet.

[wondrous music] - The bait's out.

The bees are on their way, there's nothing to do but wait.

[wondrous music] They're just showing up now.

One big one, one little blue one.

[wondrous music] - [Narrator] The bees pollinate the tree's flowers, and only then will they produce their giant pods.

[wondrous music] The bees travel around the forest.

Maybe the solution to the tree's mystery lies at the other end of their journey.

David follows them.

[bee buzzes] [dramatic music] They leave the Brazil nut tree's own patch of forest way behind.

[wondrous music] A mile away, David finds the same kind of bees flying around a rare, fragrant orchid.

[bee buzzes] - Ah, great.

Some luck.

A fallen branch from the tree, and that's one of our orchids, the kind of orchid a bee would love.

Bees are maybe, it's been estimated, a million times more sensitive to the kinds of fragrances like orchid flower than we are.

They are known to pick these things up and fly from over a kilometer away.

- [Narrator] What's going on here?

David has discovered that a male bee can't get a mate unless he's wearing a particular scent, and he has to steal that scent from these orchids.

So if the forest is cut down and the orchids are destroyed, the bees won't be able to mate.

No reproduction means no new bees, which means the Brazil nut flowers won't be pollinated, which means the pods won't grow.

Eventually, the lucrative Brazil nut tree itself will vanish.

That's why the Brazil nut tree needs intact forest to survive.

The rainforest is a vast biological machine, and small, fragile relationships hold the whole thing together like rivets.

Understanding the Brazil nut tree has required a time warp.

And this accelerated view of life now reveals the Amazon's most sinister secret.

[unnerving music] The Brazil nut tree lives for 500 years.

It's a survivor, almost invulnerable.

Yet there is one killer in these forests big enough to take it down.

A seed in an animal's dropping germinates on one of its branches.

The tiny plant sends out roots.

Long roots.

Finally, they anchor in the ground, then they grow, and begin to wrap around the tree for support.

This is the strangler fig.

[roots cracking] The roots take a suffocating grip on their victim.

[dramatic music] The living part of a tree's trunk is just beneath the bark.

It's only a few inches thick, but it carries all the tree's water and nutrients.

[roots cracking] [dramatic music] The strangler squeezes tight and chokes the tree.

It's a death that takes years.

[dramatic music] Eventually, the dead tree disintegrates, leaving a hollow shell standing in its place, the adult strangler fig tree.

[ominous music] Our Amazon journey has one more secret to give up.

Does the chicken-eating spider really exist?

- We've looked at many burrows without a great deal of success.

They've either been empty, or they've had various mammals down them.

We've come across some very promising burrow just here at the roots of this Brazil nut tree.

It's nice and shallow, classic shape, nice and oval shape.

So we're going to send tarantula-cam down and see what lives down at the bottom.

[dramatic music] There's something up there.

There's something up on the right there.

Look at that.

Look at that.

[mysterious wondrous music] Whoa!

It attacked the camera.

[Martin laughs] That looks like a juvenile.

That's not an adult spider.

Excuse me, mate.

Just coming by.

There's another one.

Holy moly.

Are you seeing this?

Are you seeing this?

I think mommy's home as well.

[tense music] I'm very aware about where my hands are just now, because, whoa!

There's a giant black spider hanging on to my camera.

In many ways this ties in very much with what the locals were telling us about.

It's big, it's black, it's long, strong thick-set legs.

It's a powerful theraphosid tarantula spider.

This is our chicken spider, we've found it.

She's coming out.

I'm seeing right underneath her fangs there.

Whoa!

She's got two very large downward pointing fangs, and tarantulas stab downwards.

True spiders' jaws work like pincers.

The legs come up into the air.

Ah!

And the jaws come out, and they strike downwards like that.

And that's how she catches her prey as well.

There we go.

The spiderlings that we saw at the beginning were well grown on, they were prob... Well, it's a little bit difficult to tell, but they were at least 2 or 3 inches across.

Now for spiderlings of that size to still be living with the mother is extraordinary.

It doesn't happen.

Tarantulas aren't gregarious whatsoever, because, of course, more spiders in the same burrow at the same time creates competition for food, creates competition for space, and of course there's an issue when the mother spider is ready to breed again.

But here she is in all her glory.

[Martin chuckles] - [Narrator] Martin will return at night when he hopes the spider will come out of its hole to hunt.

He may be able to study it more closely by picking it up.

[tense dramatic music] - And there.

There, she's got it.

Look at the fangs sinking into that grasshopper.

I suppose when there isn't a chicken coming by, a grasshopper will do.

But what I want to do is try and take a good, hard look up close.

And to do that, I'm going to have to catch her.

[eerie music] I'm gonna try and show you her fangs just so you get some idea of the size of them.

[tense music] The fangs are huge!

Look at that.

It's about that long.

We found the giant chicken spider.

It's something brand new.

It doesn't correspond with any of the other species that we know of in this area, or any of the adjoining areas.

It's surprising in a world where it's so easy to travel around, that there are still animals of this sort of size and reputation that still remain unclassified.

The great blank spaces in the map are not yet all filled in.

This species has not yet been described.

This is something brand new.

[mysterious music] [tense music] - [Narrator] The jungle is a place of infinite complexity.

Science is only beginning to understand it.

Here, life is at its most abundant, yet the connections that keep it all going are desperately fragile.

And who knows what secrets the Amazon will reveal to the next intrepid explorer who ventures into this deep jungle.

[wondrous intense music] - [Presenter] This program was made possible by contributions to your PBS station from viewers like you.

Thank you.

- In a spirit of friendliness, some of the locals here, knowing that I've been out here looking for and searching for spiders, some of the locals have given me the local remedy that they use for...

Things like snake bite, and also for spider bite as well.

It's these little roots.

They're said to be taken orally, or to wipe on to the area that's been bitten.

So we'll just give it a try.

I haven't been bitten, but let's see what the effect is.

Oh.

Okay.

It's as if someone who's just sprayed anesth...

It almost crackles.

Remember Space Dust?

It's like that, with an anesthetic added on to it.

And my tongue's going numb.

If you rub that onto an open wound where you've been bitten, I can imagine that would have an anesthetic effect.

Amazing stuff.

[mellow music]