Our world is not always the same.
Hidden from our view lies a different world.
Creatures utterly unlike us.
(THUNDER CRASHES)
Almost alien.
Yet they are more numerous than any other group on the planet.
Welcome to the fascinating world of the arthropods.
Spiders, scorpions and insects.
Today we have new camera techniques
that will allow us to reveal in greater detail
than ever before their lives.
The way they fight and feed and reproduce.
This series uses specially developed 3D camera technology
to study the micro world in extraordinary detail,
both on location and in specially constructed environments.
We'll witness their births, the challenges they face,
and the moments when their lives hang in the balance.
And that may help us understand how it is that today
over 80% of all animal species on this planet are arthropods.
In this series we will see the way they have evolved.
From the comparative simplicity of the millipede,
to vast colonies that contain hundreds, even millions,
of individuals.
We'll witness the most extraordinary transformations
in the animal kingdom.
We'll meet ants that farm,
spiders that can cast their webs...
..and the bug that wears the bodies of its victims as a disguise.
Welcome to a strange and dangerous world.
Our planet's rainforests are home to millions of animal species.
Nearly 90% of them are arthropods, some call them bugs,
and they're all searching for food.
In fact, there's food for most of them everywhere,
because over half of all bugs eat plants.
Millipedes were among the first arthropods to move up
out of the water onto the land.
They can have up to 750 legs,
grow to lengths of 30 centimetres and live for as long as seven years.
And this body plan is so efficient
that it's remained largely unchanged for hundreds of millions of years.
Their body is divided into segments, each with its own set of legs
and internal organs.
A heart runs the entire length of it,
supplying each segment with oxygen.
It eats decaying leaves and plants,
just as its ancestors did over 400 million years ago.
Millipedes are peaceful creatures,
but they don't have the forest to themselves.
There are other multi-segmented creatures here
that have a very different way of life.
Centipedes.
They are meat eaters.
Centipedes are closely related to millipedes,
and they prey on other bugs.
There are over 8,000 species of them,
and they all have poisonous stings.
This one lives in caves in India.
Their powerful, independently moving legs
make them much faster than millipedes.
This is the one to be feared most -
meet Scolapendra.
But it's not the only top predator here.
This Red Claw Scorpion from Tanzania
is not as fast or as agile,
but its powerful pincers and sting
make it every bit as deadly.
Scorpions and centipedes are competitors.
They hunt the same prey...
..and in the same territory.
And because of that,
if they meet, they fight.
Scolapendra uses all its strength
to try and get under Red Claw's armour.
But the scorpion's defences are too strong.
It's not Red Claw's attack that wins the day,
it's Scolapendra's weak defence that loses it.
If you can't defend yourself,
you're not likely to stay alive for long in the micro-world.
Australia.
Home to a beetle with one of the oddest defences.
This is a pie dish beetle.
The outback certainly gets very dry,
so you might think that this strange shell
is just for collecting water,
but its primary function is defence.
A Mantis.
Normally a hunter, but with this potential prey,
it doesn't know how to even begin.
But the pie dish beetle's armour
does have its disadvantages -
it's not what you might call manoeuvrable.
Other Australian insects have a different defensive strategy.
This stick insect relies on camouflage to make it invisible,
but that too comes at a cost.
Being shaped like a stick makes it difficult to fly.
So if a predator does find it, it could be done for.
A huntsman spider - and it's ready to strike.
It's one of the fastest and most agile of all spiders.
But the stick insect doesn't even try to escape.
She has a weapon of last resort.
A milky substance from the glands behind her head.
The spray can reach half a metre,
and she'll have enough to have a few goes before running dry.
It fills the forest with the scent of peppermint.
To the huntsman, it's an unbearable irritant.
So the stick insect is free to graze in peace.
Chemical warfare like this
is widespread in the world of micro monsters.
And one insect uses a version that is so powerful...
..it can actually kill.
Ever since they first appeared on land,
the arthropods have been fighting one and other -
over food, over territory, over a mate.
The ways they have developed in order to do so
are truly astonishing.
On the floor of forests almost anywhere in the world,
you'll find these -
bombardier beetles.
They look fairly harmless,
but not many creatures are foolhardy enough to try and eat them.
A mantis.
Some mantises are so large and strong,
they can even kill small birds.
A beetle should be easy.
But not this one.
A fraction of a second after the mantis strikes,
the beetle squirts hot gas and caustic chemicals in its face.
The chemicals are produced by a reaction in its abdomen,
which generates enough heat to bring the liquid close to boiling point.
The bombardier's spray can be deadly to smaller creatures...
..but the mantis is large and it survives.
As does the beetle.
On the African savannah,
there's a hunter that sets its traps
wherever there is dust or dry sand.
This is the lava of an ant-lion.
As an adult, it will look something like a dragonfly,
and then its sole purpose will be to mate.
It'll barely even eat.
But now as a larva, its task is to feed and grow.
To do that, it digs a pit trap in the sand,
and buries itself at the bottom, jaws uppermost.
It can jerk its head so violently
that it can shoot up sand grains like bullets.
And now it waits.
An ant wanders into the pit...
..and loses its foothold.
The ant can't climb out.
The sand slips from under its feet.
Eventually, it tires.
And the ant-lion drags it beneath the sand...
and devours it.
For the ant-lion, remaining hidden is a good way to hunt.
And there are a multitude of places to do that
in a forest.
Here there are predators that set perhaps the most
perfect of all ambushes.
This female trapdoor spider lives in a burrow with a camouflaged lid.
And she'll stay here for her entire 20-year life.
Around the burrow,
she's laid out a network of invisibly fine strands of silk.
She'll pounce on anything that trips on them.
Occasionally, she tests to see that her door opens smoothly.
But mostly, she waits.
A cricket.
Got it.
She pulls her prey into the burrow -
so that she can eat it in safety and at her leisure.
But some bugs have such perfect camouflage
they're virtually invisible,
even though they're totally exposed.
Predators use camouflage to hunt their prey unseen.
Their victims use it to avoid being found and eaten.
But disguise can be a potent weapon.
In the forests of East Africa,
one insect has taken its camouflage
to a bizarre and somewhat gruesome extreme.
This is an assassin bug.
To us, it's easy enough to spot because it moves.
To its prey, that's irrelevant
because it smells like one of their number.
The assassin sucks its victims dry
and glues their empty husks onto its back.
This one is already carrying at least 20 corpses.
Its irregular shape makes it hard for other predators to spot it...
..and makes it virtually invisible to its prey - ants.
It enters this ant colony unchallenged.
Its coat of ant corpses masks its own odour.
To the ants, it smells like one of their own,
and that's what matters.
They'll even run straight over the top of it.
The assassin simply takes an ant whenever it feels hungry.
And the body of each victim then adds to its disguise.
Conflict pervades the bug world.
It shapes their bodies.
It dictates their lifestyles.
The ant-lions beneath the sand.
The trapdoor spiders - 20 years in a burrow.
And it's their extraordinary diversity
that underpins their success.
In the next programme, I'll look at arthropod predators.
These are the creatures that must kill in order to eat.
They have evolved the most extraordinary ways to do so.
And they take many forms.
We'll meet a spider that has turned its web into a casting net.
We'll witness the ingenious hunting tactics of another spider
that preys on its fellows.
We'll meet creatures that use the surface of water
like a radar dish to detect their prey.
And an extraordinary wasp that tames a cockroach
so her young can eat it alive.
We'll encounter the most deadly creatures of the micro-world.