Not much bigger than an orange,
the pygmy marmoset is the smallest monkey in the world.
They live in the largest tropical forest on our planet -
the Amazon rainforest.
Their lives are full of huge obstacles
but they don't let size be a barrier to success.
With chisel-like teeth, they've learned to tap into the trees,
feeding on their energy-rich sap.
These micro-monkeys are the miners of the Amazon...
..leaving their mark across the forest.
Too often in life we overlook the little guys.
Overshadowed by bigger beasts, their lives simply pass us by.
But if we stop and get down to their level,
a remarkable world is revealed.
Take this gecko, the size of just a few raindrops,
but somehow able to weather the greatest of storms.
Or this bird, the weight of a 20 pence piece,
who flies thousands of miles for a meal.
What about this rather plain little fish?
Well, he's a passionate artist whose work deserves its own gallery.
So, while they may be small,
these creatures and others like them have survival secrets
that are amongst the biggest and most surprising on planet earth.
And now, at last, they're taking centre stage.
It's time to meet nature's miniature miracles.
The world is a big place...
..home to some huge animals...
..and exposed to wild weather.
RUMBLE OF THUNDER
So what does that mean if you're one of the planet's small folk?
How are you supposed to make a living in this big, bad world?
Well, you need to adapt.
You must develop extraordinary skills.
And you've got to achieve some pretty mind-boggling feats,
like coming back from the dead.
And, let's face it, there's no greater miracle than that.
But whether big or small,
all living creatures have the same basic needs -
food, finding a mate...
..and a safe place to live.
On an island in the Caribbean,
a tiny crab's biggest issue is home security.
Hermit crabs have soft bodies that make them vulnerable to attack
from predators and the elements.
A naked crab would quickly cook in the intense tropical sun...
..so these miniature miracles have come up with an incredible solution.
They use abandoned seashells as mobile homes.
24/7 protection.
But there's a problem.
Right now, this chap is no bigger than a dice,
but he'll continue to grow throughout his life.
So if he wants to stay safe, he must always be on the lookout
for a new larger shell to move into.
But finding a new home isn't as easy as you might think.
On this paradise island, there's a surprising shortage of shells.
Unless this is the opportunity the small crab's been waiting for.
Unfortunately, it's probably a bit too much to take on right now.
And he's not the only prospective buyer in the area.
Hermit crabs can be anything from a few millimetres long
to the size of a coconut...
..so there's a chance this new home might suit someone else.
With housing stock in such short supply,
the local crabs have learned to do something
really quite extraordinary.
They've joined forces to set up their own property market.
Each crab is looking for the perfect property
with the right shape, opening and weight.
Somehow the crabs reach an agreement
and, incredibly, they start to assemble in a chain...
..largest at one end...
..smallest at the other.
All lined up, they're ready to exchange,
and not an estate agent in sight.
The biggest crab is first to move.
So far, so good. The chain's holding together.
Our little crab gets in position, ready to make his big move.
His size means he's at the bottom of the chain.
But just as he vacates his old shell,
a newcomer arrives on the scene to try and gazump him.
He can't afford to be left homeless.
A death sentence in this tropical heat.
But fortune's on his side.
After all the swapping, there's one empty shell left over.
And he wastes no time settling into his spacious new home.
From the perfect beach hut
to a treehouse hiding one of the world's smallest mammals.
Our second miniature miracle
lives in the giant bamboo forests of south-west China.
Bamboo is the tallest of all our grasses,
with some species capable of growing up to 40 metres.
But this isn't just a big world,
it's also home to some rather bad sorts.
HISSING
So if you're really small, how do you survive in a place like this?
You hide.
A tiny slit in the bamboo stem reveals the bijou home
of the bamboo bat.
A colony of 25 living in a space the size of a teacup.
Each bat is not much bigger than a bumblebee
but it's still a squeeze...
..which is hardly surprising
when you imagine a teacup full of bumblebees.
BUZZING
These micro bats have evolved special adhesive pads
on their thumbs, wrists and feet,
which help them make the most of every corner of their secret home.
But what good is that against what lurks outside?
If it got the chance, this snake would devour the entire colony.
But that's where a miniature home with a miniature front door
comes into its own.
At just six millimetres across, no wider than a pencil,
there's no way the snake's getting inside.
But what about the bats?
How do they come and go through what is possibly
the smallest front door in the animal kingdom?
Well, they've evolved super-thin flattened skulls
and, while it may still be a squash,
they're able to squeeze themselves through the tiny gap.
It's another miracle manoeuvre.
Once the coast is clear, the bats go hunting for insects, like flies,
beetles and winged termites.
And that's where a more well-known miracle comes into play.
Bats are the only mammal that can fly
and one of the few to use echolocation to find food,
sending out sound waves that detect prey in the darkness.
And it's these miraculous skills,
combined with a canny choice of home,
that are the key to the bamboo bat's success in this forest of giants.
But what if surviving means you need to protect yourself
from your own kind?
On the east coast of Australia,
over a hundred species of shark inhabits the tropical waters
of the Great Barrier Reef...
..including the largest shark of all.
The 12-metre-long whale shark is the biggest fish in the world.
Sharing the reef with this giant
is one of the smallest members of the shark family - the epaulette.
He's less than one metre long...
..which, unfortunately, makes him ideal prey
for some of the other larger sharks.
So in a world of bigger, badder sharks,
how does the tiny epaulette stay off the menu?
Without a safe home to escape to, he keeps a low profile
and waits.
Twice a day the tide goes out,
which means conditions on the reef change dramatically.
As the water departs, so do the big sharks.
The water is far too shallow for them now.
But the epaulette's size means he's able to make the most
of this brief moment in the life cycle of the reef.
At last he can stop worrying about being someone else's dinner
and focus on finding his own.
But it doesn't last long.
The tide's still dropping
And soon the epaulette is left high and dry.
If he's not careful, he'll barbecue in the scorching Australian sun.
Even more worryingly, this fish out of water is struggling to breathe.
But the miraculous epaulette has evolved an extraordinary strategy
to cope with this.
By slowing his breathing and heart rate and powering down his brain,
he can survive on his last breath for up to an hour.
When the oxygen levels get critical,
another incredible survival strategy kicks in.
His fins turn into prototype legs.
This cunning fish breaks all the rules...
..and is the only shark that can walk himself out of danger.
The epaulette shark isn't the only miniature miracle
to have evolved remarkable superpowers.
High on a remote rocky plateaux in Venezuela
lives the three-centimetre-long pebble toad.
Unusually for an amphibian, he can't hop.
So, camouflaged to his surroundings,
this hopless toad creeps around looking for insects to eat.
But he's not the only hunter up here.
A toad-eating tarantula.
Faced with the enemy,
the toad employs an unexpected escape strategy.
He transforms himself into a toad-like ball.
Tensing all his muscles, he becomes rigid like rubber.
Perfect for bouncing down the mountain out of danger.
He's safe and, remarkably, completely unharmed.
A female Arabian fat-tailed scorpion
on its regular night-time hunt for beetles.
But while she's looking for food,
someone's eyeing her up as a potential meal.
A desert fox.
Once the moon comes up, its soft light could expose her.
So this scorpion has an extraordinary super sense -
an early warning detection system
that gives her an edge in this nocturnal world.
UV sensitive cells on her shell
warn her it's an hour until moonrise...
..which gives her plenty of time to run and hide
before it blows her cover.
When you're small, life's worries extend beyond just being eaten.
You'd think a single raindrop might drown a tiny Brazilian pygmy gecko.
Tricky when you live in a rainforest.
But these geckos have evolved super hydrophobic skin.
Water doesn't wet them.
Their skin is so water repellent
that even a tumble into a puddle isn't fatal.
These miniature marvels can literally walk on water.
But sometimes even remarkable physical adaptations
aren't enough to help you survive.
East Africa.
Home to some of the world's largest mammals...
..as well as one of its smallest.
A female elephant shrew,
more commonly known by her African name of sengi.
She's 300 times smaller than a lion...
..and 8,000 times smaller than an elephant...
..which makes the vast savannah a very dangerous place to live.
How on earth does she stay safe out here without being trampled?
By living her life at top speed
and with brainpower far beyond her size.
This miniature mastermind has designed and built
a hidden network of trails to get around.
Even when she does encounter danger...
..these trails can mean the difference between life and death.
A monitor lizard.
Drawing on a mental map of her network,
the clever sengi is able to figure out the best escape route.
Our fast-footed fugitive is built for high-speed getaways too.
Like most mammals and unlike reptiles,
her legs are directly beneath her body...
..which makes her less stable
but much faster and more agile than the lizard.
Astonishingly, this tiny tearaway, who weighs less than half a kilo,
can reach speeds of nearly 18 miles an hour.
For her size, she's twice as fast as a cheetah...
..which definitely qualifies her
as one of our miniature miracles of nature.
Life in the fast lane requires a lot of fuel.
But while the sengi's secret network allows her to find food efficiently
and discretely, not everyone has it so easy.
We've all heard of the world's great animal migrations...
..like the massive herds of caribou
who trek 1,500 miles through the Arctic wilderness every year
to find food.
GEESE SQUAWK
And the five million snow geese who fly en mass to northern Canada
looking for a summer feast fit to feed a family.
But these are big animals travelling in gigantic groups.
There's another, much less-known,
but perhaps even more impressive annual migration,
and this one isn't migration on a miniature scale.
This is a miniature miracle on a mammoth migration.
Meet the rufous hummingbird.
This tiny bird weighs less than a 20 pence piece
and yet every spring she flies over
4,000 miles from Mexico to Alaska...
..on her own.
Her destination - Tongass,
part of the largest temperate rainforest in the world.
In spring, when the forest wakes up,
it offers the promise of a seasonal banquet.
Rufous hummingbirds spend the winter in the tropics,
where competition for food is fierce.
Here, they get the place to themselves.
They're the only hummingbird to make this epic annual migration
to Alaska.
But when they get here, they can't afford to rest.
Hummingbirds can flap their wings an unbelievable 50 times a second.
Blink and you can miss it.
Great for hovering but, like any racy sports car,
it's heavy on fuel -
one thing this female doesn't have much of.
After the long trip here, she's running on empty.
If she doesn't eat soon, she might not last the day.
And if it wasn't enough that this mini marathon flyer
has flown all the way from Mexico,