The savage rocky shores of Christmas Island,
200 miles south of Java, in the Indian Ocean.
It's November, the moon is in its third quarter,
and the sun is just setting.
And in a few hours from now, on this very shore,
a thousand million lives will be launched.
These crabs are all females,
and of a kind that occurs only on Christmas Island.
As darkness falls, more and more of them appear,
clambering resolutely down to the sea
Now it's nearing midnight.
Their numbers can only be guessed at,
but on the whole island there are probably 120 million of these crabs,
and nearly all the adult females among them
have chosen this time for their annual spawning.
A crab like this is carrying about 100,000 eggs,
and she has to shed them directly into the sea if they are to hatch.
That's a hazardous business for her
because although her distant ancestors came from the sea,
she is a land crab...and she can't swim.
So if a wave sweeps her away, she will assuredly drown.
But, nonetheless, her compulsion to launch the next generation is irresistible,
and when she does reach the sea,
her triumph is apparently ecstatic.
The crabs have picked the moment when the tide is at its highest,
so they have the shortest distance to travel to reach the water.
The astronomical numbers of their eggs turn the clear ocean water
into a black turbid soup.
As dawn approaches and the tide recedes,
so the eggs are swept out to sea.
Since life began, the sea has been full of eggs.
The most ancient animals on the planet still live and breed there.
Some, such as sea urchins, may be male or female.
Both sexes discharge their sex cells during the same short period,
so that they unite in the water and form fertile eggs.
The sea brings them together,
keeps the fertilised eggs at the stable temperature
necessary for development,
and transports them for hundreds of miles to new environments.
This perpetually-renewed soup provides a vast banquet
for other floating creatures.
Small complex globes of jelly
drive themselves through the water with lines of beating hairs
and filter out the majority of the eggs.
The most stupendous egg producer of all is the giant clam.
It first discharges sperm...
and then, half an hour later -
because it's both male and female - eggs.
In each annual spasm, it discharges a thousand million.
The water of the sea brings many benefits to the eggs floating in it.
They absorb oxygen from it,
they are supported by its buoyancy, and transported by its currents.
But out of water, on land, life is not so easy.
Here, eggs have to have shells if they're not to dry up.
These elegant capsules were laid by an owl butterfly.
They're only the size of a grain of sand.
The shells are not only protection, they're meals.
The mother butterfly built them from her body reserves of protein,
so the youngsters get a good start in life.
There's another way of providing food for your developing young.
Instead of getting it from your own body,
you can get it from somebody else's.
That, of course, involves the grisly process of body snatching,
and that's just what's going on in this dried-up mudflat
in the western United States.
This strange insect
is a murderous and very hard-working wasp.
She is digging a tunnel to serve as her nursery.
The sun-baked ground she selects is rock hard,
and digging a hole in it is not easy.
Once the burrow is finished,
the female performs an elaborate dance around it -
remembering its surroundings so she knows exactly where it is.
And then she conceals it, so that none but she is likely to find it.
Her nursery must now be provisioned,
and for that she needs fresh meat.
A caterpillar.
First, she paralyses it with her sting.
Thanks to her dance, she knows exactly where her hidden hole lies.
Each burrow will have several caterpillars in it,
and each addition means stopping and unstopping the tunnel entrance.
The urge to collect caterpillars is so strong
that they'll pick them up anywhere. Watch this.
She has already laid a long yellow egg on the first caterpillar.
When the tunnel is full, she seals it with special care.
She uses a grain of gravel like a pneumatic ram,
vibrating it by buzzing her wing muscles -
one of the few instances of an insect using a tool.
In a few days, when the egg hatches,
the grub will find fresh meat awaiting it.
These cabbage white caterpillars are also doomed.
Another species of wasp injects them -
not with paralysing poison - but with eggs.
Day after day, the caterpillars grow and mature - apparently unaffected.
But inside them the wasp eggs are developing.
Having fed so richly on the entrails of their caterpillar host,
the wasp grubs are ready to pupate as soon as they emerge.
They start straightaway to spin their silken cocoons.
Ten days later, they have become adult wasps,
and are themselves searching for caterpillars.
These babies were given special protection.
Their mother surrounded her batch of eggs with a liquid froth,
which rapidly hardened into a tough capsule.
The young developed safely within
and now they're ready for independent life as hunters.
They're praying mantis.
Their infant bodies are covered with a thin membrane
and each hangs suspended by a thread of silk
while it slowly disentangles itself.
One egg mass produced by a single female
may release as many as 400 young.
While latecomers continue to emerge,
the first-born clamber up over them
and prepare themselves for adult life.
Frogs have never entirely abandoned the aquatic life.
Their young - tadpoles - still swim and breathe through gills.
So most adults return to ponds and streams to lay their eggs...
but not all.
This Trinidad tree frog creates its own watery nursery up in a tree,
where eggs can develop out of reach of predatory fish.
The female pulls two leaves together with her hind legs
and extrudes her eggs between them.
The eggs are surrounded by a sticky jelly
which holds the leaves together.
As they emerge,
so the male on her back discharges his sperm and fertilises them.
Over the next eight days, the eggs slowly turn into tadpoles.
Once the first eggs hatch, the jelly begins to dissolve.
The leaves separate and the liquid within starts to trickle out.
And with it come the tadpoles.
But this is no disaster.
The tadpoles drop into a new existence,
for their parents always build the nurseries overhanging water.
Here, they can find something to eat
and start to build their adult bodies.
This South American rain frog is totally independent of pools and rivers.
It lays its eggs on the ground.
But each small globe is full of liquid.
The tadpole not only develops inside this capsule, but stays there -
swimming in its own personal pond until tadpole becomes frog.
Each egg within it also has granules of yolk,
so the tadpole has all the food it needs in order to grow and develop.
When the young finally emerge,
they have no need to swim.
Like their parents, they have lungs and legs.
Birds' eggs contain great quantities of yolk.
On its surface, beneath the cushion of clear albumen,
lies just one fertile cell.
In the sustained warmth, it grows, divides and grows again.
Within two days, a beating heart has appeared.
Blood vessels spread around the yolk,
collecting its nourishment and transporting it to the embryo.
Twelve days later, the little creature has legs.
And beneath the tracery of blood vessels,
the tiny head is virtually complete.
Fifteen days, and feathers are beginning to sprout.
21 days after incubation started,
the moment for hatching has arrived.
Once dried, the downy feathers help the tiny body to retain its warmth.
The chick is ready to start a new stage in its life.
Young birds, even while they're still within the egg,
must be kept warm if they're not to die.
Most are brooded by their parents, but the mallee fowl of Australia
use a different method.
They warm their eggs with rotting vegetation.
A pair build themselves a huge mound of sand.
In its heart lies a layer of leaves.
Every few days throughout the breeding season, the female comes to lay
and the male kicks away sand to expose that layer.
Her egg, compared with her body, is gigantic,
and as soon as she's produced it, the male covers it up.
Now the temperature must be carefully monitored.
The male measures it with his beak.
Even when visitors approach,
he stays bravely beside the mound to keep an eye on things.
If the mound is too cold, he piles sand on top.
If it's too hot, he kicks it away.
So obsessed is he with managing this mound...
that if someone interferes with it,
his first instinct is to put that right.
If I flick sand off, he flicks it back.
The chick has to dig its own way up through the sand.
It's able to do so because that huge egg contains so much yolk
that the chick could stay in it, gathering strength, for 49 days.
Crocodiles too keep their eggs warm in nests of rotting leaves.
The maintenance of temperature has particular significance for them.
The saltwater crocodile of Australia builds her nest on a river bank.
She digs a deep hole in the peaty soil.
In it, she lays several dozen eggs.
These eggs have one strange characteristic -
even though they have left her body,
the sex of the babies within them is not yet fixed.
It will depend on how she looks after them.
She covers them with dead leaves, which, as they decay,
will produce the heat the eggs need in order to develop.
And it is this that determines the sex of the babies.
At 30 degrees Centigrade, they will all be female.
Two degrees higher, and they will be all male.
In between, they will be half and half.
If the nest temperature rises two degrees higher still,
then a third of the eggs will be male, a third female,
and a third will die.
Their emergence is less arduous than that of a bird,
for reptilian shells are leathery and easily broken.
The babies are so well formed
that even before they leave the shell, they can bite.
Animals care for their eggs and young in many different ways,
but peripatus - a curious creature, half worm, half centipede -
provides the ultimate in parental protection.
The eggs develop inside the female
and stay there until they're so advanced
that they can survive without the protection of a shell.
So the young peripatus gets a good start in life.
No waiting around defenceless, imprisoned in an egg.
It's able to feed and hide itself just as soon as it leaves Mother.
These fungus gnat grubs also give birth to live young,
but they haven't yet mated - they're not even adults.
But there's a mushroom available
and they need all the mouths they can get to consume it.
So the unfertilised eggs hatch while they're still within the females
and the new babies feed on their mother's internal organs,
so that she eventually is reduced by her own young to a sausage skin,
through which 30 or so babies force their way - at both ends.
Each is a clone -
genetically identical to its single parent.
Each of these 30 can do the same trick in six days' time.
In six weeks, if there were enough mushrooms,
there could be 20,000 million - all identical.
It's not only females that can give birth.
A few exceptional males also get pregnant.
The male pipefish develops a sticky underside
where the female deposits her eggs.
Flaps of skin grow round them, and when the time comes,
the young wriggle out to take their chances in a dangerous world.
Once they leave their father's body,
they're easily picked off by hungry sticklebacks.
But the babies who are cared for in the most comprehensive way
within their mother's bodies are mammals.
The shock of leaving the warm, protected haven of a mother's body
and entering the harsh, relatively cold, danger-filled world outside
is inevitably traumatic.
Baby antelopes, whose parents have to travel continuously to find food,
must be as fully developed as possible,
for they need to walk within hours, groggy though they may be.
Chinchillas are born in the high Andes.
Their world is a very cold one.
Their mothers make no nests for them, so they are born fully furred.
Were they not, they might freeze to death.
Perhaps the trickiest mammal birth of all is that of the bat.
For it, after all, has to arrive in this world
while its mother hangs upside down from the ceiling.
Whatever happens, the baby mustn't fall.
While mother hangs acrobatically from one leg,
she stretches out the other so that the web connecting it to the tail
forms a cradle in which to catch her newborn babe.
One infant is all that a bat of this species can produce at one time.
Her mammalian nature dictates that she keeps it within her body
until it's well developed,
and even one is a very heavy load when flying.
Now she feeds it from her own body with that special food - milk -
which is all that a newly-born mammal can digest.
The arrival in the world of this baby,
so tenderly nurtured by its mother,
could hardly be more different from that of so many creatures that live in the sea.
Birth for the Christmas Island crabs
is a comparatively protracted affair.
For 28 days, they float helplessly in the sea,
slowly increasing the size and complexity of their body,
until at last they are just recognisable as miniature crabs,
but very few of them live as long as that.
Fish eat them in huge quantities, currents sweep them away into the open ocean.
So most years, the entire spawning of billions is totally lost.
But, almost miraculously, about one year in five,
a few hundred thousand appear in the waves off the coasts
where they first fell into the water as eggs.
Then these little creatures, no bigger than ants,
valiantly struggle ashore.
A single female crab, during her lifetime,
may produce a million eggs.
If just one survives,
then she might be just as successful as a bat, an antelope,
or any other creature that each year devotes all her energies
to cherishing and feeding a single baby.
So in a multitude of different ways,
new lives appear on Earth,
and each starts off on its own individual odyssey.
They've survived the first of their trials,
but they'll have to face many more
before, in turn, they too will have a chance to give birth.
Few babies have such a compressed childhood as this elephant seal -
born on a beach in Patagonia only a few days ago.
Its mother can't feed out of water, so she won't stay here for long,
and her pup has to suck the milk it needs from her as quickly as it can.
The milk contains twelve times more fat than cow's milk.
The mother produces it directly from her blubber,
and the pup converts most of it straight back to blubber.
The nursery is dangerously crowded,
and pups can easily be crushed and killed by the huge bulls
as they quarrel and chase after the females.
After only three weeks, the pup has quadrupled its birth weight.
But its mother is now starving. She has to get back to the sea.
So now this pup is on its own.
And it'll remain here for another six to eight weeks
while it converts the fat it took on so urgently from its mother
into flesh and bone,
and gets strong enough to go out to sea.
And that task of gaining size and strength
sufficient to survive unaided
is the main task of childhood.
And the main trial of childhood is avoiding danger and remaining alive
during this difficult period when an animal is almost defenceless.
In the Russian Arctic, at the beginning of the brief summer,
snow geese babies are hatching.
Their thick down protects them from the cold
and they instinctively peck for food
almost as soon as they're free from their shells.
But they don't wander far from their parents,
for like all ducks, geese and many ground-living birds,
they become fixated on the first large moving things they see.
Those are nearly always the legs of their parents,
and they will follow them all their childhood.
So when mother and father move on, they all move on.
An Arctic fox.
When the geese started nesting a month ago, the coast was icebound.
Now the ice has melted, and the family start the journey to the sea
where they can find food.
If they can, they float.
But most of the journey has to be done on foot -
the young can't fly and their parents won't desert them.
And that is real devotion, for the coast is 30 miles away.
That imprinted compulsion to follow mother's legs
and stay near the protection of her beak
will never be more important.
You might think that parental responsibility wouldn't trouble an insect,
and it's true that most, having laid their eggs, abandon them.
But not the female lace bug.
She protects her newly-hatched young with as much diligence and courage
as any goose.
This is one of her many enemies - the larva of a lacewing.
It stabs the young lace bug with its stiletto mouthparts
and sucks it dry.
But in its death throes, the infant bug raises the alarm.
It discharges a smell that summons the mother.
What weapon she has to fight such an enemy is difficult to see.
Nonetheless, she wins,
and shepherds her charges away to feed elsewhere.
But there is always danger.
A jumping spider.
Once again, back into battle.
Her hard wing cases seem to protect her from the spider's poison fangs,
but, even so, it's a brave display.
Even a spider, apparently, can be seen off
if you have the courage of motherhood.
A mother shrew hides her babies, often under a stone.
Having herself fed on insects, she comes back to feed them on milk.
But if she's alarmed and suspects that her nursery has become unsafe,
she gives her young - whose eyesight is not very good -
a command with an ultrasonic squeak,
which we can't hear, but which they obey immediately.
This way, no one gets left behind.
Mexican three-tailed bats
park their young in a communal nursery - a creche.
All these adults are females
who flew north up to this cave in Texas a few weeks earlier,
leaving their mates to their own devices in Mexico.
The cave is a perfect maternity ward for them.
It's warm and dry
and the surrounding countryside is rich in insects to feed on.
But there aren't many caves like it, so it's intensely crowded.
A million mothers chose this one,
and now there are a million newborn babes here as well.
In the late afternoon, the mothers leave to feed.
The departure starts before it's properly dark,
for it takes a long time for a million bats
to stream out of the relatively small cave-mouth.
The babies they leave behind are massed in one huge creche.
It was important for them to cluster together when they were first born and naked
in order that they should keep warm.
Even now, when they're beginning to grow their fur,
staying together saves energy.
But imagine trying to find your baby among this lot.
Through the night, mothers visit the creche to feed their babies milk.
This mother knows the layout of the cave well enough
to have landed quite close to where she left her baby,
but a lot of jostling goes on here,
and the baby may have moved a yard or so.
As she searches,
other hungry youngsters struggle to reach the nipples in her armpits
and steal a drink.
If a baby doesn't get a proper feed once a night, it's likely to die.
On the edge of the creche,
a youngster waits for its mother, who hasn't returned for some time.
And below, scavengers await for corpses that might fall.
The mother's main way of finding her baby is, astonishingly,
by recognising its cry - even in this pandemonium.
At last. This is her baby.
And at last it feeds.
Vast nurseries like this one
can only exist if there's an abundance of food around.
Not far from Texas, in Florida, the situation is very different.
The white sand on which these scrubby pines grow
is so poor in nutrients that there's little to sustain adult animals,
let alone their babies.
Even birds find it a hard place in which to live.
Food is hard to find and there aren't many places to build a nest,
but it's the home of an interesting bird
that has been studied almost as intensively as any bird in the world.
And this is it!
The Florida scrub jay.
Every jay in this part of the world has been banded
for the past almost 20 years.
We know who each one is and how they fit into the community.
This one, with three rings on her right leg, is a young female.
She was hatched last year on the territory to the left here.
This one, with bands on both legs, is, in fact... Ooops!
..the dominant male, who has a nest in this territory.
Food is so scarce that more than two adults are needed to search for it
if a nest of chicks is to be kept supplied.
This bird is not the parent of these nestlings.
It's one of last year's chicks who's helping to raise this year's brood.
Young female helpers, after a year or two,
usually leave to look for territories of their own,
but young males may stay on for as long as seven years.
One of them may inherit the family estate and nesting site
when the old breeding male dies,
but most will never father a brood.
Instead of producing their own young,
they find their reproductive reward
in helping to raise their brothers and sisters.
Guarding the food supply is just as important as collecting it,
and some of the helpers act as sentinels...
keeping an eye out for thieves.
This is a trespasser from a neighbouring territory,
sneaking in to try and steal food.
That can't be allowed.
So teamwork saves the nest.
Indeed, as a result of studies here,
we now know that pairs with teams to help them
are much more successful in rearing their young.
Elephants also help one another to bring up their babies -
at least, the females do.
The males, when they become adult, wander off
and live more or less solitary lives away from the herd.
A new baby is the focus of great interest and affection -
not only from its mother, but from elder sisters, aunts,
and especially the old lady who leads the herd,
who is almost certainly its grandmother.
Sometimes, indeed, everyone wants to have the privilege of being nanny.
This visiting bull is not used to infants.
Great consternation among sisters and aunts.
Childhood, of course, is a time for play,
and play is a way of finding out about the world around you
and acquiring the skills you may need later.
Playing in water is fun not only for infants, but for adults.
It's a pleasure that elephants never seem to lose,
no matter how old they are.
Still, it takes a bit of getting used to.
And how do you get your legs clean afterwards?
Elephants have a long childhood.
Most don't reach the age of puberty until they're 11 or 12 years old.
As they approach that time,
they begin to try out some of the things that adults do.
An elephant doesn't need to be a fast learner.
It's a strict vegetarian and the range of food it collects is small.
It doesn't have to worry unduly about enemies -
its great bulk as an adult is a protection in itself.
And if you live for 60 or 70 years,
then there is no great hurry to grow up
and assume adult responsibilities.
And, in any case, it takes time to build a body
that will eventually weigh five tons or so.
Chimpanzee childhood is more complicated.
Chimps feed on a wide variety of things,
and a youngster must know what's good to eat and what isn't.
They're very excitable animals, with a complex social life.
A chimp must learn how to behave towards different individuals,
and there are all kinds of physical skills to be acquired.
The baby spends the first few months of its life clinging to its mother.
From this privileged and protected position,
it has a grandstand view of what's going on and how things are done.
These particular chimps, living in the Ivory Coast forest,
have devised a special skill of their own.
They've learned how to crack nuts.
These are now a favourite part of their diet.
But when you're only nine months old,
watching mother crack nuts loses its fascination after a bit.
The shells, on the other hand, have possibilities as toys.
(CHIMPS SHRIEK)
You also need to learn pretty quickly
who is likely to be your friend and who it's safer to steer clear of.
This older infant is beginning to follow the big boys
and copy the way they behave -
discovering what life is like among the grown-ups.
And mother is always there to provide comfort and protection
if things get a bit baffling and worrisome.