In the beginning, there is the fertilized egg.
Its form couldn't be simpler.
But this will change.
It's a piece of work to craft a creature from a single cell.
By the time it enters the world,
every living thing has experienced an odyssey of alteration.
Change doesn't stop with hatching or birth.
Growing up is also a story of transformation.
A newborn kangaroo can grow over 50,000 times in weight.
Some creatures do far more than simply grow up.
They reinvent themselves.
A fish can start life as a female but end up as a male.
A bird can grow or shrink a brain area for song to suit the season.
Polliwogs become frogs.
Caterpillars turn into butterflies.
We learn few more curious facts than these.
But it's easy to lose sight of just how astonishing these changes are!
And even weirder transformers live among us.
Turn and face the strange.
Meet the body changers.
"Hey, Emma, come here!"
Compared to the epic alteration of a caterpillar,
our own changes may seem subtle.
But there's no denying that kids change shape
as they turn into grownups.
The brain kicks off our own sexual transformations.
Girls tend to get curvier from estrogen and other hormones.
A child's body and that of many other young creatures
changes shape when it reaches the age for reproduction.
These alterations prepare us to compete for mates,
to have babies, and to care for them.
Boys change in their own way.
They add muscle.
Shoulders become broader.
The body gets hairier.
Vocal cords lengthen as does the jaw.
A child's journey to adulthood is a long one.
A grownup is not just a scaledup kid,
but one rebuilt from head to toe.
Look back at the odyssey of growing up,
and we see that even our faces change shape,
starting in infancy with small chins, huge eyes, and plump cheeks.
We are all body changers
when it comes to growing up and growing old.
It may be no accident that
many baby animals have different face shapes from their parents.
Adults fiind baby features irresistible
a hardwired system that promotes infant care.
Silvered leaf monkeys have DayGlo offspring.
No one knows why, unless it's a reminder
to roughandtumble mothers to handle the baby with care.
The young and old of many animals have different colors
sometimes to conceal newborns that are less able to flee danger.
A young, sexually mature male orangutan has a distinguished, mournful visage.
But in middle age, his face changes shape.
His new jowly look is a badge of power.
Changes in our own faces tell many stories.
A face that forms symmetrically in the womb
and stays that way through adulthood
can be a mark of good nutrition and resistance to disease.
Is it any wonder we are highly attuned to symmetry and fiind it beautiful?
Old age brings new changes as our faces transform again,
keeping a faithful record of wear and tear, loves and losses.
As we change ourselves in the subtle ways that human beings do,
we're surrounded by creatures that become entirely new.
Around us are animals
that live out the youthful fantasy of sprouting wings and flying like a bird.
But we also share the world with animals
whose stories of change echo darker myths.
Hercules' enemy, the manyheaded Hydra,
sprouted two new heads for every one lopped off.
Nature nearly matches legend.
The salamander has powers of regeneration bordering on the magical.
It will need these talents, for it lives not in a fairy tale,
but rather in a world of real dangers.
A redeared slider enters the stream.
The salamander picks an unlucky moment for a swim.
It's a vulnerable creature, unarmored and undisguised.
The turtle has nipped off the salamander's hind leg.
Over three months, the creature miraculously transforms itself
back to an earlier stage of life.
The genes that grew the leg in the first place are activated again.
The new leg will be indistinguishable from the original.
Unique among animals with backbones,
the salamander can regrow not just limbs
but the lens of the eye and even part of the brain.
This beast can survive a bite to the head!
The Hydra lives.
The power to change shape or color offers a special edge in life.
Some creatures change to stay hidden.
Others transform to fiind new kinds of food.
Still other animals change for upward mobility
for the chance to fly or leap to another pond.
This lake is home to two body changers that can be lifelong rivals.
A dragonfly nymph spends the first part of its life beneath the surface.
Everything about this creature seems honed for water.
It is tapered for speed.
Its head has powerful jaws and huge eyesthe better to catch prey with.
It breathes through an anal gill also handy for jet propulsion.
It's hard to believe that this pond predator
sleek as a torpedo, accurate and deadly will one day take to the air.
Wings are already forming.
An amazing makeover is beginning.
But the dragonfly will not be able to
complete its body change without regular meals.
Sharing the pond are gray treefrog tadpoles.
You can't get any fishier than this without actually being a fish.
A tadpole breathes through internal gills.
Its long flat tail propels it like a fish's tail.
Inside, powerful front legs have formed and are nearly ready to burst out.
But not every ungainly swimmer will live to be reborn as an elegant leaper.
With a secret weapon locked and loaded,
the dragonfly nymph waits for an opportunity.
Folded up under the nymph's head is a hinged lip with a grasping tip.
This tadpole's dreams of frogdom are dashed.
But in these death throes, a chemical is released
which fellow tadpoles take to heart or to tail.
In two weeks, tadpoles in the area transform remarkably.
Their tails turn a shade of red.
The colored tail may protect tadpoles from attack
like a neon sign flashing "Don't Eat."
Why this works, no one is sure,
but there's no need to turn tail with a tail turned red.
The pond is abuzz with changing bodies.
Not only are tadpoles about to turn into frogs,
they've already changed colors.
At the age of five weeks, tadpoles, both red and cleartailed,
shed their underwater ways.
Rear legs emerge slowly.
Front legs pop out of gill slits.
The tail is absorbed.
This frog may not have turned into a prince,
but the tadpole's transformation is no less astonishing.
An airbreathing, bugeating, lillyhopping, sweetsinging adult
has emerged from a silent scumsucking swimmer with gills.
Now is the dragonfly nymph's time to change.
It's been lurking in the shallows by the shore,
waiting for just the right moment to abandon the water forever.
Tonight is perfectcalm,
since rain or wind could dislodge the dragonfly at a vulnerable moment.
The nymph has crawled out of the water and fastened itself to a stem.
It is now committed to the air.
A brand new creature emerges from the old.
The husk of the nymph splits open.
In a single magical hour, an adult struggles out.
At first, its goggle eyes look like deflated beach balls.
But soon they are pumped up to full size
some of the keenest eyes in the insect realm.
In the remaining hours before dawn,
the dragonfly pumps blood into its soft, wet wings,
doubling their length.
The dragonfly has changed from a jetpowered aquatic hunter
armed with a hydraulic spear
to a peerless aerialist that will stalk on the wing.
About two hours after emerging, the dragonfly takes flight.
Once master of the pond bottom,
the dragonfly now controls the air space above.
No other insect devotes as big a share of its body weight
to flight muscles as the dragonfly.
Scuba certification has been traded in for a pilot's license.
As larvae, dragonflies once hunted tadpoles.
Adult frogs sometimes have the chance to even the score.
A dragonfly is a curve ball on the wing.
There's nothing wrong with the occasional whiff
if now and then you connect with a solid double.
Just as body changes can take place in individual creatures,
so they can occur across generations.
That's evolution.
Natural selection is the long process of picking winners and losers
among organisms that differ slightly from their parents.
Without bodychanging over generations, evolution would come to a standstill.
As it is, change adds to change to create the entire parade of life.
Life may have begun with a blob that by chance transformed.
When alterations were successful,
the transformer thrived and transformed again.
One of natural selection's winning picks
is the trick of morphing during a single lifetime.
Plankton is a potpourri of larvae
body changers of many species at an early stage of life.
Creatures like this have an edge:
Each stage can be honed for a different job.
Now they are shaped for spreading arounddrifting on the currents.
Soon these beasts will be changed beyond recognition
into new forms tailored for feeding and reproduction.
One member of the plankton, a crab larva,
starts life with scant resemblance to its parents.
It shares the ocean with another tiny drifterthe seaslug.
This relative of the snail
hatches wearing a transparent shell a suit of crystalline armor.
Seaslug and crab, similar as larvae,
may confront each other as adults, as different as two animals can be.
Having shed its shell,
the seaslug eventually becomes an adult four inches long.
It now has a new organ a feeding hood.
The billowy hood caresses eel grass to catch food like skeleton shrimp.
Like a submarine Venus fly trap, the seaslug closes up,
trapping prey like skeleton shrimp with a zipperlike seal.
Growing on the seaslug's back are other new organs
fleshy paddles that will soon save its life.
As the seaslug feeds,
it is being watched by its former planktonmate.
The crab has changed into a formidable scavenger
with molarlike grinders on its claws.
Blind except perhaps to light and dark the seaslug approaches danger.
The crab pinches at the seaslug as hard to grab as a water balloon.
Finally the crab gets purchase.
But it gets only a small serving of seaslug,
whose paddles pop off by design.
The seaslug swims away with wild undulations.
Only a stump remains where once there was a paddle.
The missing organ may eventually grow back
Once a tiny drifter, this body changer is now rebuilt for escape.
Up the water column without a paddle, the seaslug leaves the crab,
its fellow transformer, with a meager souvenir.
Transformation is not just the privilege of living things.
The morphing of clouds may offer nothing more than delight.
The morphing of bodies serves a more important goal: Survival.
In the Arizona desert, the weather shifts late in June.
After eight crispy months, skies darken.
The monsoon has arrived.
The pounding of the rain has stirred strange creatures beneath the soil.
In this small, evaporating pond,
animals race against the clock to transform.
Tadpoles of the spadefoot toad must absorb their tails,
grow lungs, sprout legs.
They must transform from fishlike swimmers
with gills to hopping airbreathers.
If changing from tadpole to toad isn't miracle enough,
tadpoles of this species have two ways to do it
the nice way and the notsonice.
In this hot summer, the pond is shrinking quickly.
It could become a deathtrap a cauldron of bouillabaisse.
As the water level drops,
time is running out for the tadpoles to become toads.
Meanwhile, another creature joins the fray.
Fairy shrimp may have lain dormant underground as eggs for years,
waiting for just the right conditions to rush through their lives.
As the pool dries up, it gets more crowded.
Tadpoles bump into more and more of these crustaceans.
Advantage: Tadpole.
If they end up snacking on lots of Sonoran scampi,
the tadpoles sense that their pond is shrinking fast.
There's something about fairy shrimp
that throws a chemical switch inside some of the tadpoles.
And these gentle browsers now begin to transform into brutes
that will stop at nothing to become a toad.
Some of the tadpoles are turning into cannibals!
This is bodychanging with attitude.
The cannibals are lighter in color and larger.
A huge muscle forms in the jaw the better to grab their neighbors with.
We're no longer on golden pond.
The cannibals grow at breakneck speed on their unneighborly diet.
On the fast track they will need only twoandahalf weeks to become toads.
The slower, mildmannered tadpoles need six weeks to grow up.
The extra time helps them become healthier adults than the cannibals.
But often in the desert, time is a luxury.
And the race goes to the swift and brutal.
It was a remarkable turning point in evolution
when a fish transformed to emerge from the sea,
gulp air and drag itself around.
But what took eons in evolution is an everyday occurrence in tadpoles.
To reach adulthood, spadefoot toads must live fast and hard,
then dig down into cool damp soil before the next drought arrives.
For others in the desert, the season of change has also arrived.
On an acacia blossom, an egg barely visible to the human eye hatches.
A bristled beast emerges.
This caterpillar has a problem.
If it's ever going to become a butterfly,
it must first survive its life as a larva.
The desert is alive with predators like ants and wasps.
This caterpillar has an ingenious defense.
It will soon enlist one of its enemies,
but only after it transforms to develop special organs for manipulating ants.
At the base of the acacia tree, ants have dug a nest.
Most ants like nothing better than dismantling caterpillars.
But these ants love themintact.
They will protect the caterpillar.
That's because the ants march to the beat of a different drummer.
The caterpillar has become the drummer.
This is the sound the caterpillar makes
with body vibrations so tiny we can't see them.
But ants feel the beat through twigs and stems and come running.
A strange rendezvous of two very different creatures
is about to take place.
The caterpillar has, in effect, shouted to the ants,
"Come and get it!"
It's not a ploy.
The caterpillar doles out sugary droplets which the ants lap up.
For the price of a few servings of food,
the caterpillar is surrounded by friendly ants.
Not a bad thing to have the neighborhood
toughs at your beck and call
when you have a soft body and a nasty array of predators.
This remarkable relationship will last for most of the caterpillar's life.
The caterpillar now transforms into a new stage.
Tentacles have appeared strange chemical transmitters
that seem to rile up the ants.
The caterpillar needs the ants to be ferocious: Danger is near.
Another kind of ant lives nearby a predatory species.
An enemy ant has grabbed the caterpillar.
The friendly ants rally in a desperate tugofwar.
Not all battles can be won.
But without the aid of bodyguard ants,
not as many caterpillars would live to become butterflies.
About ten days after hatching, the caterpillar descends the tree.
It's hard to believe this creature will soon shed its wormy form,
sprout wings and head for the heavens.
But that is the miracle of a caterpillar.
Down in the enclave of the ant nest, the caterpillar is reborn as a pupa.
Hunkered inside what looks like a sarcophagus,
the pupa is a creature in the midst of a total makeover.
Nerves are being rewired.
Old organs are dissolving; new ones are being built.
The ants tend this defenseless animal
even though it will no longer feed them.
After ten days,
one of the most radical redesigns in all of nature is complete.
The pupa has become an adult, a butterfly.
This creature's long relationship with ants is now over.
The butterfly struggles to emerge.
It must move quickly.
In fact, if the butterfly isn't out of the nest in minutes,
it will be devoured by the same ants
that protected it for almost its entire life.
As larvae, these creatures were basically enormous digestive tracts
hauled around on caterpillar treads.
As adults, they are flying machines dedicated to sex.
If we couldn't witness a caterpillar turn into a butterfly,
we'd never believe they were the same animal.
It's as astounding as a Cuisinart transforming into a 747.
Some animals undergo one major transformation in their lives.
Others change fashions every year with the seasons.
Dogs may wear heavy coats in winter.
But lengthening days will cause the fiine underhairs to drop out.
Soon, this dog will be cooler in his new spring wardrobe.
Some animals change not only their coat but their color.
The arctic fox wears white for stealthy winter hunting.
By summer, the coat is less than half as thick
Arctic birds like the ptarmigan also change color.
In summer, they're as mottled as the terrain.
By winter, the ptarmigan is a bird of a different color.
Other prey species like the arctic hare
must track the seasons with their wardrobe.
Understatement is de rigeur.
If some animals change for the seasons on the outside,
others are transforming on the inside.
All over North America,
redwing blackbirds prepare for spring with remarkable changes.
Males arrive from winter havens to squabble for territories.
No one gets a home without singing for it.
But this male is out of practice.
He hasn't sung much at all for half a year.
But he's been quietly transforming.
It's now opening day of a new season of song.
The transformation was all in his headliterally.
The blackbird is a brain changer.
Over the past months, one tiny area in his brain devoted to song
has more than doubled in volume.
With his new swelled head, this male now woos females with song.
When a female becomes all aflutter, the serenade has succeeded.
The happy new couple flies off to the shrubbery.
It's time for a little twointhebush.
The burgeoning brain of the male may have kept the sexes in tune this season.
Transformation promoted communication which helped launch the next generation.
Late in the summer, blackbirds glean the fields for the last easy morsels.
Males will transform once again.
The brain's song area dwindles, along with sweet serenades for sex.
Birds are in good company when it comes to changing for reproduction.
For most of its life,
a flowering plant makes stems and leaves, a single pattern repeated.
But when the right conditions arrive of temperature, daylight, or rainfall
a plant will suddenly transform,
producing a brilliant package of sex and advertising.
As one poet put it, "The flower is a leaf mad with love."
Deer browse among blossoms, eating tender leaves and grasses.
A once flowering feast is transformed into a pile of dung.
In the leftovers of a deer's meal,
two organisms will each struggle to survive.
A fungus begins to grow threads invisible to the human eye.
The fungus is transforming for reproduction.
It shoots up stalks as tall as an eyelash is long.
Each stem lifts ripening spores above the deer's ground zero.
Meanwhile, tiny larvae are growing.
The deer was infected with a roundworm.
To survive, these wriggling parasites
must leave their dump of a neighborhood to reach a new deer.
So the worm climbs a fungus stalk
Just below a black beret packed with spores,
water pressure builds.
When the cap bursts, spores can be shot up to eight feet away.
And worms will fly.
One of the parasites lands several feet away.
A passing deer eats it an inadvertent diet of worms.
The roundworm has found a host,
and millions of scattered spores await their fate.
Wintertime.
And the living's hard in the far north.
At least for a relative of the deercaribou.
The landscape is littered with body parts.
Antlers.
Up to 20 pounds of bone, grown every year and discarded.
Males start to grow antlers every spring
a transformation from bald to bedecked.
Antlers are living tissue crisscrossed with blood vessels and nerve endings.
The sensitive fuzzy skin is called velvet.
Each caribou has a signature pattern which can grow back year after year.
It would be no less wondrous
if we were to sprout a fresh arm the same armevery year.
When antlers stop growing late in the summer,
another transformation takes place.
The tender velvet dies and is scraped away until it hangs in tatters.
Each male is now crowned with spikes of unfeeling bone.
Fighting is one reason for the male caribou's transformation.
And this helps solve the mystery of why antlers shed their velvet:
You can't fight a battle if your sword can bleed
and is sensitive to the touch.
Some creatures grow head weaponry every year.
Others, only a single time.
Altogether, male caribou have plenty of company
when it comes to transformations for battle.
If some animals transform what's on their head,
others change what's in it.
This male's appearance and his personality
will transform with his fortunes.
Meet a member of the cichlid family.
He's something of a piscine Austin Powers.
"Oh behave, baby!"
He's the proud owner of a prime bachelor pad
about one square foot of lake bottom.
He's dressed for success or, rather, because of it.
His dark stripes and sharp colors are the marks of a territory holder.
Nearby lurks a male with the dull colors of a wannabe.
In fact, he looks just like a female.
If fish experience envy, this one covets his neighbor's life.
The flashy bachelor invites a female over to suck gravel.
This counts as fiine dining in these shallows.
After dinner, the couple retires to the grotto for a little spawning.
There's only so much a guy can take.
The wannabe has switched on his colors
a kind of warpaint to prepare for battle.
The wannabe wins.
And he is transformed by victory.
He retains his bright colors.
His grievances are redressed
as much as he himself has been redressed in the wardrobe of a winner.
A more profound transformation will soon take place inside his body.
In a week his gonads will plump up thirtyfold in weight
and a brain area dedicated to sex will increase eight times in volume.
At last the new bachelor is ready to take his enlarged gonads for a spin.
Guided by his bigger brain area for sex,
he courts a female with macho motions and furling fiins.
But no male holds a longterm lease in these gravel beds.
The new owner soon discovers the high cost of upkeep for his pad.
Neighboring bachelors are always testing the lot lines.
A neighbor attacks.
The new territory holder is defeated.
He switches off his fancy colors.
His gonads and brain region for sex will soon shrink
He rejoins the ranks of the wannabes.
Some body changers
save their most dramatic transformations for the end of life.
Sockeye salmon are beckoned from the ocean
back to the Alaskan streams where many hatched five years ago.
Some must travel hundreds of miles in an odyssey that can take weeks.
Along the way,
salmon will undergo one of the most remarkable changes in all of nature.
Head shape starts to change.
Every salmon will die by the journey's end.
The only question is
whether they will get the chance to complete their transformation.
Many will be stopped here by a terrible gauntlet of brown bears.
On this journey of the condemned,
the salmon throw themselves upriver with abandon.
The salmon that escape, especially the males,
will now carry on with their transformation.
The head turns green and body red
as the fish prepare to die on their own terms.
Few have made it this far.
Fewer yet will fimish the transformation.
Approaching the spawning grounds, the males achieve their fiinal shape.
A sleek silvery male, over a few weeks,
transforms into a gaudy hunchback with a toothy grimace.
The skin turns smooth and unfishlike as the body absorbs its scales.
In tatters after their journey,
salmon arrive in the shallows where they hatched.
They've lost up to a third of their weight.
Not to mention their looks.
Only one in a thousand has completed this harrowing roundtrip.
With her own changed body,
a female sweeps out a gravel nest and releases her eggs.
A male offers his swirl of milt.
This grotesque body change is still a mystery.
Does the male's hooked face help in jousting matches with rivals?
Does the female choose a male for his new colors,
a sexy but reckless display that draws the fire of predators?
All that's certain is that this change is the creature's last.
And perhaps in death, the fiinal transformation,
the parents offer their decaying bodies to feed the pools
where the next generation will grow.
The life of every creature is a journey of change.
So too is the path of all life since the very dawn of living things.
Though we may resist change,
or wish to turn back the clock no one can tether time.
We are all transformers,
for the story of life is the story of change.