19x09 - Triumph of Life: The Eternal Arms Race

[bunniefuu]

Life must battle to survive.

In four billion years
of hunting

predators have become
better at k*lling.

But their prey have become
better at escaping.

These escalating battles
have shaped every living thing.

Such "arms races" produce
ever-improved weapons...

and strategy.

In these races, the price
of failure can be extinction.

But today's animals are
the triumphant survivors

of a four-billion-year w*r.

For them, the eternal
arms race continues.

For millions of years

the cheetah has largely preyed
on one animal...

the gazelle.

Cheetahs are
master gazelle K*llers

but gazelles are superb
at escaping cheetahs.

The creatures are locked
in an evolutionary arms race

a race for survival, that has no end.

It has made them the fastest
and second-fastest animals

on the African plains.

Cheetahs are swifter
in a straight line

but gazelles can turn
more quickly...

and have great stamina.

Gazelles frequently escape

and only the fastest cheetahs
make regular kills.

The mother's physical qualities
and much of her behavior--

both crucial for hunting--

pass to her young
in the form of genes.

The genetic code is a blueprint
for making a successful cheetah.

But the genetic recipe
for the perfect hunter

is unachievable,
because the gazelle's genes

are also updated
every generation.

This genetic arms race
continually reshapes

both animals.

Arms races
between predators and prey

affect the lives
of all creatures.

There is tension

whenever hunters and hunted
come together.

The shape and behavior
of all these creatures

is molded by the need
to hunt or escape.

The pressures that shape prey

have left the gazelle
agile, fast and vigilant--

qualities useful against all
predators, even the unexpected.

The baboon has no answer

to the speed and agility
of the adult gazelle.

The mother's successful genes
will live on in her offspring.

Most prey are under siege
from all sides

and must balance
the risks of attack

from many different predators.

Staying alive is a juggling act.

In Australia's
Northern Territory

sea eagles can snatch
fruit bats from treetops.

The best defense
against these birds

is to hide in the middle
of the tree.

But this is the worst place
to hide from snakes.

Vines and branches are highways
for the carpet python.

Low-ranking bats, pushed
to the edge of the colony

are in greatest danger.

If their excellent sight
gives them early warning

they move to branches where
snakes cannot reach them.

Safe havens from snakes and
eagles often overhang rivers.

But when water levels are high

this leaves them vulnerable
to another predator.

The noise of roosting bats
is a dinner bell

to a master opportunist.

Crocodiles are
ambush specialists

grabbing whatever they can.

Their strategy is hard
to anticipate or prepare for.

Having escaped
its main predators

the bat is exposed to another.

Crocodiles have been shaped
by a more ancient arms race--

probably the oldest one of all--
the race for size.

The principle is simple: Become
large enough to eat anything

and too large to be eaten.

This same force has helped shape
the world's largest land animal.

Elephants don't tackle prey

but their size
gives them protection from predators.

The ancestors of modern
elephants were far smaller

and regularly fell prey
to big cats.

Rather than become fast like
gazelles, elephants grew big.

These days,
few cats could tackle

such a large
and powerful animal.

For hunter and hunted alike,
being big is a winning formula.

Again and again
across the animal kingdom

large size has evolved
in both predators and prey.

But there's a price to pay
for being large.

It takes a lot of energy

to pack on the pounds
and carry the weight.

A few animals only grow big
when it counts.

This tadpole doesn't waste
energy growing protective bulk

when the pond is safe.

Instead, it diverts
all its energies

to becoming
a North American tree frog...

Unless predators arrive
at its pond.

Dragonflies themselves
are harmless to tadpoles

but the eggs they lay
under the water's surface

will hatch
into something deadly.

Dragonfly nymphs are
more than a match

for a poorly streamlined tadpole
with a body designed for eating.

The tadpole's chances of escape
are slim.

But only the first tadpoles
are easy.

Things in this pond
are about to change.

This tadpole's life is over

but its death will help
its siblings to survive.

The mangled prey
oozes body fluids

containing special
alarm chemicals.

These diffuse through the water
to its relatives

activating genes that trigger
an extraordinary transformation.

Over the next few days

the tadpoles pack on weight
and grow large red tails.

Remarkably, these large,
red-tailed tadpoles

are the same species as the
thinner, brown-tailed variety.

But the red-tails are
the antipredator version.

The larger tail gives them
greater acceleration

making them very hard to catch.

Their color is
more of a mystery.

Red may be a warning
to predators

that these tadpoles are
too fast for them.

Red-tailed tadpoles take
longer to become frogs

but it's better
to arrive late than never.

Sophisticated defenses like this

evolved from millions of years
of conflict

between predators and prey.

Such battles have
ancient origins.

Over 500 million years ago,
only the oceans harbored life.

Predation was a slow
and passive affair.

Jellyfish caught plankton

by simply bumping into it
with sticky tentacles.

On the sea floor

anemones collected food
in much the same way.

Anchored to rocks

these creatures sifted the
currents for microscopic prey.

Animals still alive today,
such as anemones and flatworms

give an idea of what this
world might have looked like.

With no quick predators
on the scene

this was life in the slow lane.

There was no need
for speed or protection.

There were no hard parts;

neither teeth nor jaws
had yet evolved.

The only body designs were based

on soft and spongy
sacs of cells.

But the world was
about to change.

A new kind of gene organized
the sacs of cells

into segmented bodies.

Predators with fins, jaws
and complex eyes evolved.

Now animals could hunt
their food.

Predation had arrived.

Evolution went into overdrive.

Armor was the next
great invention

as calcium from water and stone

was transformed
into protective shields.

Many of the seashells
still familiar today

evolved in just
a few million years.

Scales, acting like chain mail,
were a good defense.

But predators fought back
with improved jaws.

Some scales evolved into spines

which prevented jaws from
getting close to the body.

Bizarre animals like the
spine-covered Hallucigenia

are now lost in time.

Others are still around today.

Soon, even predators
were using elaborate shields

to protect themselves
from larger predators.

But armor is costly to make
and cumbersome to carry.

These clunky designs
were vulnerable

to a new generation
of speedy hunters.

Improved senses allowed
animals to swap armor

for lightweight protection.

Prey could now detect
approaching predators

and simply leave.

With the arrival of senses,
delicate escape artists

found a place alongside
heavily armored creatures.

This ancient era,
the Cambrian period

was the cradle
of complex animals

and the birthplace
of many of life's triumphs.

Among them were the ammonites.

Adjustable buoyancy offset
the weight of their armor.

They were mobile
and well protected.

Efficient predators, they
became the dominant creatures

for a hundred million years

until the arrival
of a predator with jaws.

Ammonites were outgunned.

Their defenses crumbled

as fish exterminated them
from shallow seas.

Relatives of the ammonites
survived in the ocean depths

where few fish could follow.

Today, the nautilus is

the last shelled relative
of the ammonites

and has changed little
in 300 million years.

The nautilus skulked in the deep

while fish flourished above,
dominating ancient seas.

But the fish had
a new challenger

in the shallow waters.

Squid, cousins of the ammonites,
lost their shells

and evolved the speed
to hunt and escape.

To this day, they take on
fish at their own game.

Below, on the reef

the octopus, also a modern
relative of the ammonites

has a defense
against sharp-eyed fish.

Fish rely on good sight
for hunting

but the octopus is
a master of disguise.

Its rapidly changing camouflage
allows it to vanish

in an instant.

The eyes gather information
about the pattern of the reef

the suckers about its texture.

From this palette

the octopus can paint the reef
across its skin

and fool fish eyes...
most of the time.

The camouflage can deceive us

and it's probably
more deceiving to a fish.

After all, octopus camouflage

has been finely honed
by evolution

to exploit shortcomings
in fish vision.

An octopus can still
be seen when moving

and when its camouflage
is switched off.

Just as in any arms race

neither side has
total dominance.

As a last resort

the octopus reaches
into its magician's hat

and pulls out
a cloak of ink.

The long w*r with fish
has produced an octopus

with even greater magic--
the mimic octopus of Indonesia.

It lives exposed on open ground

and survives not
by mimicking its surroundings

but the other creatures
that live here.

Snake eels are
slippery customers

and few fish eat them.

So the octopus mimics them,
hiding its true identity.

Sea snakes are highly venomous.

Fish stay well away.

The octopus is
a remarkable match.

As sea snakes are so dangerous

even a suspicious fish
won't risk a fatal mistake.

The slightest scratch from
the lionfish's spines can k*ll.

Its fins shimmer arning.

The movement is matched
perfectly by the mimic octopus.

The cuttlefish is
a relative of the octopus

so it's hardly surprising
that it has excellent camouflage

and uses this to travel
unnoticed by fish.

Away from the bottom, it even
takes on the shape of weeds

to break up its outline.

But a cuttlefiso use its
skin to hunt.

A creature from the imagination
could hardly be more alien.

The display seems
to mesmerize victims.

Unlike a hunting tiger
stuck with its stripes

or a leopard that
can't change its spots

the cuttlefish attacks
in many disguises.

A skin that can switch between
moving patterns that confuse

and astonishing camouflage
to deceive

must count among evolution's
greatest triumphs.

It could be that cuttlefish

with their extraordinary skin
and superb eyesight

have edged ahead of fish
in this visual arms race.

The scallop only has
light-sensitive cells

gathered in blue pits, but
even these can save its life.

Add a simple lens, and
the owner can resolve detail.

Eyes are such good tools
for escaping and hunting

that they have evolved
many times

into a diverse array
of seeing machines.

These eyes belong to Portia,
a jumping spider

and they're her
main hunting tools.

Portia st*lks with a most
unspider like walk

part of her disguise
when approaching prey.

She hunts other spiders,
identifying them by sight.

Pick the wrong spider

and Portia could end up
as lunch herself.

Argiope has been hunted
by Portia for millions of years

and now has a few tricks
to deal with the deadly menace.

The web is too thin
to take the hunter's weight

so Portia tries to lure
her victim to the edge

by twitching the silk,
mimicking a struggling insect.

But Argiopeis wise to the trick
and bounces violently

a tactic that could catapult
Portia from the web.

Portia seems defeated.

But the master hunter
only appears to give up.

In fact, she's taking
a lengthy detour.

Portia loses sight of her prey
for a time

but still emerges exactly
where she needs to be...

right above Argiope.

The predator takes careful aim

then lowers herself towards
the unsuspecting prey.

This mission only
seems impossible.

Fatally bitten, Argiope
will take time to die.

Portia waits;
her keen vision has triumphed.

Sharp-eyed predators
are everywhere

so potential prey
like moths lie low.

Their ancestors
millions of years ago

were active by day,
but as birds multiplied

moths fled to the night.

For millions of years, moths had
the night skies to themselves

and they filled them.

But around 50 million years ago

one of the greatest arms races
of all time began.

The ancestors of bats
were small mammals

which pounced on insects.

Flying was a ticket

to the vast larder of moths
that filled the night skies.

But how could they find
small, fast-moving prey

without sunlight?

Bats use their ears.

They emit high-intensity
pulses of sound...

then listen for echoes
bouncing back.

Their brains process
these reflections

into a three-dimensional image--

an accurate picture
of their dark world.

Slowing down picture and sound

gives a clearer view
of each encounter.

This sonar is
a brilliant weapon

for finding prey in the dark

making bats successful
around the world.

Bats, though, didn't have it
all their own way for long.

Moths evolved a counterweapon--

a simple ear that could
detect approaching sonar.

An early warning allows the moth
to swerve away.

As bats approach, they increase
their calling rate--

for moths, an emergency cue
to plummet...

though not always to safety.

Many bats are superb fishermen.

It's even possible
that hunting over water

has become a deliberate ploy to snare diving moths.

As insects became better
at detecting sonar

bats required a countermeasure.

In a shadowy corner,
a strange creature is stirring.

Long-eared bats have defeated
the insect ear

by improving their own hearing.

Instead of hunting by sonar

they use their
outrageously large ears

to listen for the sounds
of insects.

Even the tiny beat of moth wings

can be filtered out from
the sound of rushing water.

The bats still use sonar
to avoid branches

but as they approach their prey,
they switch that off

and enter "stealth mode."

Now the bat steers entirely
by the wingbeats of its prey

but the system isn't perfect.

This bat approaches
from the wrong side.

It can hear the moth,
but through the leaf.

A lucky escape for the moth.

Although the bat's hearing
is superb

the method has yet another flaw.

If the moth stays still,
the bat can't locate it.

By maintaining silence,
the moth is perfectly safe.

The hunter is forced to give up.

But sooner or later,
the moth must move

revealing its presence.

Bats have kept pace with their
prey's attempts to evade them

and today the night skies
are full

of specialized moth K*llers.

To avoid them

some moths are taking
the ultimate evasive action.

In Venezuela, moths
are escaping the night.

Active by day, theJosiamoth
can avoid bats completely

but instead,
it must face the birds.

This brings the w*r full circle.

Birds are probably the predators
that drove moths to the night

in the first place.

But the moths returned
to the day with a new trick:

distasteful chemicals advertised
with brilliant colors.

TheJosiastill has remnants

of the ears that once warned it
of approaching bats

but they are of no use
against a sharp eye.

Spit out, the moth may even
escape with its life

but the bird
has learned a lesson.

Most predators learn quickly
to associate colors with danger

resulting in a world
of brilliantly patterned prey.

In Oregon lives
theTarichan newt.

Orange pigment is a warning
that it's more than distasteful.

Each newt contains enough poison

to k*ll 20,000 mice,
or hundreds of people.

In spring
they congregate to mate.

A gathering
of soft-bodied creatures

should be a feast for predators.

But local animals know
the newts are deadly.

And those that don't
are warned off

by a display
of its orange belly.

But why is the newt so poisonous

with enough toxin to k*ll
thousands of crows

when enough to k*ll one
would seem sufficient?

Crows aren't the problem.

Meet the newt's nemesis...

the garter snake.

Long ago, these snakes
evolved a resistance

to low doses of newt poison.

Their prey fought back
producing more poison.

Snakes countered
with greater resistance.

Predator and prey became caught
in an escalating arms race.

Every generation,
the snakes get more resistant

and the newts more poisonous.

This arms race has now reached
a ridiculous level.

The newt spends much
of its energy making poison

and the snake becomes paralyzed
within moments of eating a newt.

To survive the meal

the snake must wind down
its metabolism

while it neutralizes the poison.

Vulnerable to predators, it must
lie still for several hours.

For the snake,
it's not all bad news.

After eating the newt

its tissues are saturated
with toxin

so it becomes poisonous itself.

The newt-eating race
of garter snake

is more brightly colored
than its relatives elsewhere--

possibly to advertise
this secondhand poison.

Poison is a great defense
throughout the animal kingdom

even against master predators
like bobcats.

But poison is expensive to make

so the hognose snake has none
and just pretends.

Cats take the threat
of venom seriously

so a posturing snake
is approached with caution.

There's meat on a snake, but
one meal isn't worth dying for.

The bobcat isn't fooled for long
and launches an attack.

The cat's confidence grows,
and the snake switches tactic

rolling onto its back
and playing dead

very convincingly.

The hognose even reeks of death

as a foul-smelling fluid
oozes from its body.

Many predators avoid corpses
as a precaution against disease.

The cat's interest wanes.

But all the while,
the snake is watching

from the corner of its eye.

Only when the cat has gone

does the snake seem to rise
miraculously from the dead.

It's an incredible display
of deception

but where did this reptile
learn its life-saving trick?

The answer can be found
in the underground nest

of a hognose snake.

As soon as the eggs hatch

the young snakes rush
to leave the chamber.

Such a concentration of yolk and
young often attracts predators.

The last to leave are
the most at risk.

Just hatched, the young snakes
should be an easy target

for a hungry rat.

The rat moves in for the k*ll.

But incredibly,
the snake goes belly up

and shows all the death-feigning
trickery of the adult.

This behavior is programmed
into the genes.

There was no time for the snake
to learn this trick

yet it can deceive a predator
from the moment of hatching.

Snakes don't always succeed.

As they improve
their performance

cats and rats improve their
ability to see through the act.

While the snake's display
deters predators

other displays have evolved
to attract them.

As daylight fades in Puerto Rico

the waters of Mosquito Bay
light up with eerie glows.

Fish sh**t through the water
like fireworks

their outlines
illuminating the night sea.

These are the most glittering
waters on earth.

Like the ghosts of fish

some have great length, others
the flattened form of rays.

Viewed with a special camera

the display
is even more dazzling

but the source is still unclear.

Add infrared light--
invisible to most animals--

and shapes begin
to emerge from the gloom.

Turn up the infrared and
lobsters can be clearly seen--

their antennae like sparklers.

It's not the large animals
that are glowing

but something in the water.

Each spark comes from a single-
celled organism called Noctiluca

that glows when disturbed.

But why should they light up?

Noctiluca are eaten by shrimp.

But surely glowing
will only attract them.

They even continue to glow
once inside the shrimp.

Their light show
doesn't go unnoticed

by the shrimp's predators,
cuttlefish.

Noctiluca's display
starts to make sense.

The cuttlefish can't find shrimp
in complete darkness.

The shrimp is safe
as long as it stays still.

Even with pupils dilated,
the cuttle sees nothing.

But if the shrimp moves

Noctiluca sparkles
and illuminates it.

Now the cuttlefish
can see the shrimp.

The flashing Noctiluca,
like a burglar alarm

gives away
the shrimp's presence.

By attracting cuttlefish
with their flashing lights

Noctiluca protects
itself against shrimp.

The cuttlefish, by predating
shrimp, is Noctiluca's ally.

It's cat-and-mouse,
and the shrimp can't win.

If it stays still,
it can't eat Noctiluca

and if it moves, a glittering
trail attracts cuttlefish.

For shrimp, hunting Noctiluca
is a risky business.

The cuttle gets a meal, but
the real winner is Noctiluca:

Every shrimp removed makes life
safer for the tiny organism.

Noctiluca's "burglar alarm"
saves its life

but each tiny living spark
is unaware

of the defense strategy
programmed into its genes.

Coded into the genes
of another creature

is an even
more elaborate display

critical to its survival.

In the streams of Missouri
lives the Lampsilis mussel

a simple animal with
an extraordinary life cycle.

To reach adulthood, its young
must spend part of their lives

inside a fish,
the large-mouth bass.

To get there, the mussels
must make physical contact--

a difficult task,
as mussels don't swim.

But the bass has a weakness.

It's a voracious predator
of small fish

particularly darters.

Even the slightest wriggle of a
darter's tail will attract bass.

Believe it or not,
the "fish" on the mussel

is an imitation--
a perfect replica

that will lure bass
within striking range.

The mussel can somehow sense
approaching fish

and wriggles its lure faster
to entice them.

If it gets the twitching
just right

the remarkable likeness
should do the rest.

On impact

the mussel squirts its young
into the bass's mouth.

These snap shut on the gills,
like spring-loaded traps.

Here they stay,
drawing blood from the fish

until several weeks later

they drop off as tiny,
fully formed mussels.

Also a favorite prey of the bass
are these striped shiners

and some mussels mimic them.

Considering mussels are blind
and have never seen a shiner

the likeness is incredible.

The eyes, fins and even
the stripe look just right.

Yet the mussel knows nothing
of its own appearance.

These lures have evolved

because bass more often attack
mussels that look like fish

so fishy-looking mussels
leave more descendants.

After millions of years
of blind evolution

this process of selection
has turned mussel flesh

into a lifelike lure.

It takes a good imitation
to fool a bass in clear water

and some of them
are incredible.

This darter mimic even has
a mouth which gulps.

This mussel is the same species

but its curious leopard print
design may not find a taker

and its genes
will go no further.

This lure looks pretty good.

But the bass is unconvinced
and turns it down.

Mussel lures
are constantly improving

but fish are getting ever better
at recognizing fakes.

It's another arms race, and
it's still creating diversity

in the streams of Missouri
to this day.

The battle between individuals

to pass their genes on
to the next generation

has been shaping plants
and animals since life began.

In every corner of the planet

arms races are changing
animal form and behavior.

Understanding arms races

provides a new, dynamic view
of life itself.

Plants are at w*r
with herbivores.

Their defensive spines
are countered

by the elephant's
toughened lips.

The acacia grows upwards
to escape its attackers

but its push for safety
has been countered

by the giraffe's long neck.

The acacia and giraffe
have shaped one another.

The shape and behavior
of all creatures are molded

by other living things.

Nothing evolves in isolation.

Cheetahs created gazelles, just
as gazelles created cheetahs

and even today both
are constantly changing.

Evolution never stands still.

The genes in each generation
will be tested anew.

It's a never-ending race
for survival.

The story of life has been
and always will be

a tale of genes battling
to ensure their line triumphs.