Many animals have extreme physical powers.
Some push their bodies to the limit.
0thers tolerate the harshest conditions on earth.
Escaping a bush fire, a cheetah is the fastest animal on foot.
At 100 kilometres an hour, its muscles are starved of oxygen,
its temperature soars to near lethal levels.
Like other animals with extreme powers,
it takes physical endurance to the edge.
0n this journey, we explore the life found in extreme environments.
Microscopic life forms that can endure harsh conditions in space
often invade our homes.
Riding the wind, the spores of the pinhead fungus
colonise almost every corner of earth.
When they find perfect conditions, they quickly exploit them.
Invading mycelia reduce fruit to pulp.
The next generation of spores develops in just a few days.
Housed in capsules, they wait for liftoff.
Young money spiders also tolerate extreme conditions.
To disperse, they climb to the highest points
and wait for a gust of wind.
(TV) T minus ten, nine, eight, seven,
six, five, four, three,
two, one, zero.
Ignition.
Liftoff. Liftoff 30 minutes after the hour.
(Cat yowls)
The spores and spiders have begun a journey
that will take them to new worlds.
Buoyed by air currents,
they´re transported high into the atmosphere.
Here, they´ll encounter some of the most extreme environments.
Higher forms of life also tolerate these high-altitude conditions.
The Himalayas.
Ten kilometres up, no life should survive.
Unidentified flying objects demand investigation.
(Geese honking)
Migrating bar-headed geese
ride the 200 kilometres-an-hour winds that blow at this altitude.
Here, pilots breathe pure oxygen.
Geese extract their oxygen from the thin air.
0nce every second they take a breath.
Each minute their heart pumps 400 times.
Special blood cells absorb every trace of oxygen.
At minus 55, only the heat from their exertion
stops them freezing solid.
Bar-heads breathe at high altitude
more efficiently than any other bird.
The ocean presents air-breathing animals with a different extreme.
Sea lions are natural divers.
We push our bodies to the limit in an effort to compete.
Free divers meditate to prepare for the challenge ahead.
Ten metres down and the pressure doubles.
At 60 metres, the pressure can squash the diver´s lungs
enough to tear them from his ribcage.
The sea lion´s chest is designed to collapse.
Both man and sea lion lower their metabolism to save oxygen
and drop their heartbeats to below ten a minute.
The human depth record is 134 metres.
Sea lions double this with ease.
Their blood holds five times more oxygen.
2,000 metres down, squid provide food for the elephant seal.
It uses its two-ton body as a huge oxygen store and can remain submerged for two hours.
It stays active even though its heart beats just four times a minute.
The deepest diving mammal, the sperm whale,
reaches two and a half kilometres.
Its lungs are proportionately smaller than ours,
but its muscles act as a huge oxygen store.
Four kilometres down, volcanic vents erupt from the sea bed.
These black smokers spew out toxic waste
and yet life is found.
Deep-sea shrimps graze bacteria
that thrive near the superheated vents.
Mats of bacteria harness heat and chemical energy.
The first forms of life, they survive boiling and crushing pressures.
Journey into the earth
and we may find more bacteria than at the surface.
Three and a half kilometres down,
bacteria are brought to light for the first time.
Surviving huge pressures and heat,
each individual can live for a thousand years.
They eat nothing but rock.
In this South African mine, they also play a unique role.
(Siren wails)
Bacteria living here are natural alchemists.
They create deposits of gold.
As they break down the mineral ores,
the bacteria attract molecules of gold to their surface.
0ver millions of years, the gold builds up
to form a glittering seam.
The world of extremes is also inhabited by fairies.
(Echoing voices )
Smaller than a grain of sand, the eggs of the fairy shrimp
may wait 10,000 years for life-giving water.
They have evolved to survive prolonged exposure
to the intense heat of southern Africa.
This must be their severest test of survival.
Besides their tough outer coating,
the embryo´s cells are protected by chemical heat shields.
As the water cools, a miraculous transformation begins.
The fairies hatch.
These crustaceans are the only animals that can withstand boiling.
This just-add-water technique
allows the fairy shrimp to exploit pools
that may appear only once every ten years.
But predators, like the prehistoric-looking Triops,
also hatch from hard-boiled eggs.
(Shouting)
In the Middle East, some plants are consumed
by a different kind of heat.
The aromatic cistus bush gives off inflammable vapours in sunlight.
0n still days, these shroud the plant,
turning it into a living petrol bomb.
0ne spark is enough to ignite.
The bush may burn, but so do its competitors.
This clears the ground for the next generation.
As the seeds are freed, they crack in the heat, ready for germination.
The biblical story of the burning bush may have arisen
from this natural miracle.
In Florida, there´s a creature with a passion for fire.
The fire beetle can sense infrared rays beyond our visual range
that are given off by forest fires.
The signal radiates 80 kilometres,
drawing the solitary beetles together
to seek the source of the fire.
As Florida´s Division of Forestry dampens the inferno,
the females´ scent inflames the interest of the males.
Spurred on by the females, there´s hot competition to be first.
The burnt wood is a vital prize.
It´ll provide a home and food for the next generation of fire beetles.
Water can provide a refuge from temperature extremes.
While it´s there.
Southern Africa is frequently ravaged by severe droughts.
For a fish out of water, death is usually inevitable.
But these fish are not gulping air in vain.
Their swim bladder forms a crude lung,
allowing them to take in oxygen directly from the air.
The lungfish escapes the desiccating heat by burrowing.
It swallows the mud to excavate a chamber,
passing it out again through the gills.
Then it coats itself in mucus.
As the mucus dries, it forms an impervious body bag
that seals off the fish from the drought.
River mud makes a secure chamber for the lungfish,
but it´s equally suitable for making bricks.
As things go from bad to worse,
the lungfish shuts down and waits for conditions to improve.
Central Australia also suffers prolonged droughts.
Beneath the dried lake bed, other animals are buried alive.
The desert frog can survive entombed for seven years.
It sheds layers of skin that form a waterproof barrier
which prevents the frog drying out.
Above, the search for water continues.
The thorny devil can survive for years without drinking.
Black ants provide all the moisture it needs, and it eats nothing else.
There are other ways of quenching thirst in the desert.
The frog´s bladder holds a reservoir of drinking water,
providing a good emergency supply for Aborigines.
In the desert, little is wasted.
The thorny devil has a unique way of collecting water.
Capillary action.
Its skin sucks up the liquid like blotting paper.
A darkening band traces the water´s progress across the skin
until it reaches the eyes and mouth.
A network of channels directs the water to the mouth.
In this way, the lizards drink the morning dew
that forms on the desert sand.
Even in Africa, droughts must end.
The lungfish may wait four years before the rainwater arrives
to release it from suspended animation.
By the end of the dormant period,
the lungfish has started to process its muscles as food.
But enough power remains in them to drag the fish back to water.
Many animals use dormant periods to escape extreme conditions,
particularly the cold.
In Manitoba, Canada, thousands of red-sided garter snakes
emerge from their winter hibernation.
They live further north than any other snake.
The summers are short here, and it´s a race to mate.
The larger females are overwhelmed by males
which may outnumber them a thousand to one.
They live dangerously, for the winter weather can quickly return.
The drop in temperature cools their passion
and they race back to their dens to escape the approaching freeze.
Not all make it. Cold-blooded reptiles become immobilised
as the temperature drops.
Trapped in an icy grip, the water in their bodies starts to freeze.
They turn into ice sculptures.
With the dawn thaw, a resurrection slowly begins.
Red-sided garter snakes are the only snakes that can survive freezing.
While the rest of their bodies freeze solid,
their vital organs are protected by a natural antifreeze.
The black stripes act as solar panels to speed defrosting.
Soon the heat of passion returns, as the males risk the cold to mate.
Even further north, the polar bear regularly withstands minus 45 degrees,
insulated by its thick coat.
In a thermal image that depicts temperature as colour,
its coat is as blue as the cold background.
The bears show so little heat escaping, they almost vanish.
In late summer, as they wait for the freeze,
the bears are actually in danger of overheating.
Protected by clothing, heat can only escape
from the scientist´s face and hands.
The bear leaks body heat only from here too.
It has such perfect insulation, at rest it loses no more heat
than a 200-watt light bulb does.
Like the heat print on the weather balloon,
the only trace left by the bear is a heat print on the ground.
The bears have starved for six months,
longer than any other land mammal could tolerate.
To survive, it conserves energy by dropping its body temperature
to levels lethal to us.
If there´s a chance of a meal, they´ll take it.
It can smell food from as much as 30 kilometres away.
The polar bear is one of the few predators
that will deliberately hunt a man.
(Growling)
Tripwires and flares
prove their worth.
Weather balloons probe earth´s other coldest region.
Five kilometres up, our money spiders exploit high-altitude winds
to continue their journey.
At minus 30, ice forms over their surface,
but their bodies are protected by a natural antifreeze.
80 kilometres up, above the ozone layer,
our spores from the strawberries survive extreme cold
and damaging ultraviolet rays.
Gravity has little effect on these tiny spores,
and, repelled by the earth´s electric field,
they could be launched into space.
In this infinite vacuum, it´s minus 90.
0nly modern technology can take us here.
Although fungal spores have yet to be recorded here,
they are capable of surviving these conditions.
Living for 10,000 years, they make the perfect space travellers
to colonise new worlds.
0n earth, with the change in temperature and pressure,
our defrosting spiderlings descend.
They have crossed oceans to settle in their new world.
0ur quest for extraterrestrial life is helped
by a growing understanding of the earth´s extreme organisms.
The harsh conditions these creatures endure
make the probability of life in space a certainty.
0n our next journey,
Supernatural explores the hidden forces of nature.
(Geese honking)