盒子的英文BBC经典-《行星地球》英文解说词(全集)

2021年1月20日发(作者：elites)

行星地球英文解说词


第
1
集

PLANET EARTH From Pole to Pole

A hundred years ago there were one and a half billion people on Earth.
Now, over six billion crowd our fragile planet Earth. But even so, there
are
still places
barely
touched by
humanity.
This
series
will take to the
last wildernesses and show you the planet Earth and its wildlife as you
have
never
seen
them
before.
Imagine
our
world
without
sun.
Male
Emperor penguins are facing the nearest that exists on planet Earth Earth
-
winter
in
Antarctica.
It's
continuously
dark
and
temperatures
drop
to
minus
seventy
degrees
centigrade.
The
penguins
stay
when
all
other
creatures have fled because each guards a treasure: a single egg rested on
the top of its feet and kept warm beneath the downy bulge of its stomach.
There
is
no
food
and
no
water
for
them,
and
they
will
not
see
the
sun
again for four months. Surely no greater ordeal is faced by any animal. As
the sun departs from the Antarctic it lightens the skies in the far north. It's
March and light returns to the high Arctic, sweeping away four months of
darkness.
A
polar
bear
stirs.
She has
been
in
her
den
the
whole
winter.
Her
emergence
marks
the
beginning
of
spring.
After
months
of
confinement underground she toboggans down the slope. Perhaps to clean
her fur, perhaps for sheer joy. Her cubs gaze out of their bright new world

1

for the very first time. The female calls them, but this steep slope is not
the easiest place to take your first steps. But they are hungry and eager to
reach their mother, who's delayed feeding them on this special day. Now
she
lures
them
with
the
promise
of
milk,
the
only
food
the
cubs
have
known since they were born deaf and blind beneath the snow some two
months ago. Their mother has not eaten for five months and has lost half
her body weight. Now she converts the last of her fat reserves into milk
for
her
cubs.
The
spring
sun
brings
warmth
but
also
a
problem
for
the
mother. It starts to melt the sea ice. That is where she hunts for the seal
she needs to feed her cubs. And she must get there before the ice breaks
up. For now though it's still minus thirty degrees and the cubs must have
the shelter of the den. It's six days since the bears emerged and spring is
advancing
rapidly.
But
even
now
blizzards
can
strike
without
warning.
Being
so
small,
the
cubs
are
easily
chilled
and
they
will
be
more
comfortable resting in the den. But their mother must keep them out and
active.
She's
becoming
weak
from
hunger
and
there's
no
food
on
these
nursery slopes. The sea ice still holds firm, but it won't last much longer.
Day 10, and the mother has led her cubs a mile from the den. It's time to
put them to the test. They've grown enormously in confidence, but they
don't
have
their
mother's
sense
of
urgency.
At
last
it
seems
that
they're
ready for their journey and they're only just in time, for a few miles from
the coast the ice is already splitting. Now the mother can start hunting for

2

the seals they must have, but she's leading her cubs into a dangerous new
world.
Nearly
half
of
all
cubs
die
in
their
first
year
out
on
the
ice.
Summer brings 24 hours of sunlight and the thawing shifting landscape.
Further
south
the
winter
snows
have
almost
cleared
from
the
Arctic
tundra.
Northern
Canada's
wild
frontier.
Here
nature
stages
one
of
her
greatest
dramas
-
Every
year
three
million
caribou
migrate
across
the
Arctic
tundra.
The
immensity
of
the
herd
can
only
be
properly
appreciated
from
the
air.
Some
herds
travel
over
2,000
miles
a
year
in
search of fresh pastures. This is the longest overland migration made by
any animal. They're constantly on the move. Newborn calves have to be
up
and
running
the
day
they
are
born.
But
the
vast
herds
do
not
travel
alone. Wolves. Packs of them, eight to ten strong, shadow the migration.
And
they
are
hungry.
It's
the
newly
born
calves
that
they
are
after.
Running directly at the herd is a ploy to generate panic. The herd breaks
up
and
now
it's
easier
to
target
an
individual.
In
the
chaos
a
calf
is
separated from its mother. The calf is young, but it can outrun the wolf if
only it manages to keep its footing. At this stage the odds are even - either
the
caribou
will
make
a
mistake
or
after
a
mile
the
wolf
will
give
up.
Midsummer on the tundra and the sun does not set. At these latitudes the
sun's rays are glancing and not enough of their energy reaches the ground
to enable trees to grow. You'll need to travel 500 miles south from here
before
that
is
possible.
These
stunted
shrubs
mark
the
tree
line
-
the

3

beginning of the boreal forest - the taiga. The needle-shaped leaves of the
conifers are virtually inedible so this forest supports very little animal life.
It's a silent place where the snow is unmarked by footprints. In the Arctic
winter
snow
forms
a
continuous
blanket
across
the
land.
But
as
spring
creeps up from the south the taiga is unveiled. This vast forest circling the
globe
contains
a
third
of
all
the
trees
on
Earth
and
produces
so
much
oxygen it changes the composition of the atmosphere. As we travel south
so
the
sun's
influence
grows
stronger
and
at
50
degrees
of
latitude
a
radical
transformation
begins.
Summers
here
are
long
enough
for
broadleaf trees to replace conifers. Broadleaves are much easier to eat and
digest so now animals can collect their share of the energy that has come
from the sun. It's summer and these forests are bustling with life. But the
good
times
will
not
last.
Broad
leaves
must
be
shed
in
winter
for
their
damage by frost. As they disappear, so the land becomes barren with little
for
animals
to
eat.
The
inhabitants
must
migrate,
hibernate,
or
face
months of near starvation. The Amur leopard - the rarest cat in the world.
Here, in the deciduous forests of eastern Russia the winter makes hunting
very
difficult.
Pray
animals
are
scarce,
and
there's
no
concealing
vegetation. The cub is a year old and still dependent on its mother. Deer
are
frequent
casualties
of
the
harsh
winter
and
these
leopards
are
not
above
scavenging
from
a
corpse.
African
leopards
could
never
survive
here,
but
the
Russian
cats
have
thick
fur
to
shield
them
from
the
cold.

4

There
are
only
forty
Amur
leopards
left in the
wild and that number
is
falling.
Like
so
many
creatures,
the
cats
have
been
pushed
to
the
very
edge
of
extinction
by
hunting
and
the
destruction
of
their
habitat.
The
Amur leopard symbolises the fragility of our natural heritage. The future
of an entire species hangs on survival of a tiny number of mothers like
this one. All animals, rare or common, ultimately depend for their energy
on
the
sun.
In
Japan
the
arrival
of
the
cherry
blossom
announces
the
beginning of spring. The sun's energy brings colour to the landscape. The
earth, as it makes its annual journey around the sun, spins on a tilted axis.
And
it's
this
tilt
that
creates
the
seasons.
The
advance
of
the
seasons
brings constant change. As the sun's influence diminishes in the north, so
the deciduous forests of America begin to shut down losing their leaves in
preparation
for
the
dark
cold
months
ahead.
One
season
hands
over
to
another.
Some
organisms
thrive
on
decay,
but
most
must
make
special
preparations
for
winter
and
a
life
with
little
sun.
Whole
populations
of
animals
are
now
forced
to
travel
great
distances
in
pursuit
of
food
and
warmth. 300,000 Baikal teal gather to escape from the Siberian winter by
migrating south to Korea - the world's entire population in a single flock.
But there are parts of the world that have no seasons. In the tropics the
sun's
rays
strike
the
earth
head
on
and
their
strength
is
more
or
less
constant all year round. That is why the jungle grows so vigourously and
supports
so
much
life.
This
forest
covers
only
3
percent
of
the
planet's

5

surface, but it contains more than 50 percent of all its plants and animals.
The canopy is particularly rich. There are monkeys, birds and millions of
species of insects, exactly how many we have no idea. The character of
the
forest
changes
as
we
descend,
becoming
ever
darker
and
damper,
favouring different kinds of animals and plants. Less than 2 percent of the
sunlight reaches the floor, but even here there is extraordinary variety. In
the great island of New Guinea there are 42 different species of birds of
paradise,
each
more
bizarre
than
the
last.
This
forest
is
so
rich
that
nourishing
food
can
be
gathered
very
quickly.
That
leaves
the
male
six-plumed bird of paradise with time to concentrate on other matters like
tidying
up
his
display
area.
Everything
must
be
spick
and
span.
All
is
ready.
Very
impressive,
but
no
one
is
watching.
The
superb
bird
of
paradise calls to attract a female. And he has more luck. But what does he
have to do to really impress her? She retires to consider her verdict. It's
hard not to feel deflated when even your best isn't good enough. The sun
influences life in the oceans just as it does on land. Its richest parts are
those
where
waves
and
currents
bring
fertilising
nutrients
to
surface
waters that are bathed in sunlight. The seas off the Cape in South Africa
have this magic recipe and are hugely productive. Summer is the time of
plenty and it's now that the seals start to breed. The strike of a great white
shark
lasts
a
mere
second.
Slowing
it
down
forty
times
reveals
the
technique and immense strength of this massive predator. If surprise fails,

6

there will be a chase. The shark is faster on a straight course but it can't
turn as sharply as the seal, its agility versus power. Once the seals
have
finished breeding the giant sharks will move on. It's now becoming clear
that great whites migrate thousands of miles across the oceans to harvest
seasonal abundances in different seas. The sun, beating down on tropical
waters,
powers
the
weather
systems
of
the
globe.
Moisture
evaporates
from
the
warming
ocean
and
rises
to
create
great
storms.
The
winds
generated
out
at
sea
sweep
inland
across
the
continents.
As
they
travel
across the Sahara they create the biggest of all sand storms blowing sand
halfway round the world to fertilize the Amazon jungle. Winds blowing
across the Indian Ocean collect moisture and sweep northwards towards
the Himalayas. As the air rises, so it cools. The water it carries condenses
into clouds and then falls as the life giving rains of the monsoon. So air
currents
powered
by
the
sun
carry
wet
air
to
the
middle
of
continents.
Without water there can be no life, but its distribution over the land is far
from
even.
Deserts
cover
one
third
of
the
land's
surface
and
they're
growing bigger every year. This is the Kalahari Desert in Southern Africa.
It's
the
dry
season
and
thousands
of
elephants
have
started
to
travel
in
desperate
search
for
water.
All
across
Southern
Africa
animals
are
journeying for the same reason. Buffalo join the great trek. Nowhere else
on Earth are so many animals on the move with the same urgent purpose.
They're all heading for the swamps of the Okavango, a vast inland delta.

7

At the moment it is dry, but water is coming. The travellers are hampered
by
dangerous
dust
storms.
Females
and
calves
can
easily
get
separated
from the main herd. For this pair sanctuary lies in the patch of woodland
a
few
miles
ahead.
They
can't
rest
until
they
reach
it.
The
main
has
already got there safely. Finally, the stragglers emerge from the dust. The
exhausted
calf
is
still
blinded
by
sand.
Its
mother
does
everything
possible to help it. The storm is now subsiding, but not all the elephants
have been so lucky. One youngster has got lost. Thirsty and exhausted, it
follows the tracks of its mother, but sadly in the wrong direction. At the
peak of the dry season in the Kalahari water arrives in the Okavango. It
fell
as
rain
a
thousand
miles
away
in
the
highlands
of
Angola
and
has
taken nearly five months to reach here. The water drives out insects from
the parched ground, which are snapped up by plovers. Catfish, travelling
with the flood, collect any drowning creatures the birds have missed. It's
a seasonal feast for animals of all kinds. Birds are the first to arrive in any
numbers - water cranes, then black storks. Behind the birds come buffalo.
After
weeks
of
marching
their
trek
is
coming
to
an
end.
As
the
water
sweeps into the Okavango a vast area of the Kalahari is transformed into
a fertile paradise. Nowhere on our planet Earth is the life giving power of
water so clearly demonstrated. The Okavango becomes criss-crossed with
trails as animals move into its heart. The new arrivals open up paths like
arteries along which water flows, extending the reach of the flood. This is

8

an Africa rarely seen - a lush water world. Some creatures are completely
at home here. These are lechwe - antelope with hooves that splay widely,
enabling them to move its speed through the water. For others the change
is
far
less
welcome.
Baboons
are
somewhat
apprehensive
bathers.
The
water brings a season of plenty for all animals. Hunting dogs. These are
now
among
the
rarest
of
Africa's
mammals,
but
then
nonetheless
the
continent's most efficient predators. Their secret is teamwork. Impala are
their favourite prey. They start to hunt and the pack splits up. An aerial
viewpoint gives a new insight into their strategy. As the dogs approach
their prey they peel off to take up separate positions around their target.
They seem to form a cordon around the impala. Moving in total silence
they take up their positions. Those ears can detect the slightest rustle. The
hunt
is
on.
Three
dogs
close
in
on
one
impala.
Missed.
The
lead
dog
drives the impala towards the hidden flankers. Anticipating their line the
leader cuts the corner and joins a flanker for the final assault. It's all or
nothing. One on one. The dog has stamina, the impala has speed. Leaping
into the lake is an act of desperation - impala can barely swim. The dogs
know their prey must come out or drown - now it's a waiting game. The
rest of the pack are calling. They've made a kill in the forest and this is an
invitation to join in the meal. The impala is in luck. A pack this size kills
once
a day
and
everything is shared.
And
this impala is reprieved.
The
elephants
are
nearing
the
end
of
their
long
journey.
After
weeks
of

9

marching
they're
desperately
tired.
The
matriarch
can
smell
water
and
encourages the herd to make one last effort. The youngsters are exhausted
but
their
mothers
have
made
this
journey
before
and
they
know
that
they're close to water. After many hundreds of miles they've arrived. The
lives of these elephants are dominated by the annual rhythm of wet and
dry, a seasonal cycle created by the sun. At the southern end of the earth,
after
four
months
of
total
darkness,
the
sun
once
more
rises
over
Antarctica. Now at last the Emperor penguins abandon their huddle. The
males
are
still
carrying
the
precious
eggs
that
they've
cherished
throughout
the
Antarctic
winter.
With
the
returning
sun
the
eggs
hatch.
Other birds have not even arrived. but the Emperors by enduring the long
black
winter
have
given
their
chicks
a
head
start.
These
youngsters
are
now ready and eager to make the most of the brief Antarctic summer.

第
2
集

PLANET EARTH Mountains




Human beings venture into the highest parts of our planet at their peril.
Some might think that by climbing a great mountain they have somehow
conquered it, but we can only be visitors here. This is a frozen alien world.
This is the other extreme - one of the lowest hottest places on Earth. It's

10

over a hundred metres below the level of the sea. But here a mountain is
in
gestation.
Pools
of
sulphuric
acid
are
indications
that
deep
underground there are titanic stirrings. This is the Danakil Depression in
Ethiopia,
lying
within
a
colossal
rent
of
the
earth's
surface
where
giant
land masses are pulling away from one another. Lava rises to the surface
through this crack in the crust creating a chain of young volcanoes. This
one,
Erta
Ale,
is
today
the
longest
continually
erupting
volcano
on
the
planet,
a
lake
of
lava
that
has
been
molten
for
over
a
hundred
years.
These same volcanic forces also created Ethiopia's highlands. 70 million
years ago this land was just as flat and as deep as the Danakil Depression.
Molten lava rising from the earth's core forced up a huge dome of rock
500 miles wide, the roof of Africa. Over millennia, rain and ice carved the
rock
into
a
landscape
of
spires
and
canyons.
These
summits,
nearly
3
miles
up,
are
home
to
some
very
remarkable
mountaineers
Gelada
baboons. They are unique to the highlands of Ethiopia. The cliffs where
they
sleep
are
for
expert
climbers
only,
and
Gelado
certainly
have
the
right
equipment.
the
strongest
fingers
of
any
primate
and
an
utterly
fearless disposition. But you need more than a head for heights to survive
up
here.
A
day
in
a
Gelado's
life
reveals
how
they've
risen
to
the
challenge. For all monkeys morning is grooming time, a chance to catch
up
with
friends.
But,
unlike
other
monkeys,
Gelados
chatter
constantly
while they do it. It's a great way to network while your hands are busy.

11

But
these
socials
can't
go
on
for
too
long.
Gelados
have
a
busy
daily
schedule and there's work to be done. Most monkeys couldn't live up here.
There's
no
food
and
few
insects
to
feed
on.
But
Gelados
are
unique
they're the only monkeys in the world that live almost entirely on grass.
They live in the largest assemblies formed by any monkeys. Some groups
are 800 strong and they crop the high meadows like herds of wildebeest.
The Gelados graze alongside Walia ibex, which are also unique to these
highlands. These rare creatures are usually very shy but they drop their
guard when the Gelados are around. You might expect that grazers would
avoid
each
other's
patch
but
this
is
a
special
alliance
from
which
both
partners benefit. It's not so risky to put your head down if others are on
the
lookout.
Ethiopian
wolves
-
they
won't
attempt
an
attack
in
broad
daylight. But at dusk the plateau becomes a more dangerous place. With
the grazing largely over there's a last chance to socialise before returning
to the sleeping cliffs. An early warning system puts everyone on the alert.
Their
day
ends
as
it
began,
safe
on
the
steep
cliffs.
The
Ethiopian
volcanoes
are
dormant,
but
elsewhere
others
still
rage.
V
olcanoes
form
the backbone of the longest mountain chain on our planet - the Andes of
South
America.
This
vast
range
stretches
5,000
miles
from
the
Equator
down
to
the
Antarctic.
It
formed
as
the
floor
of
the
Pacific
Ocean
slid
beneath the South American continent, buckling its edge. At the southern
end
stand
the
mountains
of
Patagonia.
It's
high
summer,
but
the
Andes

12

have
the
most
unstable
mountain
weather
on the planet
and storms
can
erupt
without
warning.
Temperatures
plummet
and
guanacos
and
their
newborn young must suddenly endure a blizzard. Truly, all seasons in one
day...
A
puma
-
the
lion
of
the
Andes.
Pumas
are
usually
solitary
and
secretive. To see a group walking boldly in the open is extremely rare. It's
a
family
-
a
mother
with
four
cubs.
She
has
just
one
brief
summer
in
which
to
teach
them
their
mountain
survival
techniques.
Rearing
four
cubs
to
this
age
is
an
exceptional
feat,
but
she
does
have
an
excellent
territory, rich in food and water. Although the cubs are now as large as
their mother, they still rely on her for their food. It will be another year
before the cubs can hunt for themselves. Without their mother's skill and
experience
they
would
never
survive
their
first
winter.
Battered
by
hurricane force winds, these slopes are now lifeless. Further north, they
hold other dangers. Moving at 250 miles an hour, an avalanche destroys
everything
in
its
path.
In
the
American
Rockies
a
100,000
avalanches
devastate the slopes every winter. This huge mountain chain continues the
great spine that runs from Patagonia to Alaska. The slopes of the Rockies,
bleak
though
they
are,
provide
a
winter
refuge
for
some
animals.
A
mother
grizzly
emerges
from
her
den
after
six
months'
dozing
underground.
Her
two
cubs
follow
her
and
take
their
first
steps
in
the
outside
world.
These
steep
slopes
provide
a
sanctuary
for
the
cubs.
A
male bear would kill and eat them given the chance. But big animals find

13

it difficult to get about here. Males may be twice the size of a female and
even she can have problems. Her cubs, however, make light of the snow
and
of
life
in
general.
But
the
mother
faces
a
dilemma:
it's
six
months
since she last fed and her milk is starting to run dry. She must soon leave
the
safety
of
these
nursery
slopes
and
lead
her
cubs
away
from
the
mountain.
If
she
delays,
the
whole
family
will
risk
starvation.
Summer
reveals the true nature of the Rockies. Stripped of snow, the peaks bear
their
sculpted
forms.
Only
now
can
mountaineers
reclaim
the
upper
reaches. Two miles up the crumbling precipices seem devoid of life. But
there are animals here - a grizzly bear. It seems to be an odd creature to
find
on
these
high
rocky
slopes.
It's
hard
to
imagine
what
could
have
attracted it here. At this time of the year bears should be fattening up for
the winter. Yet they gather in some numbers on these apparently barren
slopes. They're searching for a rather unusual food - moths. Millions have
flown up here to escape the heat of the lowlands and they're now roosting
among
the
rocks.
Moths
may
seem
a
meager
meal
for
a
bear,
but
their
bodies are rich in fat and can make all the difference in a bear's annual
struggle for survival. Another battle is being waged here but on a much
longer
timescale.
These
loose
boulders
are
the
mountain's
crumbling
bones.
The
Rockies
are
no
longer
rising
but
slowly
disintegrating.
All
mountains everywhere are being worn down by frost, snow and ice. The
Alps were raised some 15 million years ago as Africa, drifting northwards,

14

collided
with
the
southern
edge
of
Europe.
These
spires
are
the
eroded
remains
of
an
ancient
seabed
that
once
stretched
between
the
two
continents. But these are just the Alpine foothills. The range at its centre
rises
to
3
miles
high
and
is
crowned
with
permanent
snows.
The
Matterhorn, its summit too steep to hold a snow field. Mont Blanc
- the
highest peak in Western Europe. The distinctive jagged shapes of the Alps
were
carved
by
those
great
mountain
sculptors
-
the
glaciers.
Immense
rivers
of
moving
ice,
laden
with
rock,
grind
their
way
down
the
mountains, gouging out deep valleys. They're the most powerful erosive
force on our planet. A moulin - a shaft in the ice opened by melt water as
it plunges into the depths of the glacier. Like the water running through it,
the
ice
itself
is
constantly
moving,
flowing
down
the
valley
with
unstoppable
force.
Alpine
glaciers
may
seem
immense,
but
they're
dwarfed by those in the great ranges that divide the Indian subcontinent
from Tibet. This is the boulder strewn snout of the giant Baltoro glacier in
the Karakoram mountains of Pakistan. It's the biggest mountain glacier on
Earth - 43 miles long and over 3 miles wide. This huge ice-filled valley is
so large it's clearly visible from space. This is the greatest concentration
of peaks over 5 miles high to be found anywhere on Earth. They're the
most dangerous mountains of all. K2 and her sister peaks have claimed
more
lives
than
any
others.
The
peaks
here
rise
so
precipitously,
the
glaciers
are
so
steep
and
crevassed
that
few
except
the
most
skilled

15

mountaineers can penetrate these ranges. Markhor gather for their annual
rut. Males must fight for the right to breed, but on these sheer cliffs any
slip
by
either
animal
could
be
fatal.
A
snow
leopard
-
the
rarest
of
Himalayan animals. It's a female returning to her lair. These are the first
intimate images of snow leopard ever filmed in the wild. She greets her
one year old cub. Her den is well chosen. It has exceptional views of the
surrounding cliffs. On these treacherous slopes no hunter other than the
snow
leopard
would
have
a
chance
of
catching
such
fragile
prey.
A
female
with
young
makes
an
easier
target.
Her
large
paws
give
an
excellent grip and that long tail helps her balance. Silently she positions
herself
above
her
prey.
She
returns
with
nothing.
Golden
eagles
patrol
these cliffs in search of the weak or injured. With a 2 metre wing span
this bird could easily take a young markhor. Eagles hunt by sight and the
thickening veil of snow forces them to give up. For the leopard the snow
provides
cover
and
creates
an
opportunity.
The
worsening
weather
dampens
the
sound
of
her
approach
allowing
her
to
get
within
striking
distance. It was an act of desperation to try and catch such a large animal.
Wolves have made a kill giving other hunters a chance to scavenge. The
worst
of
the
blizzard
brings
success
for
the
snow
leopard,
but
having
descended so far to make the kill she has a grueling climb to get back to
her lair. The cub must be patient. It'll be a year before it has the strength
and skill to kill for itself on these difficult slopes. The snow leopard is an

16

almost
mythical
creature,
an
icon
of
the
wilderness,
an
animal
few
humans
have
ever
glimpsed
for
its
world
is
one
we
seldom
visit.
The
Karakoram lie at the western end of a range that stretches across a tenth
of our planet - the Himalayas. These, the highest mountains of the world,
like other great ranges, were created by the collision of continents. Some
50 million years ago India collided with Tibet thrusting up these immense
peaks,
which
are
still
rising.
This
vast
barrier
of
rock
and
ice
is
so
colossal
it
shapes
the
world's
climate.
Warm
winds
from
India,
full
of
moisture, are forced upwards by the Himalayas. As the air rises so it cools,
causing
clouds
to
form
and
the
monsoon
is
born.
At
high
altitudes
the
monsoon rains fall as snow. Here, at the far eastern end of the range in
China,
one
inhabitant
endures
the
bitter
winters
out
in
the
open.
Most
other bears would be sleeping underground by now, but the giant panda
can't fatten up enough to hibernate. Its food, bamboo, on which it totally
relies has so little nutritional value that it can't build up a store of fat like
other bears. Most of the creatures here move up or down the slopes with
the
seasons
but
the
panda
is
held
captive
by
its
diet
for
the
kind
of
bamboo it eats only
grows at this altitude. But these forests hold fewer
challenges for the more mobile. The golden snap-nosed monkey, like the
giant panda, lives only in China. Their thick fur allows them to survive at
greater altitudes than any other monkey and when the cold bites they have
these
upper
slopes
to
themselves.
Even
if
you
have
a
warm
coat
it

17

apparently
helps
to
surround
yourself
with
as
many
layers
as
possible.
But at least these monkeys have a choice
- if they tire of tree bark
and
other
survival
food
they
can
always
descend
to
lower
warmer
altitudes
and
not
return
there
till
spring.
As
the
snows
retreat
trees
come
into
bloom. Cherry blossom. Rhododendrons - here in their natural home they
form great forests and fill the landscape with the covers of a new season.
These forests are a host to a rich variety of springtime migrants. Beneath
the blooms - another display. It's the mating season for oriental pheasants,
Himalayan
monal,
tragopan
and
blood
pheasant.
Musk
deer
make
the
most of a short flash of spring foods. This male smells a potential mate.
The red panda, rarely glimpsed in the wild. It was once considered a kind
of
raccoon,
but
is
now
believed
to
be
a
small
mountain
bear.
By
midsummer its larger, more famous relative, has retreated into a cave. A
giant panda nurses a tiny week old baby. Her tender cleaning wards off
infection. She won't leave this cave for three weeks, not while her cub is
so
utterly
helpless.
Progress
is
slow
for
milk
produced
on
a
diet
of
bamboo is wretchedly poor. Four weeks old and the cub is still blind. Its
eyes do not fully open until three months after birth, but the chances of
the cub reaching adulthood are slim. The struggle of a giant panda mother
to raise her cub is a touching symbol of the precariousness of life in the
mountains.
On
the
highest
summits
of
our
planet
nothing
can
live
permanently. The highest peak of all, Mount Everest, five and a half miles

18

above sea level and still rising - the roof of our world. Of those humans
who've tried to climb it one in ten have lost their lives. Those that succeed
can stand for only a few moments on its summit. The Nepalese call it 'a
mountain
so
high
no
bird
can
fly
above
it.'
But
each
year
over
50,000
demoiselle cranes set out on one of the most challenging migrations on
Earth. To reach their overwintering grounds in India they must cross the
Himalayas. By late morning ferocious winds are roaring past the peaks.
The
cranes
must
gain
height
to
avoid
the
building
storm.
They've
hit
serious turbulence. They must turn back or risk death. A new day and a
new opportunity. The flock stay in close contact by calling one another.
Weak from lack of food and water, they use thermals, rising columns of
warm
air,
to
gain height.
For
many
this
is
their
first
journey
across the
Himalayas. For some, it will be their last. The golden eagles have been
expecting them. The eagles work in pairs to separate a young crane from
the
flock.
It
escapes
the
touches
of
one,
and
is
caught
by
another.
But
even
a
young
crane
is
a
heavy
prize
and
the
eagle
has
to
struggle
to
control it. The mother can wait no longer - this is a desperate race against
worsening
weather.
The
rest
of
the
flock
battle
on.
In
the
ascent
every
wing
beat
becomes
an
exhausting
struggle.
At
last
they
are
over
the
highest barrier that lies in their way. But like all who visit the world of the
high mountains they dare not linger.


19

第
3
集

PLANET EARTH Freshwater




Only
3
percent
of
the
water
on
our
planet
is
fresh.
Yet
these
precious
waters
are
rich
with
surprise.
All
life
on
land
is
ultimately
dependent
upon fresh water. The mysterious tepuis of Venezuela isolated mountain
plateaus rising high above the jungle. This was the inspiration for Arthur
Conan Doyle's 'Lost World,' an imagined prehistoric land. Here, strange
towers of sandstone have been sculptured over the millennia by battering
wind and torrential rain. Moisture rising as water vapour from the surface
of the sea is blown inland by wind. On reaching mountains, the moisture
is forced upwards and as it cools, it condenses into cloud and finally rain
- the source of all fresh water. There is a tropical downpour here almost
every
day
of
the
year.
Fresh
water's
journey
starts
here,
high
in
the
mountains. Growing from humble streams to mighty rivers it will travel
hundreds
of
miles
to
the
sea.
Angel
Falls,
the
highest
waterfall
in
the
world. Its waters drop unbroken for almost a thousand metres. Such is the
height
of
these
falls
that
long
before
the
water
reaches
the
base
in
the
Devil's
Canyon
it's
blown
away
as
a
fine
mist.
In
their
upper
reaches,
mountain streams are full of energy. Streams join to form rivers, building
in power, creating rapids. The water here is cold. Low in nutrients, but

20

high in oxygen. The few creatures that live in the torrent have to hang on
for
dear
life.
Invertebrates
dominate
these
upper
reaches.
The
hellgrammite, its body flattened to reduce drag, has bushy gills to extract
oxygen from the current. Black fly larvae anchor themselves with the ring
of hooks, but if these become unstuck, they're still held by a silicon safety
line. There are advantages to life in the fast stream - bamboo shrimps can
just sit and sift out passing particles with their fan-like forearms. Usually,
these
mountain
streams
only
provide
enough
food
for
small
animals
to
survive. But with the spring melt here in Japan monsters stir in their dens.
Giant
salamanders,
world's
largest
amphibian,
almost
two
metres
long.
They're the only large predator in these icy waters. They begin their hunt
at
night.
These
salamanders
have
an
exceptionally
slow
metabolism.
Living up to 80 years they grow into giants. The fish they hunt are scarce
and salamanders have poor eyesight. But sensory nodes on their head and
body
detect
the
slightest
changes
in
water
pressure.
Free
from
competition, these giants can dine alone. Pickings are usually thin for the
salamanders, but every year some of the world's high rivers are crowded
by
millions
of
visitors.
The
salmon
have
arrived.
This
is
the
world's
largest fresh water fish migration. Across the northern hemisphere salmon,
returning from the ocean to their spawning grounds, battle their way for
hundreds
of
miles
upstream.
Up
here,
there
are
fewer
predators
to
eat
their eggs and fry. A grizzly bear. From famine to feast
- he's spoilt for

21

choice.
This
Canadian
bear
is
very
special
-
he's
learnt
to
dive
for
his
dinner. But catching salmon in deep water is not that easy and the cubs
have
lots
to
learn.
The
annual
arrival
of
spawning
salmon
brings
huge
quantities of food into these high rivers that normally struggle to support
much life. Although relatively lifeless, the power of the upland rivers to
shape the landscape is greater than any other stage in a river's life. Driven
by gravity, they're the
most erosive forces on the planet. For the past 5
million
years
Arizona's
Colorado
river
has
eaten
away
at
the
desert's
sandstone
to
create
a
gigantic
canyon.
It's
over
a
mile
deep
and
at
its
widest
it's
17
miles
across.
The
Grand
Canyon.
This
river
has
cut
the
world's
longest
canyon
system
-
a
1,000
mile
scar
clearly
visible
from
space.
As
rivers
leave
the
mountains
behind,
they
gradually
warm
and
begin
to
support
more
life.
Indian
rivers
are
home
to
the
world's
most
social
otter
-
smooth-coated
otters
form
family
groups
up
to
17
strong.
Group rubbing not only refreshes their coats, but strengthens social bonds.
When
it
comes
to
fishing
there
is
real
strength
in
numbers.
Fishing
practice begins when the cubs are four months old. Only the adults have
the speed and agility needed to make a catch. Adults share their catches
with their squabbling cubs. Most otters are solitary, but these rich warm
waters
can
support
large
family
groups
and
even
bigger
predators.
Mugger crocodiles, four metres long, could easily take a single otter. But,
confident in their gangs, the otters will actively harass these great reptiles.

22

Team play wins the day. The Mara river, snaking across the plains of East
Africa.
As
the
land
flattens
out
rivers
slow
down
and
lose
their
destructive
power.
Now
they
are
carrying
heavy
loads
of
sediment
that
stains their waters brown. Lines of wildebeest are on their march. Each
year
nearly
two
million
animals
migrate
across
the
Serengeti
plains
in
search of fresh green pastures. For these thirsty herds the rivers are not
only a vital source of drinking water, but also dangerous obstacles. This is
one of the largest concentrations of Nile crocodiles in Africa, giants that
grow
over
five
metres
long.
From
memory,
the
wildebeest
are
coming
and gather in anticipation. The crocodile's jaws snap tight like a steel trap
- once they have a hold, they never let go. It took over an hour to drown
this
full-grown
bull.
To
surprise
their
prey
crocodiles
must
strike
with
lightning speed. Here, only the narrowest line separates life from death.
Most rivers drain into the sea, but some end their journey in vast lakes.
Worldwide lakes hold twenty times more fresh water than all the rivers.
The East African Rift Valley holds three of the world's largest: Malawi,
Tanganyika, and Victoria. Lake Malawi, the smallest of the three, is still
bigger
than
Wales.
Its
tropical
waters teem
with
more
fish species
than
any
other
lake.
There
are
850
different
cichlids
alone,
all
of
which
evolved
from
just
one
single
ancestor
isolated
here
thousands
of
years
ago. These two-metre wide craters are fish-made. Fastidiously maintained
by
the
males,
these
bowls
are
courtship
arenas.
Cichlids
are
caring

23

parents.
Brooding
young
in
the
mouth
is
a
very
effective
way
of
protecting them. This lake can be a dangerous place. After dark, predatory
dolphin fish emerge from their daytime lairs among the rocks. Like packs
of sharks, they're on the prowl for sleeping cichlids. In the darkness these
electric fish hunt by detecting distortions in the electric field they create
around their bodies. Any cichlid that trenches out will be snapped up. The
floor of Lake Malawi drops 700 metres into an abyss. Here, in this dead
zone the larvae of lake fly midges hide out away from predators. In the
rainy
season
they
balloon
up
to
the
surface
and
undergo
a
magical
transformation. At dawn the first adult midges start to break out. Soon,
millions upon millions of newly hatched lake flies are taking to the wing.
Early
explorers
told
tales
of
lakes
that
smoked,
as
if
on
fire.
But
these
spiralling columns hundreds if metres high are mating flies. Once the flies
have mated, they will all drop to the water surface, release their eggs and
die. Malawi may look like an inland sea, but it's dwarfed by the world's
largest lake - Baikal in Eastern Siberia. 400 miles long and over a mile
deep, Baikal contains one fifth of all the fresh water found in our planet's
lakes and rivers. For five months of the year it's sealed by an ice sheet
over a metre thick. Baikal is the oldest lake in the world and, despite the
harsh conditions, life flourishes here in isolation. 80 percent of its species
are found nowhere else on Earth, including the world's only fresh water
seal.
With this
seal
and
its
marine-like
forests of sponges
Baikal
seems

24

more like an ocean than a lake. There are shrimp-like crustaceans - giant
amphipods - as large as mice. They are the key scavengers in this lake.
The water here is just too cold for the bacteria that normally decompose
the dead. Most rivers do not end in lakes but continue their journey to the
sea.
The
planet's
indisputable
super- river
is
the
Amazon.
It
carries
as
much
water
as
the
next
top-ten
biggest
rivers
combined.
Rising
in
the
Peruvian Andes, its main trunk flows eastwards across Brazil. On its way
the system drains a third of South America. Eventually, over 4,000 miles
from
its
source,
it
empties
into
the
Atlantic
Ocean.
The
Amazon
transports a billion tonnes of sediment a year, sediment clearly visible at
the
mixing
of
the
waters
where
one
massive
tributary,
the
Rio
Negro,
flows
into
the
main
river.
Its
waters
are
wonderfully
rich.
To
date
over
3,000 species of their fish have been described - more than in the whole
of the Atlantic Ocean. The Amazon is so large and rich in fish that it can
support
fresh
water
dolphins.
These
botos
are
huge
-
two
and
a
half
metres
long.
In
these
murky
waters
they
rely
on
sonar
to
navigate
and
hunt. They work together to drive shoals of fish into the shallows. Botos
are highly social and in the breeding season there is stiff competition for
mates. The males hold court in a unique way. They pick up rocks in their
jaws
and
flaunt
them
to
their
attending
females.
Maybe
each
male
is
trying to show how strong and dexterous he is and that he therefore is the
best father a female could have for her young. Successful displays lead to

25

mating. Even for giant rivers like the Amazon the journey to the sea is not
always smooth or uninterrupted. Iguassu Falls on the border of Brazil and
Argentina
is
one
of
the
widest
waterfalls
in
the
world
-
one
and
a
half
miles across. In flood 30 million litres of water spill over every second.
All the world's great broad waterfalls: Victoria, Niagara and here, Iguassu,
are
only
found
in
the
lower
courses of
their
rivers.
In their
final
stages
rivers broaden and flow wearily across their flat flood plains. Each wet
season here, in Brazil, the Parana river overflows its banks and floods an
area the size of England. The Pantanal
- the world's largest wetland. In
these slow-flowing waters aquatic plants flourish like the Victoria giant
water
lily
with
leaves
two
metres
across.
These
underwater
forests
are
nursery
grounds
for
fish.
Over
300
species
breed
here,
including
red-bellied
piranha
and
other
predators,
like
the
spectacle
caiman.
Ripening
fig
trees
overhanging
the
water's
edge
provide
welcome
food
for shoals of hungry fish. The commotion attracts dorado, known locally
as the river tiger. They patrol the feeding shoals, looking for a chance to
strike. And waiting in the wings, ready to pick off any injured fish, are the
piranhas. The feeding frenzy quickly develops. Piranha can strip a fish to
the bone in minutes. Great numbers of fish sustain vast flocks of water
birds. The rose-eared spoonbill is just one of the 650 bird species found in
the
Pantanal.
They
nest
alongside
wood
stocks
in
colonies
thousands
strong. Spectacle caiman linger below, waiting for a meal to fall out of

26

the sky. When rivers finally reach the sea they slow
down, release their
sediment
and
build
deltas.
In
Bangladesh
the
Ganges
and
Brahmaputra
rivers
join
to
form
the
world's
biggest.
Every
year
almost
2
thousand
million tonnes of sediment eroded from the Himalayas is delivered to the
ocean. At the delta's mouth - the largest mangrove forest in the world, the
Sundarbans. These extraordinary forests spring up throughout the tropics
in these tidal zones where rivers meet the sea. Crab- eating macaques are
mangrove
specials.
In
Indonesia
these
monkeys
have
adopted
a
unique
amphibious lifestyle
- they fish out fallen food. The troop also uses the
waters to cool off during the heat of the day. But the channels are also the
playground for restless young macaques. Some of the young have even
taken
to
underwater
swimming.
They
can
stay
down
for
more
than
30
seconds
and
appear
to
do
this
just
for
fun.
Yet
these
swimming
skills
acquired during play will certainly be useful later in life in these flooded
mangrove
forests.
In
cooler
climes,
mud,
laid
down
in
estuaries,
is
colonised
by
salt
marsh
grasses
and
form
one
of
the
most
productive
habitats on the planet. 400,000 greater snow geese flock to the estuaries
along
the
Atlantic
coast
of
the
United
States
to
rest
and
refuel
on
their
long
migratory
journeys.
This
is
the
end
of
the
river's
journey.
Collectively they've
worn down mountains and carried them
to the sea.
And all along the way, their fresh water has brought life and abundance to
planet Earth.

27


第
4
集

PLANET EARTH Caves




This
is
our
planet's
final
frontier,
an
inner
world
where
only
the
most
adventurous
dare
to
go.
Beneath
our
feet
are
countless
miles
of
cave
shafts and passages. The Cave of Swallows in Mexico, 400 metres to the
bottom,
deep
enough
to
engulf
the
Empire
State
Building.
This
is
the
biggest cave shaft in the world. Yet these depths were first explored only
two years before man landed on the moon. Today caves remain the least
explored places on Earth. However, human beings are seldom the first to
reach
these
black,
damp
places.
Here,
live
some
of
the
strangest
and
least-known animals on the planet. This galaxy of little lights is created
by thousands of living creatures. Any animal that lives in a cave has to
cope with complete blackness, but in New Zealand some have turned this
darkness to their advantage. A silicon strand is lowered from the ceiling,
alongside
hundreds
of
others.
Beautiful
though
these
threads
are,
they
have a sinister purpose. This is a cave glow worm. To trap its prey it goes
fishing with a line of silk. The silk comes from glands in the glow worm's
mouth and is loaded with droplets of mucus. Each glow worm produces
dozens of these threads. Once its lines are set, the glow worm hangs from

28

a
mucus hammock
and
waits, like
a patient angler. But the
glow
worm
doesn't leave everything to chance. That ghostly blue light is the result of
a chemical reaction taking place inside a special capsule in its tail. The
light
literally
shines
out
of
its
backside.
It's
a
lure
for
attracting
prey.
Insects seem irresistibly drawn towards the source and then get trapped
by the sticky lines. Once stuck, there is no escape. Now it's just a matter
of
reeling
in
the
line
and
slowly
consuming
the
catch
-
alive.
By
ensnaring
the
insects
that
hatch
in
this
cave,
these
glow
worms
have
solved the biggest challenge that permanent cave dwellers face - finding a
regular and reliable source of food. One kind of rock makes this whole
underground
world
possible
-
limestone.
Most
of
the
world's
caves
are
found
within
it
and
it
covers
nearly
10
percent
of
the
earth's
surface.
Limestone is composed of minerals derived from marine shells and corals,
so although this rocky escarpment in the United States is now hundreds of
metres above sea level it was actually formed under water. The limestone
towers of Vietnam's Ha Long Bay are a reminder of this link with the sea.
Originally, this whole area would have been one solid block of limestone,
the base of a coral reef. In Borneo, rain has sculptured the limestone into
extremely
sharp-sided
pinnacles.
But
the
dissolving
power
of
rainwater
has other, much more dramatic effects underground. Rivers that flow over
limestone
often
seem
to
completely
disappear.
When
the
water
reaches
the
more
resistant
bed
of
limestone
its
course
is
altered.
Once

29

underground, the water takes on a new,
more erosive power. During its
journey from the surface the water absorbed carbon dioxide from the soil
making it mildly acidic. And over millions of years this acid eats away
the limestone creating a maze of caverns and passages that sometimes go
on for miles. This is the biggest underground river passage in the world,
so big
a
jumbo
jet
could
fly
through
it.
It's
Deer
Cave, in
Borneo.
The
sheer
size
of
Deer
Cave
allows
some
animals
to
gather
there
in
huge
numbers. A staggering 3 million wrinkle-lipped bats live here. The bats
roost high on the walls and ceilings where they're well protected from the
outside elements and safe from predators. And while they're up here the
bats produce something very important. This hundred metre high mound
is made entirely of bat droppings - guano. Its surface is covered by a thick
carpet of cockroaches, hundreds of thousands of them. Caves are one of
the few habitats on Earth not directly powered by sunlight. In the absence
of plants this food chain is based on a continuous supply of bat droppings.
The
cockroaches
feed
on
the
guano
and
anything
that
falls
into
it.
The
droppings
also
support
other
types
of
cockroaches
which
spend
part
of
their day resting on cave walls. These in turn become food for giant cave
centipedes,
some
more
than
20
centimetres
long.
Bizarrely,
there
are
crabs
here,
too,
sifting
through
the
droppings
for
nutrients.
All
these
animals spend their entire lives within the cave. They're totally dependant
on
the
digested
remains
of
food
that's
brought
here
from
outside.
Each

30

evening in just two hours three million bats leave the safety of the cave to
hunt for insects in the forest outside. But not all will return. As they leave
the cave the stream of bats form a doughnut-shaped ring. The wheeling
bats seem to confuse a rufus-bellied eagle, but they must still survive the
attacks of other, more specialised, birds of prey. Peregrine falcons and bat
hawks are the jetfighters of the bird world. Good hunting will end as the
light fades so the bat hawks bolt their catches on the wing and fly straight
back
for
more.
Any
bat
separated
from
the
group
becomes
a
clear
and
obvious
target
and
is
asking
for
trouble.
Yet
the
nightly
onslaught
has
little impact on bat numbers
- by the morning the vast majority
will be
back in the safety of the cave. Bats are not the only commuters in these
Bornean caves. There's a day shift as well. Returning from hunting in the
sunlight
these
commuters
rely
on
their
loud
clicks
to
find
their
way
through the cave passages in total darkness. They're cave swiftlets. Like
bats they use echolocation to navigate. We need lights to see what's going
on, but in the pitch black the swiftlets manage unerringly to locate their
individual
nesting
sites,
which
are
only
a
few
centimetres
across.
It's
a
remarkable skill and one we still do not fully understand. These birds are
unusual
for
another
reason.
Their
little
cup-like
nests
are
made
entirely
from threads of saliva. It takes more than 30 days to complete one. The
nests are very precious objects, and not only for the birds. For 500 years
people have been harvesting the nests of cave swiftlets. It's a very risky

31

business. with virtually no safety equipment and using ladders made from
forest vines the gatherers climb into the highest reaches of the cave often
more than 60 metres from the floor. The work may be hazardous in the
extreme, but the rewards are great. The pure white nests of cave swiftlets
are the main ingredient of birds' nest soup and gram for gram are worth as
much
as
silver.
As
soon
as
its
nest
is
removed
a
bird
will
immediately
build another. So, as long as this valuable harvest is properly controlled,
the colonies will continue to flourish. These Bornean caves are among the
biggest in the world and they're still getting bigger as each year rainwater
eats away a little more limestone. But water in caves doesn't only erode.
It also builds. This water is loaded with dissolved limestone and when it
meets the air in the cave some of that is deposited as a mineral - calcite.
As it builds up so the calcite forms decorations that hang from the ceiling
- stalactites. Each drop leaves behind only a miniscule amount of calcite,
but
over
time
the
process
can
produce
some
spectacular
results.
If
the
water seeps though the ceiling quickly, then the calcite is deposited on the
floor of the cave and that creates stalagmites. Variations in water flow and
the air currents produce an infinite variety of forms, but all are created by
the same process - the slow deposition of dissolved limestone. And when
stalactite meets stalagmite a column is born. Structures like these in North
America's Carlsbad Cavern can take many thousands of years to develop.
But
sometimes
the formations
in
a cave stop
growing
altogether.
These

32

flooded
caves
in
Mexico
have
remained
virtually
unchanged
for
thousands of years. Since the last Ice Age they've become cut off from the
outside world. Yet their impact on life on the surface has been huge. 500
years ago they supported one of the world's great civilisations the Maya.
Mexico's Y
ucatan Peninsula has no rivers, lakes or streams so the Maya
relied
on
the
cenotes
-
the
flooded
entrances
to
the
water-filled
caves.
These flooded shafts are the region's only source of open fresh water. The
cenotes
are,
in
effect,
gigantic
fresh
water
wells.
Away
from
the
life-giving rays of sunshine one might not expect to find plants. But in the
darkness of the cave tunnels roots of giant tropical trees have pushed their
way
through
cracks
in
the
limestone
to
reach
the
flooded
caverns.
Without this water the Yucatan's forest could not grow so luxuriantly. The
Maya knew that their lives depended on this water, but it's only with the
help
of
today's
technology
that
we've
come
to
appreciate
the
full
significance
and
scale
of
these
flooded
passageways.
So
far,
more
than
350 miles of underwater galleries in the Yucatan have been mapped, but
still nobody
yet knows the true extend of this subterranean waterworld.
And
with
good
reason.
Underwater
caving
is
notoriously
dangerous.
When the nearest exit may be hundreds of metres or more away, running
out
of
air
down
here
would
be
fatal.
To
avoid
getting
lost
divers
carry
with them a spool of string. It becomes their lifeline - literally. The string
also doubles as a measuring tape - a technique that has been used here, in

33

Mexico, to chart the largest underwater cave in the world - all 100 miles
of it. Cave exploration often requires you to push yourself through narrow
gaps
in
the
rock.
Cavers
call
such
places
'squeezes.'
The
tighter
the
squeeze,
the
greater
the
chance
of
damaging
some
vital
life-support
system. In these conditions a diver could easily become disorientated and
that could be fatal. The flooded caverns can play tricks on you in other
ways. What seems like air, isn't. It's just another kind of water. This is a
halocline - a meeting of fresh and salt water. Fresh water from the jungle
flows
over
the
heavier
salt
water
from
the
sea.
The
saltwater
layer
is
extremely
low
in
oxygen
making
it
a
particularly
difficult
place
for
animals to live. Yet some have managed it, like the remiped, one of the
most
ancient
of
all
living
crustaceans.
The
Maya
understood
the
importance
of
the
cenotes,
but
they
could
never
have
known
that
these
flooded passageways were actually the beginning of subterranean rivers,
all of which eventually flow out to the sea. Salt water, unlike fresh water,
does
not
erode
limestone,
so
most
sea
caves
are
created
by
the
mechanical pounding of the waves. The rocky outcrops of New Zealand's
Poor
Knight
Islands
are
riddled
with
sea
caves
and
just
like
those
in
Borneo
they
have
become
important
shelters
for
many
species.
After
a
day feeding in the open water vast shoals of demoiselle fish return to the
caves, which they use as a refuge from predators. For these fish the caves
are a night time retreat, but they're not the only commuters in here. There

34

are
other
fish
working
to
a
different
schedule.
The
bigeyes
are
the
equivalent of bats. Night feeders leave the cave each evening. And like all
cave
commuters
they
are
most
vulnerable
at
the
scheduled
time
of
departure.
A
bottleneck
funnels
these
exiting
bats
into
dense
concentrations attracting the attention of others. The bats can detect the
snakes using echolocation, but the snakes are literally in the dark - they
can
see
nothing.
The
strikes
seem
to
be
largely
hit-and-miss,
but
the
snakes have a secret weapon. They can actually sense each bat flying past.
Receptors in the snake's head pick up the heat given off by the flying bats,
as
this
thermal
image
shows.
To
the
snakes
the
bats
are
apparently
glowing and this gives them something to aim at. This is the price that
these cave commuters must pay for their daytime sanctuary on the ground.
Small wonder then that there are other cave dwellers that stay put. Many
caves
are
like
islands
-
cut
off
from
the
outside
world
and
from
other
caves. This isolation has resulted in the evolution of some various strange
creatures. They are the cave specialists - troglodytes, animals that never
emerge from the caves or see daylight. These troglodytes from Thailand
are possibly the most specialised creatures on Earth for they live only in
cave waterfalls. The entire population of these cave angel fish seems to
be
restricted
to
just
two
small
caves.
It's
the
same
story
with
other
troglodytes.
There
may
well
be
less
than
a
hundred
Texas
cave
salamanders in the wild. And the Belizean white crab is another creature

35

that is unique to just one cave system. Living in perpetual darkness they
have all not only lost the pigment in their skin, but also their eyes. It takes
thousands of generations for eyes to be lost, so these species must have
been
isolated
for
a
very
long
time.
But
the
blind
salamander
has
other
highly
developed
sensory
organs.
Receptors
in
their
skin
detect
minute
movements in the water made by its prey. External gills help it to breathe
in water that is particularly low in oxygen. The cave angel fish feed on
bacteria
in
the
fast
flowing
water
keeping
their
grip
with
microscopic
hooks on their fins. Food is often in short supply and troglodytes like the
crab have to survive on whatever washes into the cave from outside. The
salamander
might
not
encounter
food
for
several
months,
so
when
something does come along it can't afford to miss it. It's astonishing that
these extraordinary cave dwellers manage to survive at all. But one cave
is
so
inhospitable
that
one
would
not
expect
it
to
contain
any
life
whatsoever.
The
water
flowing
out
of
the
Villa
Luz
cave
in
Mexico
is
actually
coloured
white
with
sulphuric
acid.
Explorers
entering
this
dangerous
cave
must
wear
respirators
and
carry
monitors.
Poisonous
gases
rise
to
fatal
levels
so
quickly
that
an
early
warning
system
is
essential.
Bats
survive
by
staying
close
to
the
skylights,
but
venturing
deep
into
the
cave
is
very
dangerous
indeed.
The
source
of
these
toxic
fumes lies several miles below. Hydrogen sulphide gas bubbles up from
oil deposits in the earth's crust. It mixes with oxygen and the water, and

36

forms sulphuric acid. These are not the sort of conditions in which you
would expect to find fish, yet these cave mollies seem to thrive despite
the
acid
and
the
low
levels
of
oxygen.
There
is,
in
fact,
more
life
here
than anyone would think possible, but the biggest surprise is something
altogether
more
bizarre.
These
strange
stalactite-like
formations
are
known, rather appropriately, as snotites, the drops dripping from the ends
are sulphuric acid, strong enough to burn skin. The snotites are, in fact,
vast
colonies
of
bacteria,
capable
of
going
a
centimetre
a
day.
In
this
world
without
sunlight
these
bacteria
extract
energy
from
the
hydrogen
sulphide
gas.
Bacteria
like
these
are
known
as
extremofile
because
of
their ability to survive in such extreme conditions. And these extremofiles
play another important role in this cave. Surprisingly, they are the basis of
a food chain which supports, amongst other creatures, the larvae of these
midges.
Villa
Luz's
ecosystem
was
certainly
very
remarkable,
but
cave
explorers
were
soon
to
make
an
even
more
astonishing
discovery.
Beneath
this
arid
landscape
lies
a
subterranean
wonderland.
Without
water one might not expect to find any caves, but beneath these rolling
desert slopes in the United States lies one of the longest, deepest and most
surprising caves in the world. Its secrets remained unknown until 1986,
when cavers dug through several metres of loose rock to the bottom of
this pit. They named the cave 'Lechuguilla' and since this discovery more
than
120
miles
of
passageways
have
been
mapped.
When
the
first

37

explorers
descended,
no-one
guessed
at
the
sheer size
of this
cave.
But
even that was not going to be the biggest surprise. Little did they realise
that Lechuguilla would soon be regarded by cavers the world over as the
most beautiful of all caves. They were about to discover some of the most
exquisite formations ever seen underground. The walls were covered with
the most delicate and fragile crystals. Many of these crystals were made
of
gypsum,
a
mineral
that
comes
from
limestone.
And
there
was
mile
after mile of them. Water is the creator of most caves, but, unlike all other
limestone caves, Lechuguilla's rock had not been eaten away by running
rainwater.
Something
else
was
responsible.
The
only
water
Lechuguilla
has are these wonderfully still clear pools. As the explorers went deeper
into
the
cave,
they
came
across
whole
galleries
filled
with
the
most
unusual
formations,
like
these
5-metre
cones,
frosted
with
the
most
delicate
crystals.
It
was
Lechuguilla's
gypsum
crystals
that
made
scientists question how these caverns were formed. They discovered that
Lechuguilla's limestone had actually been eaten away by sulphuric acid,
cutting
through
literally
miles
of
limestone.
And
when
sulphuric
acid
dissolves
limestone
it
leaves
behind
gypsum,
the
basis
of
Lechuguilla's
remarkable formations. And there was one set, more than a mile from the
surface,
that
almost
defied
belief.
The
Chandelier
Ballroom
was
the
ultimate
discovery.
With
its
six-metre
long
crystals
it's
surely
the
most
bizarre cave chamber in the world. And the walls had one further surprise.

38

Extremofile
bacteria
were
found
to
be
feeding
on
the
rock
itself.
The
discovery of life that exists without drawing any of its energy from the
sun
shows
us
once
again
how
complex
and
surprising
the
underground
world can be. Each year explorers chart over a hundred miles of new cave
passages.
But
with
half
the
world's
limestone
still
to
be
explored,
who
knows how many Lechuguillas are still waiting to be discovered?

第
5
集

PLANET EARTH Deserts




A third of the land on our planet is desert. These great scars on the face of
the Earth appear to be lifeless, but surprisingly none are. In all of them
life manages somehow to keep a precarious hold. Not all deserts are hot.
Fifty-mile-an-hour winds blowing in from Siberia bring snow to the Gobi
Desert
in
Mongolia.
From
a
summer
high
of
50
degrees
centigrade
the
temperature in midwinter can drop to minus 40, making this one of the
harshest deserts of all. Few animals can survive these extreme changes.
Wild
Bactrian
camels,
one
of
the
rarest
mammals
on
the
planet.
And
perhaps
the
hardiest.
Their
biggest
problem
is
the
lack
of
water,
particularly
now,
in
winter,
when
the
little
there
is
is
locked
up
as
ice.
Surprisingly, snow here never melts. The air is just too cold and too dry

39

for it to do so. The sun's rays turn it straight into vapour. It evaporates.
But it is the only source of water, so Bactrian camels eat it. Elsewhere in
the world a camel at a waterhole can drink as much as 200 litres during a
single visit. Here the strategy is to take little and often. And with good
reason, for filling the stomach with snow could be fatal. The camels must
limit
themselves
to
the
equivalent
of
just
10
litres
a
day.
Winter
is
the
time
for
breeding.
This
extraordinary
performance
is
a
male
Bactrian
camel's way of attracting the attention of a passing female. In summer the
camels can't stray far from waterholes. But now, with mouthfuls of snow
lying everywhere they can travel widely in search of mates. Today less
than a thousand of these desert specialists remain in the wild. The Gobi,
hostile though it is, is their last stronghold. There's no other desert quite
like
the
Gobi,
but
why
is
this
place
a
desert?
There
is
one
simple
and
massive
cause
-
the Himalayas.
Clouds
blowing
from
the
south
hit
this
gigantic barrier. As they're forced upwards so they empty their moisture
on the mountain slopes, leaving little for the land on the other side. From
the space deserts are very conspicuous. Dunes of sand hundreds of miles
long
streak
their
surface.
With
no
cloak
of
vegetation
to
conceal
them
strange formations are exposed in the naked rock. Africa's Sahara is the
largest
desert
of
all.
It's
the
size
of
the
United
States
and
the
biggest
source of sand and dust in the entire world. Sandstorms like these appear
without
warning
and
reduce
visibility
for
days
over
areas
the
size
of

40

Britain.
Dromedaries,
single-humped
camels,
take
these
storms
in
their
stride. The heaviest sand rises only a few metres above the ground, but
the dust can be blown 5,000 metres up into the sky. The ferocious wind,
armed
with grains
of
sand, is
the agent that
shapes
all deserts.
Reptiles
have armoured scaly skins that protect them from the stinging grains. For
insects the bombardment can be very severe indeed. The only escape is
below the surface. As the winds rise and fall, swallow and eddy so they
pile
the
sand
into
dunes.
These
sand
scenes
can
be
hundreds
of
miles
across. In Namibia the winds have built some of the biggest dunes in the
world. Star dunes like these can be 300 metres high. Grains, swept up the
flanks, are blown off the crests of the ridges so it's only the tops that are
moving.
The
main
body
of
these dunes may
not
have
shifted
for
5,000
years. Few rocks can resist the continuous blast of the sand carrying wind.
These outcrops are standing in Egypt's White Desert. But they will not do
so
for
much longer. They're
being inexorably
chiseled away
and
turned
into more sand. Now lumps of heavily eroded rocks have been marooned
in a sea of sand. These jagged pyramids a hundred metres tall were once
part
of
a
continuous
rocky
plateau.
The
blasting
sand
will
eventually
eliminate them altogether. The relentless power of the wind ensures that
the
face
of
a
desert
is
continually
changing.
But
there
is
one
constant
presence - the desert sun. The sun's heat and power to evaporate water has
had
a
profound
effect
on
the
bodies
and
habits
of
everything
that
lives

41

here.
This
sun
potentially
is
a
killer.
And
the
red
kangaroos
must
acknowledge that. Right now, while the sun is low, there's no immediate
cause
for
concern.
But
this
situation
won't
last
long.
Australia
is
the
world's most arid continent with blistering daytime temperatures. Every
hour the temperature rises by five degrees centigrade. Soon the heat will
reach a critical point. Any kangaroo out in the open is in serious danger of
overheating.
In
the
full
sun
the
temperature
on
the
ground
soars
to
70
degrees. By midday the radiation is so intense they must take shelter. In
the shade they're shielded from much of the sun's energy but their body
temperature can still rise. So they lick saliva on to their forearms where
there is a network of blood vessels close to the surface of the skin and, as
the
saliva
evaporates,
their
blood
is
cooled.
This
thermal
image
shows
just
how
effective
the
process
is.
The
blue
areas
on
the
body
are
the
cooler
parts.
As
the
saliva
dries
it
has
to
be
replaced
and
this
is
a
real
drain on the kangaroo's body fluids. Even in the shade the earth is baking
hot
so
the
kangaroos
dig
away
the
warmed
topsoil
to
get
at
the
cooler
ground beneath. By staying in the shade and licking to control their body
temperature kangaroos manage to get through the hottest part of the day
without heat stroke. But for the majority
of desert animals this strategy
would not be enough for survival. The extraordinary ears of the fennec
foxes of Africa radiate heat but the animals have another way of keeping
cool.
They
spend
their
days
underground
and
only
emerge
at
sunset.

42

Darkness brings huge changes. In the Sahara the temperature can drop as
much as 30 degrees during the night, so it's cool enough to allow these
desert fox cubs to play. All sorts of creatures now appear including some
really unexpected ones. Toads have permeable skins and would quickly
die from desiccation out in the daytime heat. It's only now that they can
leave shelter. The same is true for scorpions, even though their shells are
actually watertight. In fact, most small desert creatures are nocturnal. so
it's only now that you can judge just how much life there can be in the
desert.
But
moisture,
lost
even
at
night,
has
to
be
replaced
sometime
somehow and that problem dominates the lives of all desert dwellers. The
Atacama in Chile. This is the driest desert in the world. Some parts may
not see rain for fifty years and with such a record you'd expect the place
to
be
completely
barren.
These
are
South
America's
camels,
guanacos.
They're
very
good
at
conserving
moisture
but
they
nonetheless
need
a
regular
supply
of
water.
They
get
it
partly
from
cactus
flowers
but that
explanation
raises
another
question.
How
do
the
cacti
survive
without
rain?
Hot
winds
suck
all
the
moisture
from
the
surface
of
the
land.
Clearly
there
must
be
something
else
that
takes
the
place
of
rain.
The
secret is a cold sea current that runs parallel to the land. The cold water
cools the moist warm air above it and that produces banks of fog. At the
same time wind blowing on to the shore sweeps the fog inland. Before
long the cacti are dripping with dew. The fog is so regular that moisture

43

loving lichens are able to grow on the cacti and they absorb liquid like a
sponge. In the land of almost no rain these precious drops are life-savers
for many different creatures. Further inland the air remains so warm that
its moisture does not condense so this slender strip of desert is virtually
the only part of the Atacama where life can exist. Without the fog, this
land, too, would be empty. The guanacos make the most of the dew but it
will not remain for long. In an hour or two the sun will have burnt it off
and
dry
the
surface
of
the
cacti.
The
Sonoran
desert
in
Arizona
is
not
quite so dry as the Atacama - some rain does fall. But it is infrequent and
when it does arrive animals and plants have to be ready to make the most
of
it.
And
it's
coming.
When
the
summer
monsoon
blows
in
the
giant
saguaros, one of the biggest of all cacti, are ready to take full advantage
of it. After a rainstorm the saguaro's long shallow root system sucks up
the water and the pleats on its trunk enable it to expand rapidly. When full,
a saguaro stem can store up to five tonnes of water and that's enough to
see it through many months of drought. The trunks of these huge plants
provide
homes
for
the
gila
woodpecker.
But
birds
are
not
the
only
animals to benefit from the presence of the cacti. During four weeks of
the summer the saguaros bloom at night to attract visitors. The pollen and
nectar
with
which
these
flowers
are
loaded
attract
long-nosed
and
long-tongued bats. The bats left Mexico a few days earlier to escape the
heat of summer and are on their way north to the southern United States.

44

To get there, they have to cross the Sonoran desert. But the desert is so
big that for most of the year they would be unable to cross it. Now, with
the saguaro in bloom, they can refuel on the way. So the saguaro's success
in developing a way to store water is now crucial to most of the animals
that live or even travel through this land. The scarcity of rain determined
the shape of this icon of the desert but water, scarce thought it is, has also,
like the wind, shaped the land itself. In the deserts of Utah ancient rivers
flowing across sandstone country steadily widen their canyons until now
the
land
between
them
has
been
reduced
to
spires
and
pinnacles.
With
little or no soil to retain the water on the surface of the land life here is
scarce indeed. And when resources are limited, conflict is never far away.
These
are
Nubian
ibex
and
they
are
squaring
up
for
a
duel.
And
when
trouble
starts,
a
smart
ibex
knows
that
the
best
thing
to
do
is
to
gain
higher ground. These are actually subordinate male ibex, but their fights
are nonetheless serious. Losing one might mean never getting the chance
to
breed
ever.
When
competitors
are
evenly
matched
as
they
are
here,
duels can last for an hour. In this heat the effort is trully exhausting. But
victory here will gain important ranking points on a male's way to the top.
There's so much at stake that not all play fair. The battle has produced the
winner, but the ultimate prize is not his yet. That currently belongs to the
dominant male ibex. His rank earns him the loyalty of a harem of females
and they follow him closely as he travels across this desert searching for

45

foof and water. He doesn't have to waste time looking for mates - they're
his
for
the
taking,
so
he
can
concentrate
with
them
on
keeping
fit
and
healthy.
Lizards
are
desert
specialists.
But
here,
their
numbers
are
extraordinary. These crevices in South Africa contain the highest density
of lizards in the world. They're called flat lizards for obvious reasons, and
they flaunt their multi-coloured bellies in territorial disputes. He's made
his point, and now it's time to find some food. As the day warms up, the
lizards move away from their cracks and head down to the bottom of the
gorge. Their goal is the river. There is no food at the edge, but this desert
river holds a secret. Each day blackfly rise from turbulent stretches of the
river. This is what the lizards have come for. The black fly never land, so
the lizards have to leap for their food. In one day each of these acrobatic
little lizards may catch 50 flies. There are plenty of flies to go round, even
with hundreds of lizards competing for them. Away from these rapids flat
lizard
populations
are
found
in
much
smaller
numbers.
But
here
one
unusual abundance has produced another. Deserts are created by the lack
of water, but what actually kills animals here is not heat or thirst, but lack
of food. So how on earth does a plant-eater this size survive in a place
apparently
totally
devoid
of
vegetation?
Elephants
in
Namibia
are
the
toughest
in
Africa.
And
they
need
to
be.
What
little
food
exists
is
so
dispersed that these elephants walk up to 50 miles a day as they travel up
the dry river channels searching for something to eat. At times the task

46

looks truly helpless. Elephants may seem out of place in this landscape,
but they're not the only ones. Amazingly, lions live here, too. In savanah
country huge herds of games support prides containing 20 lions or more.
But to live here lions have had to change their habits
- prides are much
smaller and their home ranges are very much bigger. And there's an added
problem - their food is always on the move. Like the elephants, the lions
must travel great distances to find enough to live on. But lions can't go
everywhere - they won't attempt to cross this field of sand dunes and the
oryx know it. The lions must wait for the oryx to leave the safety of the
dunes, which eventually they must to find food and water. And then the
lions will ambush them. The elephants have found some of their favourite
food.
Grasses
are
the
staple
diet
of
all
elephants,
but
this
herd
concentrates
on
digging
up
the
roots,
which
have
more
nutrition
and
moisture than the stems. It's the sort of behaviour that can make all the
difference
in
a place
of serious shortages.
Yet
all this
can
change
in an
instant.
The
fortunes
of
many
deserts
are
ruled
by
distant
rains.
This
water
fell
as
rain
in
mountains
more
than
a
hundred
miles
away.
It's
known as a flash flood and called that because the water may run for just
a single day. It's an event that only happens once or twice a year at the
most. The sandy riverbed acts like a giant strip of blotting paper sucking
up
the
water
as
soon
as
it
appears.
But
every
square
metre
of
soil
moistened by this river will increase the chances of survival for those that

47

live here. Waterholes are filled temporarily. Elsewhere in Africa elephants
drink
every
day,
but the lack
of
water here
means
that
desert elephants
can only refill their tanks once every four or five days. Within a week the
flash flood has produced a flush of green, more than enough to draw the
oryx out of the dunes. It's a rare chance for them to build up their food
reserves.
The
flood has
made
life
easier for the lions, too.
The
flesh of
this
oryx
will
keep
the
family
going
for
a
week
at
the
most.
But
for
a
while the hunting will be easier, now that river channel has turned green.
The
good
times
for
lions
and
oryx
are
brief,
but
these
are
the
short
moments
that
make
it
possible
to
live
in
deserts
the
year
round.
Death
Valley
is
the
hottest
place
on
Earth.
Yet
even
this
furnace
can
be
transformed
by
water.
A
single
shower
can
enable
seeds
that
have
lain
dormant for 30 years or more to burst into life. And there hasn't been a
bloom like this one for a century. The periods of boom in Death Valley
are
short.
but
they're
just
frequent
enough
to
keep
life
ticking
over.
A
sudden
flush
of
vegetation
is
what
every
desert
dweller
waits
for,
and
when it happens they must make the most of it. There is no other species
on
the
planet
that
responds
as
quickly
and
as
dramatically
to
the
good
times as the desert locust. Eggs that have remained in the ground for 20
years begin to hatch. The young locusts are known as hoppers, for at this
stage they're flightless. They find new feeding grounds by following the
smell
of
sprouting
grass.
Normally
it
takes
four
weeks
for
hoppers
to

48

become
adults,
but
when
the
conditions
are
right
as
now
their
development
switches
to
the
fast
track.
As
the
vegetation
in
one
place
begins to run out the winged adults release pheromones - scent messages,
which tell others in the group that they must move on. And when groups
merge,
they
form
a
swarm.
An
adult
locust
eats
its
entire
body
weight
every day, and a whole swarm can consume literally hundreds of tonnes
of vegetation. They have to keep on moving. The swarm travels with the
wind - it's the most energy-saving way of flying. Following the flow of
wind
means
that
they're
always
heading
toward
areas
of
low
pressure,
places where wind meets rain and vegetation starts to grow. As they fly,
swarms
join
up
with
other
swarms
to
form
gigant???ic
plagues
several
billions strong and as much as 40 miles wide. They will consume every
edible thing that lies in their path. This is one of planet Earth's greatest
spectacles. It's rarely seen on this scale and it won't last long. Once the
food is gone, the steady roar of a billion beating locust wings will once
again be replaced by nothing more than the sound of the desert wind.

第
6
集

PLANET EARTH Ice Worlds




Both
poles
of
our
planet
are
covered
with
ice.
They're
the
largest
and

49

most demanding wildernesses of all. Nowhere else on Earth is seasonal
change so extreme. It causes the ice to advance and retreat every year and
all
life
here
is
governed
by
that.
When
the
first
polar
explorers
headed
south giant cathedrals of ice marked their entry into uncharted territory.
Passing the towering spires they must've wondered what unearthly sights
lay in store. As they battled on the ice became increasingly dominant but
nothing could have prepared them for the ice world that finally loomed
into
view.
Terra
incognita
-
the
unknown
land.
At
the
southernmost
extreme of our planet the continent of Antarctica is as large as the United
States of America. Ninety percent of all the world's ice is found here. This
frozen world is largely deserted until the start of spring. Adelie penguins
in a hurry. The clock is ticking. Instead of waiting for the summer melt
the new arrivals hasten south over the frozen sea. They have come here to
breed but polar summers are so short they must be in position before the
thaw starts. As the sea ice retreats life can journey farther south. Antarctic
waters are so rich that visitors come from far and wide to harvest them.
Vast numbers of chinstrap penguins come ashore to breed. No bird will
lay their eggs directly onto ice so bare rock is a vital commodity. The best
patches are worth the climb. The clifftops are soon stained pink with the
droppings of tens of thousands of nesting penguins. Only in a land almost
entirely covered in ice could bare rock be reckoned an oasis. Some will
travel into the heart of the continent to find it. These are noon attacks the

50