生命（2009）

《哺乳动物》
南极洲
Antarctica.
全球最冷
The earth's coldest continent,
最不适合生物居住的大♥陆♥
the one that is most hostile to life.
在这个离南极 一千三百公里的地方
Here, 800 miles from the South Pole,
气温是零下四十度
it's 40 degrees below zero.
全世界有几百万种动物
Of all the millions of species of animals on Earth,
只有一种可以在这里永久居留
only one can live here permanently.
这是一只威德尔海豹
A Weddell seal.
它可以潜到冰层下方 所以可以在这里生存
She can survive because she can dive below the ice.
海豹在冰层下面 可以躲避上方的风暴
Here she is protected from the storms above,
也可以在这里觅食
and here too, she can find food.
但海豹是哺乳动物 要呼吸空气才能活
But she is a mammal, and she has to breathe air,
所以要有一条 可以直通上方冰雪世界的生命线
so she has to keep a lifeline open to the world above the ice.
这不只是它的生命线 也是它新生宝宝的命脉
Not only for her, but now for her newborn pup.
小海豹出生不到一个星期还很脆弱
He's less than a week old, and still very vulnerable.
一场暴雪夹着狂风席卷而来
A blizzard blows in, and with it, storm-force winds.
这种暴雪有时会持续一个星期
It could last for a week.
海豹是哺乳动物 所以会有体热
Being mammals, seals can generate heat within their bodies.
皮毛与厚厚的脂肪
And their fur, with a thick layer of fat beneath it,
可以防止大部分的体热散失
prevents most of that heat from escaping,
就算是天寒地冻也不怕
even in cold conditions like this.
而且母海豹可以用
What is more, she is able to feed her youngster
只有哺乳动物才会分泌的乳汁 喂养自己的宝宝
with that mammalian speciality, milk.
母海豹一边喂奶 一边为宝宝挡住狂风暴雪
And while she does so, she shields him from the worst of the blizzard.
母海豹整个冬天都努力防止
She has worked hard throughout the winter to prevent her breathing hole
冰层上的呼吸洞被冰雪堵死
in the ice from freezing over.
所以它得不断地用牙齿
That requires constant attention -
锉平呼吸洞的边缘
filing back the edges of the hole with her teeth.
小海豹一学会游泳 就要和母亲一块潜到冰层下方
Her pup needs to join her under the ice as soon as he can swim properly.
母海豹不断地哄宝宝下水
She encourages him to take his first plunge, but,
但可想而知宝宝并不想下去
hardly surprisingly, he is not keen.
小海豹必须在母亲的引导下 学习在水中猎食
Now, guided by his mother, he has to learn how to hunt underwater,
及在这座海底迷宫里
and to find his way back
找到回呼吸洞的路线
through the maze to his hole in the ice.
温暖的身躯，皮毛，乳汁 和母亲的呵护
A warm body, fur, milk and maternal care
是威德尔海豹在这片冰天雪地
are essential
生存的关键
for the Weddell seal's survival in this freezing environment.
哺乳动物凭着这些特质
And those qualities have helped the mammals
进驻了世界的每一个角落
to colonise the entire globe.
赤道附近的东非地区
Equatorial East Africa.
这里和南极洲有天壤之别
It's hard to image a place more different from Antarctica.
哺乳动物要有特殊本领 才能在这里生存
To survive here, mammals need additional talents.
这棵树下是一只 娇小哺乳动物的地盘
This tree shelters the territory of a tiny mammal
它终其一生都过得狂乱忙碌
that spends its whole life in frenzied activity.
这种动物以前叫做象鼩鼱
It used to be called an elephant shrew,
但现在很多人都改用 它的非洲名字桑吉
but now it's called by its African name of sengi.
这是一只母红象鼩鼱
This is a female rufous sengi.
和所有的象鼩鼱一样，它因为活动量极大 所以时时刻刻都觉得饿
And, like all sengis, she's so active, she's permanently hungry.
为了填饱肚子
To get all the food she needs,
它除了勤劳之外还得要有创意
she has to be both industrious and ingenious.
它建立了一个 错综复杂的道路网络
She has made an intricate network of trails
以有效率地捕食昆虫
that enable her to hunt her insect prey very efficiently.
但这些道路的另一个重要功能
But these pathways have another important function
在它碰到敌人时就派上用场了
when she meets her enemies.
在脑中牢牢记住七横八竖的路线图 在紧要关头时
Having a map of these trails in her head can mean the difference
可以让它保住一命
between life..and death.
不同于爬虫类，哺乳动物的四肢 位于身体的正下方
Like most mammals, and unlike reptiles, her legs are directly beneath her body.
所以象鼩鼱的稳定度虽然稍嫌不足 但是速度和灵活度大大加分
That makes her less stable, but much faster and more agile.
这只红象鼩鼱不但跑赢了对手 也把它唬得一愣一愣
Not only has she outrun this reptile, she's outwitted him.
幸好是这样
And just as well,
因为它已经当妈妈了 有自己的孩子要照顾
for she is a mother and has a youngster to care for.
象鼩鼱的成功靠的是速度和机智
The sengi relies on speed and cunning for its success.
别种哺乳动物 有很不一样的生存技巧
Other mammals have very different techniques.
有一种怪异的哺乳动物
Here in Madagascar,
正悄悄地在马达加斯加移♥动♥
one of the most bizarre of all mammals is on the prowl.
指猴和象鼩鼱一样 也是靠吃昆虫过日子的
The aye-aye, like the sengi, lives on insects.
但指猴的食物
But the ones that she seeks, she can't see,
是躲在树枝内部的
for they're buried deep inside branches.
蛴螬
They're beetle grubs.
不过指猴自有办法找到它们
To find them, she has a special talent.
它用手指 以每秒八下的速度轻敲树枝
She taps her fingers on the wood up to eight times a second,
细心聆听共鸣的细微变化
and listens for the tiny change in resonance
找出树枝内部的空洞
that indicates a hollow spot within.
指猴的听觉非常灵敏 所以能精准锁定位置
Her hearing is so acute, she can identify the precise position
咬开树枝，找到里面的蛴螬
in which to gnaw a hole in order to reach the grub.
再用超长的中指把蛴螬捞出来
And she has a grotesquely long middle finger with which to skewer it.
小指猴要花四年 才能练成这种独门密技
It takes a young aye-aye four years to perfect this technique.
不过一旦出师，就可以抓到
But once it has done so,
别的哺乳动物鞭长莫及的猎物
it can collect prey that no other mammal can reach.
极地冻原
The Arctic tundra.
觅食难度也很高
Food is hard to find here too.
这块土地过于贫瘠 所以大动物多半无法在这里生存
Indeed, this land is so barren that few large animals can live here.
但是有一种哺乳动物 在这里安身立命
Yet one mammal has found a way to do so.
时值晚春
It's late spring,
日渐炎热的阳光温暖了大地
and as the mounting strength of the sun warms the land,
八百万头驯鹿展开了北行的旅程
eight million reindeer move north.
但是这里的植物少得可怜
But the vegetation is so meagre
驯鹿群得不断迁移
that the only way the herds can get enough
才能填饱肚子
is to keep constantly on the move.
新生的小驯鹿很快就发现 它们为了觅食
Newborn calves soon discover
得从早走到晚
that they will have to spend every day walking in search of food.
驯鹿的耐力惊人
They have extraordinary endurance.
有的驯鹿一辈子走的距离
Some of these animals, before they die,
可以绕地球三圈
will have trekked for a distance equivalent to three times around the earth.
现在是青草最丰美的时节
Grazing is now at its best.
但驯鹿最大的敌人 也在这时候出现
But this also the time when the reindeer' worst enemy appears...
会叮咬它们的苍蝇
Biting flies.
这些苍蝇不但烦人
The flies not only drive them to distraction,
而且一天的吸血量高达半公升
but they can drain a pint of blood each day.
但是驯鹿也有因应之道
But the reindeer have a defensive strategy.
它们不断地挤向 苍蝇比较少的鹿群中♥央♥
Each individual tries to push its way into the centre of a group where there are fewer flies.
大伙儿不停的你推我挤
With all this pushing and jostling,
母驯鹿得把宝宝紧紧带在身边
mothers need to keep their calves close.
有时驯鹿被苍蝇闹得忍♥无可忍♥
Sometimes the flies become so bad the reindeer can stand them no longer
拔腿冲到
and they bolt
苍蝇飞不上去的高处
to higher ground where the flies can't follow.
但逃亡的代价高昂
But the price of escape can be high.
一对驯鹿母子在忙乱中走散
In the rush, one mother has lost her calf.
但别人已经找到小驯鹿了
Others have already found it.
鹿群早已走远
The herd has long since moved on,
但它在强烈母性本能的驱使下
but her maternal instinct is so strong
独自留下来 花好几天寻找自己的宝宝
she'll stay to search for her missing calf for days.
驯鹿群暂时逃离了可恶的苍蝇
The reindeer are free from flies for now,
但是高地上没有食物
but with no food on these high slopes,
它们迟早要回到山下的草原
they will eventually be forced to descend to find new pastures
再度面对苍蝇大军
and face the biting swarms once more.
这些哺乳动物的迁徙距离之长 在动物王国里
No animal makes a longer migration across the lands of the earth
无人能出其右
than these mammals.
另一种得长途迁徙的哺乳动物
Other mammals have found a more economic way
找到了更经济，更快速的方法
of travelling huge distances and at greater speed.
它们用飞的
They go by air.
巨大的黄果蝠住在刚果的森林里
Giant straw-coloured fruit bats inhabit the great forests of the Congo.
它们的翼展约有一公尺长
Their wings are nearly a metre across.
每年到了十月底
In late October every year,
黄果蝠会展开 横越森林树冠层的漫长旅程
they set off on a long journey across the forest canopy.
蝠群的数目 从几百只变成几千只
Flocks of hundreds become thousands.
几万只变成几十万只
And tens of thousands become hundreds of thousands.
黄果蝠的飞行能力高♥强♥
They are fast and powerful fliers
短短几个晚上 就可以飞一千多公里
and can travel a thousand miles in just a few nights.
它们怎么知道 迁徙的时间和目的是个谜