地球脉动（2006）

但却能得到丰厚的回报
but the rewards are great.
洞金丝燕的纯白燕窝
The pure white nests of cave swiftlets
是燕窝羹的主要成分
are the main ingredient of birds' nest soup
每克燕窝的价值堪比白银
and gram for gram are worth as much as silver.
燕窝被摘去后 金丝燕很快又会再吐一个
As soon as its nest is removed a bird will immediately build another.
所以 只要这种利润可观的 采摘行为得到适当控制
So, as long as this valuable harvest is properly controlled,
燕群仍旧可以长盛不衰
the colonies will continue to flourish.
婆罗洲的这些洞窟是世界上最大的洞穴
These Bornean caves are among the biggest in the world
它们仍在不断扩大
and they're still getting bigger
因为每年雨水都会侵蚀掉少许石灰岩
as each year rainwater eats away a little more limestone.
可是洞里的水不光只是侵蚀
But water in caves doesn't only erode.
它们还能造景
It also builds.
这些水中含有溶解的碳酸钙
This water is loaded with dissolved limestone
当它与洞内空气接触时
and when it meets the air in the cave
其中的一些就会沉淀为一种矿物
some of that is deposited as a mineral -
方解石
calcite.
随着它的积累
As it builds up
方解石形成了悬在洞顶上的装饰物
so the calcite forms decorations that hang from the ceiling -
钟乳石
stalactites.
每滴水珠只会留下极少量的方解石微粒
Each drop leaves behind only a miniscule amount of calcite,
但随着时间的推移 它们变成了最引人入胜的景观
but over time the process can produce some spectacular results.
若是水从洞顶滴落的速度较快
If the water seeps though the ceiling quickly,
方解石就会在洞穴地面上沉积
then the calcite is deposited on the floor of the cave
最后形成石笋
and that creates stalagmites.
水流和气流的变化
Variations in water flow and the air currents
造就了千姿百态的溶洞地形 但它们的形成过程都是一样的
produce an infinite variety of forms, but all are created by the same process -
都是由水溶碳酸钙缓慢沉淀而来
the slow deposition of dissolved limestone.
钟乳石与石笋相遇后
And when stalactite meets stalagmite
便形成了石柱
a column is born.
北美洲卡尔斯巴德溶洞中的这些构造
Structures like these in North America's Carlsbad Cavern
经历了数千年的形成过程
can take many thousands of years to develop.
但有时洞穴内的这些活动会完全停止
But sometimes the formations in a cave stop growing altogether.
墨西哥的这些水洞 几千年来几乎保持不变
These flooded caves in Mexico have remained virtually unchanged for thousands of years.
自从上一个冰川期以来 它们便已和外界隔绝
Since the last Ice Age they've become cut off from the outside world.
然而它们对地面上的生物 却有着极其深远的影响
Yet their impact on life on the surface has been huge.
500年前 它们维系着 一个世界上最伟大的文明
500 years ago they supported one of the world's great civilisations
玛雅
the Maya.
墨西哥的尤卡坦半岛 没有河流、湖泊和小溪
Mexico's Yucatan Peninsula has no rivers, lakes or streams
因此玛雅文化完全依赖于沼穴 ——地下水洞的入口
so the Maya relied on the cenotes - the flooded entrances to the water-filled caves.
这些水潭是整个地区 唯一的露天淡水资源
These flooded shafts are the region's only source of open fresh water.
沼穴于是成了巨大的淡水井
The cenotes are, in effect, gigantic fresh water wells.
这里远离给予生命的阳光
Away from the life-giving rays of sunshine
似乎不太可能会有植物
one might not expect to find plants.
但是在黑暗的洞穴通道内
But in the darkness of the cave tunnels
大型热带树木的根系 却已穿透石灰岩裂缝
roots of giant tropical trees have pushed their way through cracks in the limestone
伸入到水洞之中
to reach the flooded caverns.
如果没有这些水
Without this water
尤卡坦半岛的森林不可能长得如此茂盛
the Yucatan's forest could not grow so luxuriantly.
玛雅人固然知道 它们的生活离不开这些水
The Maya knew that their lives depended on this water,
但只有借助现代科技
but it's only with the help of today's technology
我们才能完全了解 这些地下水道的重要性及其规模
that we've come to appreciate the full significance and scale of these flooded passageways.
人们迄今为止已绘制了350英里的 尤卡坦半岛地下水系图
So far, more than 350 miles of underwater galleries in the Yucatan have been mapped,
但仍旧无人知晓 这个地下水世界究竟有多大
but still nobody yet knows the true extend of this subterranean waterworld.
以及它形成的原因
And with good reason.
地下水洞是出了名的危险
Underwater caving is notoriously dangerous.
最近的出口可能远在 几百米之外或者更远的地方
When the nearest exit may be hundreds of metres or more away,
在这里 耗尽氧气将是致命的
running out of air down here would be fatal.
为了避免迷路
To avoid getting lost
潜水员必须随身携带一捆轴线
divers carry with them a spool of string.
这成了它们的救生索
It becomes their lifeline -
绝对如此
literally.
这根线同时也是测量尺
The string also doubles as a measuring tape -
在墨西哥的这个地方 这种科技被用来 测绘世界上最大的地下水洞
a technique that has been used here, in Mexico, to chart the largest underwater cave in the world -
全长达100多英里
all 100 miles of it.
洞穴探险需要不时挤过 一些狭窄的岩石缝隙
Cave exploration often requires you to push yourself through narrow gaps in the rock.
洞穴专家称之为“瓶颈”
Cavers call such places 'squeezes.'
“瓶颈”越是狭窄
The tighter the squeeze,
便越有可能损坏一些重要的生存设备
the greater the chance of damaging some vital life-support system.
在这种情况下 潜水员很容易迷失方向
In these conditions a diver could easily become disorientated
而这将导致送命
and that could be fatal.
地下水洞还会以别的方式戏弄你
The flooded caverns can play tricks on you in other ways.
这看上去像是空气
What seems like air,
不对
isn't.
它只是另一种水
It's just another kind of water.
这里是盐跃层
This is a halocline -
淡水与咸水的交汇处
a meeting of fresh and salt water.
咸水来自海洋 比重较重 来自丛林的淡水在其上方流动
Fresh water from the jungle flows over the heavier salt water from the sea.
咸水层的含氧量很低
The saltwater layer is extremely low in oxygen
对动物而言是极为困难的生境
making it a particularly difficult place for animals to live.
但有些动物却能在此生存
Yet some have managed it,
例如桨足虫——一种最古老的甲壳动物
like the remiped, one of the most ancient of all living crustaceans.
玛雅人知道沼穴的重要性
The Maya understood the importance of the cenotes,
但他们从不知道这些水下通道 其实是地下河的入口
but they could never have known that these flooded passageways were actually the beginning of subterranean rivers,
它们最终都流向大海
all of which eventually flow out to the sea.
咸水与淡水不同 不会溶解石灰岩
Salt water, unlike fresh water, does not erode limestone,
所以大部分海洋洞窟 是在海浪的机械冲击下形成的
so most sea caves are created by the mechanical pounding of the waves.
新西兰坡·骑士岛的 岩礁下布满了海蚀洞
The rocky outcrops of New Zealand's Poor Knight Islands are riddled with sea caves
与婆罗洲的洞窟一样
and just like those in Borneo
它们也成了许多动物的重要庇护所
they have become important shelters for many species.
经过一天开放水域的觅食之后
After a day feeding in the open water
大群雀鲷返回到洞窟中
vast shoals of demoiselle fish return to the caves,
这里是它们躲避天敌的地方
which they use as a refuge from predators.
对于这些鱼来说 洞穴是理想的过夜场所
For these fish the caves are a night time retreat,
但它们并非这里的唯一住客
but they're not the only commuters in here.
这里还有其它 按照不同日程表生活的鱼
There are other fish working to a different schedule.
大眼鲷相当于蝙蝠
The bigeyes are the equivalent of bats.
它们每天晚上出洞觅食
Night feeders leave the cave each evening.
和所有洞穴动物一样
And like all cave commuters
它们在出发阶段最容易遭受攻击
they are most vulnerable at the scheduled time of departure.
当大群蝙蝠密集地通过瓶颈出口时
A bottleneck funnels these exiting bats into dense concentrations
很容易引起其它动物的注意
attracting the attention of others.
蝙蝠能利用回声定位觉察到蛇
The bats can detect the snakes using echolocation,
而蛇则完全处于黑暗之中
but the snakes are literally in the dark -
它们看不见任何东西
they can see nothing.
这种攻击更像是在碰运气
The strikes seem to be largely hit-and-miss,
不过蛇也有自己的秘密武器
but the snakes have a secret weapon.
它们实际上能感觉到 每一只飞过的蝙蝠
They can actually sense each bat flying past.
位于头部的“热眼”能觉察到 飞行中的蝙蝠散发出的热量
Receptors in the snake's head pick up the heat given off by the flying bats,
正如这幅热影像所示
as this thermal image shows.
每一只蝙蝠在蛇“眼”前都是活灵活现
To the snakes the bats are apparently glowing
这也给了它们瞄准目标的机会
and this gives them something to aim at.
这是洞栖动物必须付出的代价
This is the price that these cave commuters must pay
以换取它们白天在陆地上的庇护
for their daytime sanctuary on the ground.
难怪其它洞穴生物 要终生居住在洞穴中
Small wonder then that there are other cave dwellers that stay put.
很多洞穴都和岛屿一样
Many caves are like islands -
与外界及其它洞穴隔绝
cut off from the outside world and from other caves.
这种孤立环境导致进化产生 各种各样奇怪的生物
This isolation has resulted in the evolution of some various strange creatures.
它们都是洞穴专家
They are the cave specialists -
穴居动物——从不出洞并且 永远不见天日的动物
troglodytes, animals that never emerge from the caves or see daylight.
泰国的这些穴居动物
These troglodytes from Thailand
可能是地球上最奇特的动物
are possibly the most specialised creatures on Earth
因为它们只生活在洞穴瀑布中
for they live only in cave waterfalls.
世界上所有的洞穴天使鱼
The entire population of these cave angel fish
可能只存在于两个较小的洞穴中
seems to be restricted to just two small caves.
其它穴居动物也是同样的情况
It's the same story with other troglodytes.
世界上可能只有不到100只 野生洞栖童态河溪螈
There may well be less than a hundred Texas cave salamanders in the wild.
而伯利兹白蟹是另一个 洞穴生态系统中的特有物种
And the Belizean white crab is another creature that is unique to just one cave system.
由于一直生活在黑暗之中
Living in perpetual darkness
它们不仅失去了皮肤色素
they have all not only lost the pigment in their skin,
眼睛也退化了
but also their eyes.