听力文本

It's astonishing that these extraordinary cave dwellers manage to survive at all.
这些奇异的洞栖生物能如此成功地生存，的确令人称奇
But one cave is so inhospitable that one would not expect it to contain any life whatsoever.
可是有一个洞穴的环境过于险恶，不管什么生物似乎都不可能在那里生存。
The water flowing out of the Villa Luz cave in Mexico is actually coloured white with sulphuric acid.
从墨西哥露兹别墅山洞流出来的水，竟然被硫酸染成了白色
Explorers entering this dangerous cave must wear respirators and carry monitors.
探险家们进入这个危险的山洞时，必须戴上防毒面具，并携带通话器。
Poisonous gases rise to fatal levels so quickly that an early warning system is essential.
有毒气体很快就会达到致命的程度，所以即时预警设备是最重要的。
Bats survive by staying close to the skylights, but venturing deep into the cave is very dangerous indeed.
蝙蝠之所以能生存是因为它们始终呆在天窗附近，但是深入洞穴必然极度危险。
The source of these toxic fumes lies several miles below.
这些毒气的源头位于地下几英里处

Hydrogen sulphide gas bubbles up from oil deposits in the Earth's crust.
硫化氢气体从地壳内的油气储层中溢出
It mixes with oxygen in the water and forms sulphuric acid.
与水中的氧发生化合反应，产生了硫酸。
These are not the sort of conditions in which you would expect to find fish.
鱼类似乎不太可能生活在这种环境中
Yet these cave mollies seem to thrive, despite the acid and the low levels of oxygen.
然而这些洞栖帆鳍鳉看上去却是悠然自得，尽管这里是酸性低含氧量环境。
There is, in fact, more life here than anyone would think possible,
事实上，这里的生物数量远比人们预料的更多，
but the biggest surprise is something altogether more bizarre.
不过更大的惊奇莫过于那些更奇怪的东西。

视频及简介

洞穴是不受阳光控制的生物栖息地之一，但这并不意味着那里就不存在野生生物。本集节目将深入洞穴内神秘而永恒的黑暗，探索山洞、洞穴和隧洞中未知的地下世界。