It's easy to forget how vast and deep the ocean really is.
我们很容易忘记海洋到底有多广阔，有多深。
About 60% of it is actually a cold and dark region known as the deep ocean.
大约60%的海洋是冰冷黑暗的，也被称为深海。
And it reaches down to 11,000 meters.
它深达11000米。
Yet, this remote zone is also one of the greatest habitats on Earth,
然而，这一偏远的地带却是地球上最大的栖息地之一，
harboring a huge diversity of life, from giant squids and goblin sharks to minuscule animals smaller than a millimeter.
容纳了丰富的生命多样性，从巨型鱿鱼和妖精鲨鱼到小于一毫米的微型动物。
How do so many species thrive in this underwater world?
这么多种生物是如何在这个水下世界繁盛起来的呢？
Over the decades, intrepid scientists have ventured there to find out.
在过去几十年里，勇敢的科学家们曾冒险进入这片区域去寻找答案。
Traveling down through the water column, pressure increases and light begins to wane.
穿越过整个水层，随着深度增加水压逐渐增大，光线开始变得微弱。
At 200 meters, photosynthesis stops and temperature decreases from surface temperatures by up to 20 degrees Celsius.
到达200米时，光合作用停止，温度比起水面温度可以降低20摄氏度。
By 1000 meters, normal sunlight has disappeared altogether.
到1000米时，日光完全消失。
Without light, life as we know it seems impossible.
没有了光线，我们所知的生命似乎无法存在。
That's why in 1844, the naturalist Edward Forbes wrote his Azoic Theory, Azoic, meaning without animals.
这也是为什么在1844年，自然学家爱德华·福布斯在他的著作无生学说中写道：无生，意味着没有动物。
Forbes was sure that nothing could survive below 600 meters on account of the lack of light.
由于没有光的缘故，福布斯认定没有生物可以在600米以下的海洋存活。
Of course, the discovery of deep-sea species proved him wrong.
当然，深海生物的发现证实了他是错的。
What Forbes failed to take into account is something called marine snow, which sounds much nicer than it is.
福布斯没有考虑到的是一种叫海雪的东西，这种东西的名字听起来比它实质要美妙很多。
Marine snow is basically organic matter, things like particles of dead algae, plants, and animals,
海雪是一种有机物质，像死去的海藻或动植物的粒子
drifting down into the depths and acting as food for deep-sea animals.
沉入到深海中，并成为深海动物的食物。
Largely thanks to that, abundant life forms exist in the darkness,
得益于此，丰富的生命形式得以在黑暗中存在，
adapting to a harsh reality where only the weird and wonderful can survive.
在如此严酷的环境中，只有最怪异的和最美妙的生命形式得以留存。
Fish with cavernous mouths, spiky teeth jutting from their jaws,
有着洞穴一般巨嘴的鱼类，尖刺状的牙齿从下巴中突出来，
and lamp-like structures protruding from their heads, like the anglerfish which entices prey with its misleading glow.
还有头顶上突出的台灯状结构，还有如通过令人迷惑的亮光吸引猎物的琵琶鱼。
Several sea creatures have perfected this lightning technique known as bioluminescence,
有些海洋生物完善了这项发光的技能，我们称之为生物光，
using it to lure prey, distract predators, or attract mates.
来诱捕猎物，分散捕食者注意或吸引伴侣。

Some creatures use it for camoflauge.
有些生物通过它来伪装自己。
In parts of the water column where only faint blue light filters through, animals bioluminesce to match the glow.
有些水域只有蓝光能被过滤通过，动物们用生物光来配合光线。
Predators or prey looking up from below are deceived by this camoflauge, unable to see the creatures silhouette.
捕食者或猎物从下往上看，会被这种伪装欺骗，无法看到它们的轮廓。
Such otherworldly adaptations also arise from the need to locate and snatch up food before it drifts away.
这种适应性的形成也来自于定位的需求，在猎物遁走前抓住它。
Some sea animals, like jellyfish, comb jellies and salps can migrate between depths partially
有些海洋动物，比如水母、栉水母还有樽海鞘，可以在不同深度水域中移动，
because their 90% water consistency allows them to withstand immense pressure. But they're the exception.
部分原因是它们身体有90%的组成是水，使它们能够忍受巨大的压力。但它们属于特例。
Most deep-sea creatures are confined to a narrow range in the water column
大部分深海生物被限制于一个狭窄的水层区域，
where nutrients are scarce since the food drifting downwards from the surface rapidly sinks to the sea floor.
那里营养稀缺，因为食物从水面下沉，很快沉入海底。
Plunging all the way down, we find more exotic creatures.
越是往下，我们发现越多奇异的生物。
Some take on dwarfism, a trait that transforms them into miniature versions of animals we see closer to the surface.
它们有些是侏儒状态，这是当我们更近的观察表面时，一种将它们转化成迷你版本生物的特征。
It's thought that reduced food availability causes the shrinkage.
减少的食物来源被认为是造成这种体积缩减的原因。
Only a tiny fraction of the food produced at the surface reaches the sea floor,
仅有一小部分水面的食物最终到达海底，
so being small gives animals a low energy requirement and an adaptive advantage.
所以动物的小型体积能够降低能量消耗和更好的适应性的优势。
And yet, the sea is also the land of giants.
然而，海洋也是巨人的家园。
Here, gargantuan squids can reach 18 meters long.
在这里，巨型鱿鱼体长可达18米。
Isopods scuttle around the sea floor like enormous wood lice.
等足目生物在海床表面像木虱一样遁走。
There are long-limbed Japanese spider crabs, and oarfish, whose bodies stretch to 15 meters.
也有长足日本蜘蛛蟹，还有身子可以拉长至15米的桨鱼。
This trait is known as gigantism, and it's something of a mystery.
这一特性被称为巨人症，并仍然是个谜。
It's thought that high oxygen levels may drive extreme growth in some species,
高氧浓度被认为也许促进了一些物种的极端生长，
while the colder temperatures promote longer life spans, giving animals the opportunity to grow massive.
而冰冷的水温延缓了寿命，使得动物们能够长至巨型的身材。
Many of these exotic sea beasts will never experience sunlight.
这些异国海兽中的许多将终生不见光亮。
Some will venture up through the water column to feed, and a few will actually break the waves,
有些会冒险去到其他水层觅食，还有极少的一部分能够真正的突破海浪
reminding us at the surface about the incredible survival skills of the ocean's deepest inhabitants.
到达海面，提醒着我们这些深海居民惊人的生存能力。
Humans still have an astounding 95% of the ocean left to explore.
人类仍然还有难以置信的95%的海洋不曾探索过。
So those depths remain a great mystery.
因此这些深水区域仍然充满谜团。
What other untold wonders lie far below, and which ones will we discover next?
在这下面还有什么未知的奇迹，而我们发现的下一个奇迹又会是什么？