我们星球上的生命（2023）

数十亿年来
For billions of years,
我们世界的许多地方 都极不适宜生存
much of our world was fiercely inhospitable...
这些地方遭到自然因素和力量的摧残
...ravaged by the elements and the forces of nature.
但本集将讲述的是海浪下发生的故事
But this is the story of what was happening beneath the waves.
这里远离风暴 生命已经扎根
Here, shielded from the storms, life had taken hold...
而且即将永远改变我们的星球
...and was about to change our planet forever.
《我们星球上的生命》
双语合并：村儿南
第 2 章：第一前线
（24亿年前）
很久很久以前
Far back in the depths of time,
地球的样貌与现在完全不同
Earth looked nothing like the world we know today.
当时的地表将近90%由水覆盖
Nearly 90% of its surface was water,
但当时的地球并非蓝色
yet this was no blue planet.
恰恰相反 巨大的甲烷云将大气变为黄色
Instead, vast clouds of methane had turned the atmosphere yellow.
陆地上的情况更糟
On land, conditions were even worse.
火山已经喷发了数百万年
Volcanoes had been erupting for millions of years.
其爆♥炸♥声
Their explosive power,
是那个原本寂静的世界中 为数不多的声音之一
one of the few sounds in this otherwise silent realm.
当时的世界只有 有毒气体和熔岩河流
With the world made up of nothing but toxic air and rivers of molten rock...
我们所知的生命不可能存在
life as we know it was impossible.
但是在史前的海洋中
But out in the prehistoric seas,
有一些情况正在酝酿
something is stirring.
水面下漂浮着大量浮游生物
Beneath the surface hangs a great swathe of plankton.
这样微小的细胞 刚刚进化出了一样新的东西
Microscopic cells like these have just evolved something new,
光合作用
photosynthesis.
这意味着 它们能够利用太阳的能量生长
This means they can harness the sun's energy to grow,
这是一项如此重要的突破
a breakthrough so important
以至于有朝一日 地球上一切植物都将由其催生而出
that plankton will one day give rise to every single plant on Earth.
但这并不是全部
But that's not all.
光合作用的副产品之一是一种气体
One byproduct of photosynthesis is a gas,
这是动物生命存在不可或缺的元素
the missing ingredient for animal life to exist...
氧气
...oxygen.
在将近20亿年的时间里
For nearly two billion years,
浮游生物产生了大量氧气 使我们的星球发生了巨大改变
plankton produced so much oxygen that it transformed our planet.
地球不再充满敌意 而是成为了一个新的世界
No longer hostile, Earth became a new world,
在这里 生命终于可以自♥由♥绽放
where life could finally run wild.
数百万年后的今天
Today, millions of years later,
我们依然可以一窥 之后一波生命浪潮的模样
it's still possible to get a glimpse of what that next wave of life was like.
因为在浅海的某些地方
Because in some parts of our shallow seas...
生命仍然与原始时期类似
life still resembles that more primitive time.
虽然可能看起来不像
They may not look like it...
但这些动物
but these are animals...
与最早的复杂生物形态非常相似
very similar to the first complex life forms.
多数为软体且根植于海底
Most are soft-bodied and rooted to the seafloor.
都有感官
All have senses.
有一些甚至能看到周围
And some can even see their surroundings.
许多通过滤食来获取食物
Many get their food by filter-feeding,
挑选出浮游生物
picking out plankton,
有时方法极为奇特
sometimes in the most curious of ways.
但这里的动物并非全都困于一地
But not all animals here are stuck in one place.
有一些能够移♥动♥
Some can move,
探索海底
exploring the seafloor
数百万年前它们富有探索精神的亲戚们 也是这样做的
like their pioneering relatives millions of years ago.
这些浅海看起来可能像是伊甸园
It may seem like these shallows are a kind of Eden,
是生命的安全港
a safe haven for life.
但这里并不是天堂
But this is no paradise.
在加利福尼亚海域
Living off modern-day California...
如今生活着一种彩虹裸鳃
this is a rainbow nudibranch.
它缓慢的本性中 隐藏着邪恶的一面
And its sluggish nature hides a sinister side...
因为与其祖先一样
because, like its ancestors,
它在这里是为了捕猎
it's here to hunt.
它适应了掠食的生活
It's adapted to a life of predation.
它所选择的猎物是
And its prey of choice,
海葵
anemones.
但与最早的捕食者一样
But like the very first predators,
裸鳃仍有改进的空间
the nudibranch has room for improvement...
因为在这里
...because here,
把握时机…
timing...
至为重要
is everything.
对于猎手来说 幸运的是
Luckily for the hunter,
它的猎物根植于海底
its prey is anchored to the seafloor
无法永远隐藏
and can't hide forever.
海葵的命运会是如何？
The anemone's fate?
从内部被吃掉
To be eaten from the inside out.
（5.3亿年前）
捕食者的出现 是古代海洋中的一次颠覆性转变
The arrival of predation was a seismic shift in the ancient seas.
猎物必须适应变化
The hunted had to adapt
否则就会面临灭绝的风险
or risk extinction.
有一群生物以前所未见的方式 适应了这种转变
And one group adapted in a way never seen before.
尽管是单独个体的动物
Despite being single animals,
但还是能够分离成数层个体层
they were able to separate into layers of individuals,
然后独♥立♥出来
that then broke free.
那就是水母
Jellyfish.
5.3亿年前
530 million years ago,
它们是第一种从海底逃离 并开始游泳的生物
they were the very first animals to escape the seafloor and swim.
但是捕食者已经无处不在
But predators were already everywhere.
这些海葵装备有带毒的鱼叉
Armed with venomous harpoons,
能够快速解决小水母
these anemones make quick work of baby jellyfish.
而且它们的数量如此之多
And they are so abundant
逃脱似乎是不可能完成的任务
escape seems impossible.
被抓住了
Caught.
但不会太久
But not for long.
终于自♥由♥了
Free at last.
由于会游泳
Thanks to their ability to swim,
水母率先冒险离开浅海
jellyfish were the first to venture out of the shallows
进入巨大的蓝色海洋
and into the big blue.
在这里 鱼类尚未进化
Here, with fish yet to evolve,
水母完全摆脱了被捕食的危险
jellyfish were entirely free of predation.
随着时间的推移 其他生物也会跟随而来
In time, others would follow.
但是五亿多年前
But more than half a billion years ago,
广阔的海洋属于它们
the open ocean belonged to them.
（5.08亿年前）
对于那些仍困于海床上的生物来说
For those still stuck on the seabed,
逃避被捕食需要一种不同的方式
escaping predation required a different approach.
这种奇怪的生物
This curious creature
是三叶虫
is a trilobite.
它的突破性适应特征就是护甲
And its breakthrough adaptation, armor.
三叶虫 是一个全新王朝中的首批生物之一
Trilobites are one of the first in a brand-new dynasty,
节肢动物
the arthropods.
它们进化出了外骨骼
They've evolved an external skeleton,
这是一种保护其柔软内部的盾状外壳
a shield-like shell that protects their soft insides.
在这些水域中
And in these waters,
它们确实需要外壳
they need it.
这是奇虾
This is Anomalocaris.
一种外观怪异的动物
A bizarre-looking animal,
顾名思义 它名字的含义就是“奇怪的虾”
its name translates as "the abnormal shrimp."
在5.08亿年前的热带浅海中
And in the tropical shallows 508 million years ago,
它是世界上第一种顶级捕食者
it's the world's first apex predator.
尽管三叶虫有护甲 但是保持隐蔽仍然是明智的做法
Despite the trilobite's armor, it makes sense to keep out of sight.
但是由于远离峡谷 无处可藏
But away from the canyons, there's nowhere to hide...
因为这位猎手的特别之处在于…
because what makes this hunter so special...
速度
...is its speed.
与水母不同 奇虾游速快且方向准确
Unlike jellyfish, Anomalocaris can swim with both direction and pace.
但这也并不总是足够的
But that isn't always enough...
因为当被逼入绝境时 三叶虫的护甲就开始发挥作用
because when cornered, the trilobite's armor comes into its own.
它卷成一团 变得无懈可击
Rolling into a ball, it becomes completely impenetrable.
即便奇虾也无可奈何
Even for the abnormal shrimp.
威胁消除之后 三叶虫继续踏上快乐的旅程
With the coast clear, the trilobite continues on its merry way once more.
它在寻找 古代海洋中最壮观的景象之一
It's searching for one of the ancient ocean's greatest sights...
三叶虫交♥配♥地
...the trilobite mating grounds,
数以千计的三叶虫来到这里繁衍后代
where thousands come together to breed.
在生命的故事中 护甲是如此成功
In the story of life, armor has been such a success