我们星球上的生命（2023）

he sneaks straight in.
现在雄性领袖以为 自己不是在保卫一只雌性
The alpha now thinks he's guarding not one female...
而是两只
but two.
它不知道这狡猾的年轻闯入者
He's unaware that this sly young interloper
正在与自己选择的伴侣交♥配♥
is mating with his chosen partner.
非凡的智慧和卓越的感官
Their exceptional intelligence and remarkable senses
帮助头足动物 占据了地球上每一片海洋
have helped cephalopods colonize every ocean on Earth.
但是在浅海中
Yet, in the shallows,
它们却极少像高大的祖先那般 成为顶级捕食者
they are rarely the top predators their towering ancestors once were...
因为在古老的海洋中
because in the ancient seas,
即将发生权力转移
there was to be a changing of the guard.
（3.74亿年前）
大融化7000万年之后
Seventy million years after the great melt,
进入泥盆纪时期
in a period known as the Devonian,
脊椎动物开始行动
the vertebrates made their move.
这是邓氏鱼
This is Dunkleosteus...
是微小的阿兰达甲鱼的后代
a descendant of the tiny Arandaspis.
但这身长九米的鱼绝非弱者
But at nine meters long, this fish is no underdog.
即便在幼年期 仅有一半大小 也是可怕的捕食者
Even its young, barely half its size, are fearsome predators.
这条幼鱼在蓝色的海洋中有所发现
And this juvenile has spotted something out in the blue.
菊石
Ammonoids,
今天深海鹦鹉螺的近亲
close relatives of today's deep-sea nautilus.
作为脊椎动物
Being a vertebrate,
邓氏鱼的速度能够追上菊石
Dunkleosteus has the pace to catch up with them.
但是菊石也有自己的本领
But the ammonoids boast a trick of their own...
喷射推进
...jet propulsion.
刚好能够摆脱这条年轻的鱼
Just what it needs to outmaneuver the young fish.
它开始绕圈
As it starts to circle...
菊石也绕圈
the ammonoid does the same...
用壳保护自己的身体
shielding its body with its shell.
在过去 这种防御会有效果
Once upon a time, this defense would have worked.
但是邓氏鱼 拥有自己微小祖先所没有的武器
But Dunkleosteus has a weapon its tiny ancestors did not.
颌
Jaws.
它能咬住并咬碎猎物
It can bite down and crush its prey.
只要找到合适的角度就行
As long as it can find the right angle.
菊石很幸运
Luckily for the ammonoid,
幼鱼的颌尚不够强大 无法咬破它的壳
the juvenile's jaws are not yet strong enough to break its shell.
但成年邓氏鱼可以
But the adult's are.
颌搭配脊椎是胜利的组合
The pairing of backbones with jaws was to prove a winning combination.
如此完美 以至于从这一刻开始
So perfect that, from this moment on,
脊椎动物将永不回头
the vertebrates would never look back.
今天存在超过三万种鱼
Today, there are more than 30,000 species of fish.
是头足动物的40倍
Forty times as many as the cephalopods.
虽然它们的多样性非同一般
While their variety is remarkable...
但每一种都具有这种完美的搭配
each still has that perfect pairing.
脊椎使它们拥有速度和力量
Backbones give them speed and power...
不论它们的大小如何
no matter their size.
而颌则为它们提供了咬的能力
While jaws give them bite.
但是颌的作用不止于此
But there is more to jaws than that.
有的鱼用颌来保护自己的卵
Some fish use them to protect their eggs.
有的鱼用颌来吸引配偶
Others to attract a mate.
还有勃氏新热鳚
Then there's the sarcastic fringehead.
它不光用颌来抓螃蟹
He doesn't just use his to catch crabs.
还用颌来展现令人生畏的实力
He also uses them for one of the most intimidating displays in nature...
以清除领地上的竞争者
to rid his patch of rivals.
对这些鱼来说 大小决定一切
For these fish, size is everything.
巨大的颌令勃氏新热鳚 统治着它的海底地带
Big jaws have let this fringehead rule his strip of seafloor,
但也使另一种更恶名昭彰的鱼类 统治海洋
but they've also allowed a more infamous group of fish to rule the waves.
它们最早出现在四亿多年前
They first appeared more than 400 million years ago
自那以来 一直威名显赫
and have been feared ever since.
它们就是
They are
鲨鱼
the sharks.
在脊椎与颌的胜利组合之外
To the winning combination of backbone and jaws,
它们还加入了异常敏锐的感官
they've added senses so sharp
能够在数百米外侦测猎物
they can detect prey from hundreds of meters away.
许多鲨鱼也拥有体型及力量优势
With many also boasting size and strength,
是近乎完美的海洋捕食者
they are as close to perfection as an ocean predator can get.
在西澳大利亚海域
In the sea off Western Australia,
这些鱼聚集在一起以寻求保护
these fish are balled together for protection.
但鲨鱼暂时按兵不动
But the sharks hold back...
因为它们有一个特别的进攻计划
because they have a special plan of attack.
鲨鱼采取团队作战
Appearing to work as a team,
一些鲨鱼从下方向上进攻 将小鱼逼向海面
some of the sharks rise from below to trap the fish against the surface.
另一些鲨鱼从侧面进攻
Others come in from the side,
将鱼群赶到远离开阔海洋的浅水区
corralling the shoal away from the open ocean and into the shallows.
现在 数以百计的鲨鱼
Now numbering in their hundreds,
在等待时机
the sharks play for time...
它们的猎物变得越来越疲惫
as their prey get ever more tired.
这是一种经过数百万年 得以完善的捕猎技巧
It's a hunting technique that has been honed over millions of years.
眨眼之间 大屠♥杀♥开始
But the carnage starts in the blink of an eye.
大融化之后几乎未曾改变
Virtually unchanged since the great melt,
鲨鱼王朝 一直是史上最成功的王朝之一
sharks are one of the most successful dynasties in history.
但它们的崛起归功于 最强大竞争对手的灭亡
But they owe their rise to the fall of their greatest rivals.
（3.6亿年前）
回到古代海洋
Back in the ancient seas,
邓氏鱼已经统治了2000万年
and Dunkleosteus had reigned for 20 million years.
它们是如此凶悍的捕食者
So vicious a predator
以至于早期的鲨鱼也无法与之匹敌
that not even early sharks could compete.
但邓氏鱼即将遭受毁灭性打击
But Dunkleosteus was to suffer from a devastating quirk of fate...
这一切都源于浮游生物
...caused by plankton.
数十亿年前
Billions of years earlier,
浮游生物是动物生命的催化剂
plankton had been the catalyst for animal life.
但是现在 它几乎将动物生命带入终结
But now, they would almost bring it to an end.
海洋养分激增
A sudden surge in ocean nutrients
导致浮游生物数量增加
caused the population of plankton to increase...
规模空前
on an unprecedented scale.
当浮游生物遍布阳光照耀的浅水时
As it spread through the sunlit shallows,
这浓汤般的水体开始腐烂
this thick soup began to rot...
导致海洋中的氧骤减
causing the ocean's oxygen to plummet.
没有了这种不可或缺的生命成分 动物开始窒息
Without this critical ingredient for life, animals started to suffocate.
对于那些无法逃离这脏水的生物来说 结果只有一个
For those unable to escape the sludge, there was only one possible outcome.
灭绝
Extinction.
邓氏鱼 是从我们星球上消失的众多生物之一
Dunkleosteus was one of many to be lost from our planet.
世界各地的海岸线上尸体遍布
Across the world, coastlines became littered with the dead.
只有少数幸运者得以存活
Only the lucky few, including early sharks,
其中就包括早期的鲨鱼
were able to survive.
80%的海洋生物因此死亡
In all, 80% of marine life was wiped out in this,
这是世界上第二次大规模灭绝
the world's second mass extinction.
但这还只是故事的一半
And yet this is only half the story.
引起浮游生物暴增的养分
The nutrients that caused the plankton explosion
并非来自海洋
didn't start out in the sea.
而是来自陆地
They were carried there from the land...
在史上最伟大的一个事件期间 由植物释放而出
...released by plants during one of the most amazing events of all time...
这个事件就是地球的绿化
...the greening of planet Earth.
曾经的火山荒原
What was once a volcanic wasteland
如今生机盎然
was now overflowing with life.
这个新世界提供了机会
And this new world offered opportunity.
植物铺平了道路
For where plants had paved the way,
动物也将跟随而来
animals would follow.
不久之后 主宰陆地的竞赛将揭开帷幕
And before long, the race to dominate the land would begin.