一直以来 鲸鱼都是最庞大的动物
Whales are the biggestanimals of all time.
他们比大象 长毛猛犸象 甚至恐龙还要重
Heavier than elephants, woolymammoths, and even dinosaurs.
但它们并非一直都是海洋巨头
But they weren’t alwaysthe titans of the sea.
让我们先穿越回5000万年前
Let’s rewind the clockaround 50 million years.
在那里 根本没有鲸鱼
No, you won’t find any whales here.
你得先上岸
You have to go ashore.
你会看到最早的鲸鱼 巴基鲸
Meet Pakicetus, the very first whale.
地球上的生物用了数百万年
Life on earth spent millionsof years clawing its way
才成功从海洋里爬上岸
out of the oceans.
但鲸鱼的海洋之路却反其道而行之
But whales took all that effort and threw it out the window.
四千至五千万年前
From 50 – 40 million years ago,
它们的四条腿逐渐退化为鳍
they traded in theirfour legs for flippers.
事实上 直至今日 有些鲸鱼仍保留着
In fact, some whales today still have
后腿退化后的骨头
leftover bones of hind legs.
一旦进入海洋 体重与重力的关联
Once submerged, their weight under gravity
就没那么重要了
no longer mattered.
因此 理论上来说 它们可以长成庞然大物
So they could theoreticallygrow to enormous proportions.
事实也的确如此
And they did.
如今 一头蓝鲸的重量已是巴基鲸的10000多倍了
Today, a blue whale is10,000 times more massive than the Pakicetus was.
但这种变化并非循序渐进
But this transformation wasn’t as gradual as you might think.
实际上 约在3700万年前
In fact over the next37 million years or so,
鲸鱼的进化开始多样化
whales grew increasingly diverse,
但它们的体型仍然很小
but their size remained small.
例如 第一代以鲸须代替牙齿的鲸鱼中
For example, one of the first whales
最小的只有18英尺长
with baleen instead ofteeth was only 18 feet long,
因此它们极易成为食肉动物如大鲨鱼的腹中之物
making them easy prey forpredators, like giant sharks.
直至大约三百万年前
It wasn’t until aroundthree million years ago
鲸鱼迎来了它的高光时刻——冰河时代
that an ice age tipped thescales in the whales’ favor.
海洋温度和洋流的改变
Ocean temperatures and currents shifted,
让大量浮游生物及捕捉鲸爱吃的鳞虾出现
sparking concentrated swarms of plankton, and plankton-seeking krill.
这些全是须鲸的自助餐
It was an all-you-can-eatbuffet for the baleen whales,
因此 须鲸才能越长越大
who grew larger as a result.
须鲸长得越大 就可以游得更远
And the larger they became,the farther they could travel
去寻找更多食物 进而长得更多
in search of more food to grow even more.
结果可以预见
You can probably see where this is going.
三百万年后 例如座头鲸
Three million years later,humpbacks, for example,
迁移路程最长的哺乳动物之一
have one of the longestmigrations of any mammal on earth
每年的旅程已经超过了5000英里
traveling over 5,000 miles each year.
因此 现在鲸鱼的体积达到了史上最大
As a result, modern whales arethe largest they’ve ever been in history.
蓝鲸是体积最大的生物
Take the biggest of thebunch, the blue whale.
它比波音757还重的多
It weighs more than a Boeing 757,
肚脐就有盘子那么大
has a belly button the size of a plate.
如果我们把蓝鲸的血管
And its network of blood vessels, if you
连成一条直线 这条线
laid them out in a line, could stretch
是冥王星到太阳来回距离的
from Pluto to the sun and back,
2.5倍长
over two and a half times.
事实上 科学家认为蓝鲸的最大体积
In fact, the largestblue whales are so huge
已经达到了生理极限
that scientists think theymay have hit a physical limit.
蓝鲸张开大嘴吞食时
When they open their wide mouths to feed,
咽下的水足以充满一间大客厅
they engulf enough water tofill a large living room.
因此它闭上嘴巴就得用去十秒钟
So it can take as long as 10 seconds to close them again.
科学家估计一旦蓝鲸的体积达到110英尺长
Scientists estimate oncea whale is 110 feet long,
它们就不能在猎物逃跑之前闭上嘴巴
it can’t close its mouth fastenough before prey escapes.
因此我们可能正与史上最大的动物共存于地球
So it’s possible we’re livingamongst the largest animal that will ever exist.
还好它们的主食为鳞虾
Lucky for us, they mostly just eat krill.
鸣谢尼克·佩尔森
This was made in largepart thanks to Nick Pyenson
及其新书《探秘蓝鲸》
and the information in hisnew book,”Spying on Whales.”