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极端环境中的复杂生命 – 译学馆
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极端环境中的复杂生命

The Most Extreme Complex Life in the World

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[片头]
[♩INTRO]
人类最高定居点位于
The highest permanent human settlement is
秘鲁的一个矿区小村拉林科纳达
a tiny mining village called La Rinconada, in Peru
其海拔高度约为5100米
which is about 5,100 meters above sea level
想想有些人在海拔2500米处就有高原反应
Considering that some people start to get altitude sickness at around 2500 meters
那个高度真的不得了
that’s pretty intense
不过 不是地球上每种生灵都像人类这样娇弱
Not everything on Earth is as restricted as we are, though
你也许听说过硬核细菌
You might have heard of the hardcore microbes
它们能够生活在极高的海拔或最深的海底
that can live at superhigh elevations or the deepest parts of the ocean
但一些极其复杂的生命形式
But there are surprisingly complex forms of life
也可以在这些地方生存
that can survive in those places, too
它们只需一些对极端环境的适应即可
They just need some extreme adaptations to do it
到了更高海拔处 你会立即发觉
The most immediate thing you’ll notice at higher elevations
呼吸变得困难许多
is that it’s way harder to breathe
海拔越高 气压越低
The higher you go, the less air pressure there is
肺吸入氧气变得困难
Your lungs struggle to take in oxygen
你也会产生高原反应
and you can develop altitude sickness
高原反应是因缺乏氧气而导致的一系列症状
where the lack of oxygen causes symptoms like
例如恶心 心跳加速
nausea, a rapid heart rate
情况严重时还会发生脑水肿
and in severe cases, swelling in the brain
然而 在高海拔处待得时间足够长
Spend enough time up there, though
你的身体就会开始适应
and your body will start to adapt
产生更多携带氧气的红细胞
by producing more oxygen-carrying red blood cells
其他高等动物 例如哺乳动物和鸟类 也会有类似问题
Other complex animals, like mammals and birds, can have pretty similar problems
牦牛一般生活在海拔6100米处
And yet, yaks, regularly hang out at elevations of 6,100 meters
为了应对高海拔 它们进化出了更大的胸腔 肺和心脏
To cope with that, they’ve evolved larger chests, lungs, and hearts
以及如旧地毯般厚厚的皮毛来抵御严寒
as well as thick, shaggy coats to help deal with the bitter cold
研究人员也发现 牦牛的基因组发生了一些变化
Researchers have also discovered a bunch of changes to their genetic code
这些变化让它们更好地适应高海拔
that help them survive up there
例如控制身体的应激反应
like by controlling their body’s stress response
在氧气不足时
when they’re low on oxygen
鸟类可以达到更高的海拔
Birds can go even higher
例如 斑头雁
The bar-headed goose, for example
一般会迁徙到海拔高达7000米的喜马拉雅山顶
regularly migrates over the Himalayas at altitudes up to 7,000 meters
根据资料记载 达到最高海拔的脊椎动物是秃鹫
And the highest known vertebrate ever recorded is Rüppell’s griffon vulture
1973年两名飞行员驾驶飞机于海拔11000米处
In 1973, two pilots flying at 11,000 meters
这个高度比珠穆朗玛峰的最高点还要高2500米
that’s 2,500 meters higher than the top of Mount Everest
他们遭遇了一桩突发事件
made a sudden and terrifying discovery
当时一只鸟被吸入飞机引擎中 致使飞机紧急迫降
when a bird got sucked into the plane’s engine, forcing an emergency landing
对大家来说这是倒霉的一天
Not a good day for anybody involved
我们还不能完全搞懂鸟类是如何生活在如此高的海拔的
We don’t fully understand how these birds do it
但是研究发现斑头雁和秃鹫都产生了基因突变
but both the bar-headed goose and Rüppell’s griffon vulture have genetic mutations
这些突变使得血液中的血红蛋白能携带更多氧气
that allow the hemoglobin proteins in their blood to hold onto more oxygen
研究人员还发现 当氧气不足时
Researchers have also found that when they’re low on oxygen
斑头雁可以呼入呼出更多空气
bar-headed geese can move more air in and out of their lungs
比我们已知的物种都要多
than any other species we’ve ever studied
比11000米更高的海拔处是微生物的领域
Any higher than that and you start to get into the realm of microbes
例如 在雷雨云顶部发现有细菌存在
Bacteria, for example have been found at the tops of storm clouds
距地球表面高达15千米处也发现了细菌
and up to 15 kilometers above the surface of the Earth
我们也不知道这些细菌是如何生存的
We don’t yet totally understand how they survive, either
但是在地球上一些极端环境中发现细菌也并非罕见之事
but it’s not too uncommon to find microbes in some of the most extreme environments on Earth
如果你是一个形体微小 结构简单的生物体
It doesn’t take quite as many genetic changes to adapt
要适应环境也不需太多基因突变
when you’re a super tiny simple organism
有趣的是 在极深海底生存的最大问题
Funnily enough, the biggest problem for survival at extreme depths
与在极高海拔处生存类似 至少对哺乳动物来说是如此
is the same as at extreme heights, at least for mammals
你会开始觉得氧气不足
You start running low on oxygen
人类不携带氧气设备潜水的最深记录
The deepest a human has ever dived without taking oxygen with them
是大约250米
is about 250 meters
不过这和其他哺乳动物相比就不值一提了
but that’s nothing compared to some other mammals
南象海豹可以潜入2400米深处
Southern elephant seals can dive more than 2400 meters
在2014年科考人员观察到
and in 2014, scientists watched as
一只居维耶岛突吻鲸潜入了海平面以下3000米
a Cuvier’s beaked whale dove 3000 meters below the surface
因为哺乳动物需要呼吸
Since mammals have to breath air
所以潜入深海时需要特殊性适应
they need special adaptations to dive that far
比如某些物种有很多红细胞
For example, some species have more red blood cells
因此可以降低心率
can slow down their heart rate
或者暂时让非必要器官停止工作 例如肾脏
or can temporarily shut down non-vital organs like their kidneys
一些物种具有更多肌红蛋白 可以把氧气储存在肌细胞中
Some also have extra myoglobin, a protein that stores oxygen in muscle cells
但这些潜入深海的动物只是过客 不会停留过久
But these divers are just visitors
而有些物种一生都生活在深海
There are species of animals that spend their entire lives in the deep ocean
2017年 科学家发现了已知位于最深海底的脊椎动物
In 2017, scientists found the deepest known vertebrate
一种粉红色蠕动前行的狮子鱼
a pink, wiggly snailfish
位于马里亚纳海沟8000米深处
at over 8,000 meters down in the Mariana Trench
是该海域最深的地方
the deepest part of the ocean
与鲸和海豹不同 这种鱼不存在难以获取氧气的问题
The fish doesn’t have that oxygen problem that whales and seals do
因为它直接从水中获取氧气
since it gets its oxygen directly from the water
但是还有一个问题:水压
But there is another problem: pressure
水的比重很大
Water is heavy
随着潜入深度增加 水压也随之变大
and the deeper you go in the ocean, the stronger the water pressure becomes
8000米深的水压好比身体上每平方厘米都坐着一头牛
At 8,000 meters, the pressure is like having a cow sitting on every square centimeter of your body
而且这头牛块头不小
And not a small cow either
在此深处水压如此之强
At that point, the pressure is so great
甚至可能会破坏组成鱼身的蛋白质
it might actually destabilize the proteins the fish’s body is made of
简而言之 生物学家认为这种鱼的组织富含一种化合物
To compensate, biologists think the fish’s tissues are full of a compound
叫做氧化三甲胺 简称TMAO
called trimethylamine N-oxide, or TMAO for short
可以使蛋白质保持稳定
which can help stabilize proteins
TAMO在鱼类中很常见
TMAO is common in fish
越深的水底鱼类含有的TMAO越多
and the deeper you go, the more of it they tend to have
不过即使存在这个适应特性
But even with this adaptation
这种鱼也是已知的生活在最深海底的鱼类
this may be the deepest fish we’re ever going to see
科学家们推测 当海深超过8200米时
Researchers have calculated that beyond 8200 meters
鱼类需要大量TAMO来抵抗水压
fish would need so much TMAO to withstand the pressure
以至于细胞的含盐量比周围海水更大
that their cells would be saltier than the seawater around them
那时更多的水会通过渗透作用进入细胞
Except then more water would rush into the cells through osmosis
细胞因此会胀
and then they would explode
所以你现在能明白TMAO太多也是个问题了吧
and you can see why that would be a problem
然而 我们还可以到达更深的海底
And yet, we can go even deeper
2012年詹姆斯·卡梅隆
In 2012, James Cameron
导演了《阿凡达》和《泰坦尼克号》的那个人
yeah, the guy who made Avatar and Titanic
乘坐一艘潜水艇潜入马里亚纳海沟最深处
visited the deepest part of the Mariana Trench in a submersible
即使在海平面以下10000米深的地方
And even there, over 10,000 meters below the surface
他也见到了相当复杂的生命体
he was greeted by relatively complex life
一英尺长的巨型甲壳纲动物 也叫海沟巨虾
giant, foot-long crustaceans, known as amphipods
海参 还有形状奇特 黏黏糊糊 带壳的有孔虫
sea cucumbers, and weird, gooey, shelled things called foraminifera
我们仍不了解
There’s a lot we still don’t know about
这些生活在这片海域最深处的生物
the organisms that live in the deepest parts of the ocean
这里是地球上最大的栖息地之一
It’s one of the biggest habitats on Earth
也是最难进行科学考察的地方
and yet it’s also the hardest to explore
但是我们确信 这里的生命更具适应性
But we do know that life is super adaptable
拥有这些惊奇的适应特性
And with a collection of those amazing adaptations
复杂生命体就可以生存在最高的山峰和最深的海底
complex life can exist at some incredible highs and some very low lows
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as well as other topics like history and technology
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即使在死亡谷
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[片尾]
[♩OUTRO]

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极端环境中的复杂生命

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视频来源

https://www.youtube.com/watch?v=-_BZovJrnHM

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