Meet the tardigrade, the toughest animal on Earth - Thomas Boothby

譯者: Yueh-Lun Huang 審譯者: Helen Chang

Without water, a human can only survive for about 100 hours.

沒有水，人類只能存活約一百小時

But there's a creature so resilient that it can go without it for decades.

但有一種韌性的生物 可以數十年不喝水

This one millimeter animal can survive both the hottest

這種一毫米的動物可以生存在

地球上最炎熱和最寒冷的環境

and coldest environments on Earth,

and can even withstand high levels of radiation.

甚至承受高強度輻射

This is the tardigrade,

它是「緩步動物」

and it's one of the toughest creatures on Earth,

地球上最強韌的生物之一

even if it does look more like a chubby, eight-legged gummy bear.

即使他看起來像是圓胖的八腳軟糖熊

Most organisms need water to survive.

大多數的有機體都需要水才能生存

Water allows metabolism to occur,

水使新陳代謝得以進行

which is the process that drives all the biochemical reactions

那是發生在所有生物細胞中的 化學反應過程

that take place in cells.

But creatures like the tardigrade, also known as the water bear,

但是別名「水熊蟲」的緩步動物 和其他類似的生物

get around this restriction with a process called anhydrobiosis,

可通過「低濕隱生」的過程而不受限

from the Greek meaning life without water.

在希臘語的意思是「無水生活」

And however extraordinary, tardigrades aren't alone.

然而不只緩步動物有這非凡的特性

Bacteria,

細菌

single-celled organisms called archaea,

稱作「古菌」的單細胞生物

plants,

植物

and even other animals can all survive drying up.

甚至其他動物都可以缺水生存

For many tardigrades,

許多緩步動物必須經過 一種所謂的「小桶狀態」

this requires that they go through something called a tun state.

They curl up into a ball,

牠們會蜷縮成球狀

pulling their head and eight legs inside their body

把自己的頭和八隻腳縮進身體

and wait until water returns.

等待水分回來

普遍認為缺乏水分時

It's thought that as water becomes scarce

and tardigrades enter their tun state,

緩步動物就會進入小桶狀態

they start synthesize special molecules,

開始合成特殊的分子來填補細胞

which fill the tardigrade's cells to replace lost water

形成基質以取代失去的水分

by forming a matrix.

Components of the cells that are sensitive to dryness,

把那些對乾燥敏感的細胞成分

like DNA,

如 DNA

proteins,

蛋白質

and membranes,

和細胞膜

get trapped in this matrix.

固定在基質裡

It's thought that this keeps these molecules locked in position

一般認為這使得分子鎖定在原位

to stop them from unfolding,

防止它們擴張

breaking apart,

分裂

or fusing together.

或融合在一起

Once the organism is rehydrated, the matrix dissolves,

一旦有機體重新遇水

基質就會溶解

leaving behind undamaged, functional cells.

留下未損壞且功能完好的細胞

Beyond dryness, tardigrades can also tolerate other extreme stresses:

除了乾燥

緩步動物也能容忍其他極端的壓力

being frozen,

凍結

heated up past the boiling point of water,

加熱至沸點的水

high levels of radiation,

高強度輻射

and even the vacuum of outer space.

甚至是外太空的真空環境

This has led to some erroneous speculation

這也導致了一些錯誤的猜測

that tardigrades are extraterrestrial beings.

緩步動物是外星生物

While that's fun to think about,

雖然想起來很有意思

scientific evidence places their origin firmly on Earth

但科學證據顯示牠們確實起源於地球

where they've evolved over time.

並且在地球上與時進化

In fact, this earthly evolution has given rise

事實上，於地球的演化已經發展出

to over 1100 known species of tardigrades

超過 1100 種的已知緩步動物

and there are probably many others yet to be discovered.

很可能還有許多種尚未被發現

And because tardigrades are so hardy, they exist just about everywhere.

因為緩步動物如此地強韌

到處都有牠們

They live on every continent, including Antarctica.

牠們居住在每個大陸，包括南極洲

And they're in diverse biomes including deserts,

活在各種的生物群落中，包括沙漠

ice sheets,

冰蓋

the sea,

海洋

fresh water,

淡水

rainforests,

雨林

and the highest mountain peaks.

和最高的山峰

But you can find tardigrades in the most ordinary places, too,

但你也能在普通的地方找到緩步動物

like moss or lichen found in yards,

像在苔蘚或地衣裡

parks,

院子、公園和森林裡就有

and forests.

All you need to find them is a little patience and a microscope.

你只需要一點耐心和顯微鏡 就找得到牠們

Scientists are now to trying to find out whether tardigrades use the tun state,

科學家們正努力釐清

緩步動物是否能透過小桶狀態

their anti-drying technique,

以及抗乾燥技術

to survive other stresses.

在其他壓力下存活

If we can understand how they, and other creatures,

如果我們能理解牠們和其他的生物

stabilize their sensitive biological molecules,

如何穩定住敏感的生物分子

perhaps we could apply this knowledge to help us stabilize vaccines,

也許我們能應用這些知識來穩定疫苗

or to develop stress-tolerant crops that can cope with Earth's changing climate.

或發展出抗逆境作物來對抗氣候變遷

And by studying how tardigrades survive

同時，研究緩步動物是如何生存於

prolonged exposure to the vacuum of outer space,

長時間暴露在外太空的真空空間

scientists can generate clues about the environmental limits of life

科學家可以找出生命受環境限制的線索

and how to safeguard astronauts.

以及如何保護太空人

In the process, tardigrades could even help us answer a critical question:

過程中，緩步動物甚至能 幫我們回答一個關鍵問題：

could life survive on planets much less hospitable than our own?

生命是否能在比地球環境 更惡劣的行星上存活？