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

但有一種如此強韌的生物，沒水也能存活幾十年

This one millimeter animal can survive both the hottest

這個一毫米長的動物，能夠存活於

and coldest environments on Earth,

地球上最熱和最冷的環境

and can even withstand high levels of radiation.

甚至可以承受高強度的放射線

This is the tardigrade,

見見緩步動物

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

世界上最強悍的其中一種動物

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

雖然牠看起來比較像一隻肥嘟嘟的八腳小熊軟糖

Most organisms need water to survive.

絕多數生物需要水才能存活

Water allows metabolism to occur,

水讓新陳代謝得以維持

which is the process that drives all the biochemical reactions

才能驅使細胞中的生物化學反應

that take place in cells.

開始作用

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

但像緩步動物，或熟知為水熊蟲的這種生物

get around this restriction with a process called anhydrobiosis,

能夠藉由一種稱為脫水生活 (anhydrobiosis) 的過程不受規則束縛

from the Greek meaning life without water.

anhydrobiosis 源自希臘文，意思是無水的生活

And however extraordinary, tardigrades aren't alone.

雖然很特殊，但緩步動物門並非個案

Bacteria,

細菌、

single-celled organisms called archaea,

單細胞生物古菌、

plants,

植物

and even other animals can all survive drying up.

甚至其他動物，都能撐過乾巴巴的環境

For many tardigrades,

對於許多緩步動物來說

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

這意味著要進入一個叫做大桶狀態的過程

They curl up into a ball,

他們踡縮成一顆球

pulling their head and eight legs inside their body

把他們的頭和八隻腿收進身體裡

and wait until water returns.

等待水再次到來

It's thought that as water becomes scarce

認知是當水源不足

and tardigrades enter their tun state,

緩步動物進入大桶狀態時

they start synthesize special molecules,

他們開始合成特殊的分子

which fill the tardigrade's cells to replace lost water

這些分子藉由組成基質，填滿緩步動物的細胞

by forming a matrix.

代替流失的水分

Components of the cells that are sensitive to dryness,

細胞中對乾燥敏感的組成物

like DNA,

如 DNA、

proteins,

蛋白質、

and membranes,

和細胞膜

get trapped in this matrix.

都被鎖在基質裡

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

人們認為這能夠讓分子維持狀態

to stop them from unfolding,

以免他們散開、

breaking apart,

分崩離析、

or fusing together.

或融合在一起

Once the organism is rehydrated, the matrix dissolves,

一旦有機體逢遇甘霖，基質就會溶解

leaving behind undamaged, functional cells.

留下完好無損、功能完善的細胞

Beyond dryness, tardigrades can also tolerate other extreme stresses:

不只是乾燥環境，緩步動物也能忍受其他極端壓力：

being frozen,

被冰凍、

heated up past the boiling point of water,

在超過沸點的沸水中加熱、

high levels of radiation,

高強度的放射線

and even the vacuum of outer space.

甚至是外太空真空狀態

This has led to some erroneous speculation

這因此引發一些錯誤的猜測

that tardigrades are extraterrestrial beings.

以為緩步動物是外星物種

While that's fun to think about,

這樣想頗好笑的

scientific evidence places their origin firmly on Earth

因為科學證據確立了他們源自地球

where they've evolved over time.

並且經過了時間演化

In fact, this earthly evolution has given rise

事實上，緩步動物在地球上的演化

to over 1100 known species of tardigrades

至今已有超過 1100 種已知品種

and there are probably many others yet to be discovered.

並且或許還有許多尚未被發現的品種

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

正因為緩步動物如此硬派，幾乎到處都看得到他們的蹤影

They live on every continent, including Antarctica.

他們遍及各大洲，包括南極洲

And they're in diverse biomes including deserts,

而且他們存在在多元的生物群系，包含沙漠、

ice sheets,

冰原、

the sea,

海洋、

fresh water,

淡水、

rainforests,

雨林、

and the highest mountain peaks.

和山脈頂峰

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

但你也能在最尋常的地方找到緩步動物

like moss or lichen found in yards,

比如庭院裡的苔蘚和青苔

parks,

以及公園

and forests.

和森林裡的

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

要找到他們，你只需要一些耐心和一台顯微鏡

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

現在科學家還在試著探究緩步動物是否還會利用他們的大桶狀態

their anti-drying technique,

也就是抗乾燥技術

to survive other stresses.

來抵禦其他生存壓力

If we can understand how they, and other creatures,

如果我們能夠了解他們和其他生物

stabilize their sensitive biological molecules,

是如何穩固他們敏感的生理分子

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

或許我們也能將這項技術應用到穩固疫苗

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

或是研發出能夠適應地球氣候變遷的抗壓作物

And by studying how tardigrades survive

藉由研究緩步動物

prolonged exposure to the vacuum of outer space,

如何活過長時間的外太空真空狀態

scientists can generate clues about the environmental limits of life

科學家能夠歸究出環境限制生命的線索

and how to safeguard astronauts.

還有如何保護外太空人

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

在此同時，緩步動物或許甚至能幫助我們回答這個重大問題：

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

生物是否可以在生存環境劣於地球的星球生存？