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

翻译人员: Riley WANG 校对人员: Amy H. Fann

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

如果没有水，人类只能存活一百小时左右。

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

但是有一种适应力极强的生物 可以生存几十年没有水。

This one millimeter animal can survive both the hottest

这种长仅一毫米的动物可以在地球上

and coldest environments on Earth,

最热以及最冷的环境下生存，

and can even withstand high levels of radiation.

甚至能够承受高剂量的辐射。

This is the tardigrade,

这就是缓步动物，

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

它是地球上生命力最强的生物之一，

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

即使它看着更像是 一个胖胖的八脚小熊。

Most organisms need water to survive.

大部分的有机体依靠水来生存。

Water allows metabolism to occur,

水使得新陈代谢得以进行，

which is the process that drives all the biochemical reactions

而新陈代谢则驱动着一切细胞中的

that take place in cells.

生化反应。

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

但是缓步动物，也称水熊虫，

get around this restriction with a process called anhydrobiosis,

可以通过低湿隐生， 即在没有水的情况下生存，

from the Greek meaning life without water.

从而避免新陈代谢需要水这一限制。

And however extraordinary, tardigrades aren't alone.

而并不只有水熊虫 拥有这项超凡的本领。

Bacteria,

细菌，

single-celled organisms called archaea,

被称为古细菌的单细胞生物，

plants,

植物，

and even other animals can all survive drying up.

甚至其他动物都可以脱水生活。

For many tardigrades,

对于很多水熊虫来说，

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

脱水需要经历“小桶状态”。

They curl up into a ball,

它们卷曲成一个小球，

pulling their head and eight legs inside their body

使自己的头和八只脚缩进身体里，

and wait until water returns.

以这种状态等待水的到来。

It's thought that as water becomes scarce

一般认为，当环境中的水变得稀缺时，

and tardigrades enter their tun state,

水熊虫即进入“小桶状态”，

they start synthesize special molecules,

它们开始合成特殊的分子，

which fill the tardigrade's cells to replace lost water

这种分子可以形成一种基体 充满水熊虫的细胞，

by forming a matrix.

从而代替失去的水。

Components of the cells that are sensitive to dryness,

那些对干燥比较敏感的细胞组成部分，

like DNA,

如DNA，

proteins,

蛋白质，

and membranes,

细胞膜，

get trapped in this matrix.

都会被固定在基体中。

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

普遍认为，这可以使 这些分子保持在原位，

to stop them from unfolding,

从而使它们不会展开，

breaking apart,

碎裂，

or fusing together.

或是混合在一起。

Once the organism is rehydrated, the matrix dissolves,

一旦有机体获得水，基体就会溶解，

leaving behind undamaged, functional cells.

而细胞不会受到损害，功能完好。

Beyond dryness, tardigrades can also tolerate other extreme stresses:

除了干旱，水熊虫还可以 忍受其他极端条件：

being frozen,

冷冻，

heated up past the boiling point of water,

沸水加热，

high levels of radiation,

高强度辐射，

and even the vacuum of outer space.

甚至是外太空的真空环境。

This has led to some erroneous speculation

这引发了一些错误的推测，

that tardigrades are extraterrestrial beings.

例如水熊虫是外星生物。

While that's fun to think about,

虽然这听上去很有趣，

scientific evidence places their origin firmly on Earth

但是科学证实它们确实起源于地球，

where they've evolved over time.

并且在地球上进化。

In fact, this earthly evolution has given rise

事实上，在地球上的这一进化过程

to over 1100 known species of tardigrades

演化出了1100种以上水熊虫，

and there are probably many others yet to be discovered.

但是很可能还有众多 其他种类尚待发现。

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

由于缓步动物如此坚强， 它们能够存在于任何地方。

They live on every continent, including Antarctica.

包括南极洲在内的五大洲都有它们的身影。

And they're in diverse biomes including deserts,

在各种各样的生物群落中， 包括沙漠，

ice sheets,

冰川，

the sea,

海洋，

fresh water,

淡水，

rainforests,

雨林，

and the highest mountain peaks.

以及世界最高峰。

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

你也可以在最普通的地方找到它们，

like moss or lichen found in yards,

比如在花园、

parks,

公园、

and forests.

森林中的苔藓或地衣。

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

你只需要一些耐心和 一个放大镜就能找到它们。

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

科学家们现在正在努力弄清一件事：

their anti-drying technique,

水熊虫是否能够通过“小桶状态”和反干旱技能

to survive other stresses.

在其他严酷条件下生存。

If we can understand how they, and other creatures,

如果我们能明白它们和其他生物

stabilize their sensitive biological molecules,

如何使敏感的生物分子 保持稳定状态，

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

我们也许就可以将其用于稳定疫苗

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

或者是发展能够 应对全球气候变化的农作物。

And by studying how tardigrades survive

通过研究水熊虫如何在

prolonged exposure to the vacuum of outer space,

外太空的真空环境下延长存活时间，

scientists can generate clues about the environmental limits of life

科学家可以找出生命在环境中的极限

and how to safeguard astronauts.

以及如何保护宇航员。

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

在研究中，水熊虫甚至可以 帮我们回答一个重要问题：

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

生命是否能够在 比地球环境更恶劣的星球上存活？