PART 4

For my project on invertebrates, I chose to study tardigrades.

在我的无脊椎动物项目中，我选择了研究缓足虫。

These are microscopic – or to be more precise – near-microscopic animals.

这种动物是微生物，或者更准确地说是近微生物。

There are well over a thousand known species of these tiny animals, which belong to the phylum Tardigrada.

这种微小的动物有一千多个已知物种，属于缓步动物门。

Most tardigrades range in length from 0.05 to 1 millimetre, though the largest species can grow to be 1.2 millimetres in length.

大多数蜥脚类动物的长度在 0.05 到 1 毫米之间，不过最大的种类可以长到 1.2 毫米。

They are also sometimes called 'water bears' : 'water' because that's where they thrive best, and 'bear' because of the way they move.

它们有时也被称为 "水熊"："水 "是因为它们在水里生长得最好，而 "熊 "则是因为它们移动的方式很像。

'Moss piglet' is another name for tardigrades because of the way they look when viewed from the front.

“苔藓小猪”是缓足虫的另一个名字，因为从正面看它们的样子很像。

They were first discovered in Germany in 1773 by Johann Goeze, who coined the name Tardigrada.

它们最早于1773年在德国被约翰 · 戈泽发现，他创造了“缓步动物”这个名字。

As I say, there are many different species of tardigrade – too many to describe here – but, generally speaking, the different species share similar physical traits.

正如我所说，缓足虫有许多不同的种类——太多了，这里无法一一描述——但是，一般来说，不同的物种有着相似的生理特征。

They have a body which is short, and also rounded – a bit like a barrel – and the body comprises four segments.

它们有一个短而圆的身体——有点像桶——身体由四个部分组成。

Each segment has a pair of legs, at the end of which are between four and eight sharp claws.

每一节都有一对腿，末端有四到八只锋利的爪子。

I should also say that some species don't have any claws; what they have are discs, and these work by means of suction.

另外，一些物种没有爪子；它们有的只是圆盘，这些圆盘通过吸力工作。

They enable the tardigrade to cling on to surfaces or to grip its prey.

它们使缓足虫能够附着在表面或者抓住猎物。

Within the body, there are no lungs, or any organs for breathing at all. Instead, oxygen and also blood are transported in a fluid that fills the cavity of the body.

在它的体内，没有肺，也没有任何用于呼吸的器官。相反，氧气和血液在充满体腔的液体中运输。

As far as the tardigrade's head is concerned, the best way I can describe this is that it looks rather strange – a bit squashed even – though many of the websites I looked at described its appearance as cute, which isn't exactly very scientific.

就缓足虫的头而言，我能描述的最好的方式就是它看起来很奇怪——甚至有点被压扁了——尽管我看过的许多网站描述它的外观很可爱，这并不是很科学。

The tardigrade's mouth is a kind of tube that can open outwards to reveal teeth-like structures known as 'stylets'.

缓足动物的嘴是一种管状物，可以向外张开，露出被称为“口针”的牙齿状结构。

These are sharp enough to pierce plant or animal cells.

这些结构非常锋利，足以刺穿植物或动物细胞。

So, where are tardigrades found?

那么，缓足虫是在哪里被发现的呢？

Well, they live in every part of the world, in a variety of habitats: most commonly, on the bed of a lake, or on many kinds of plants or in very wet environments.

嗯，它们生活在世界的每一个角落，栖息地多种多样: 最常见的是，在湖床上、多种植物上或在非常潮湿的环境中。

There's been some interesting research which has found that tardigrades are capable of surviving radiation and very high pressure, and they're also able to withstand temperatures as cold as–200 degrees centigrade, or highs of more than 148 degrees centigrade, which is incredibly hot.

有一些有趣的研究发现缓足虫能够在辐射和高压下生存，而且它们还能够承受零下200摄氏度的低温，或者超过148摄氏度的高温，这是难以忍受的高温。

It has been said that tardigrades could survive long after human beings have been wiped out, even in the event of an asteroid hitting the earth.

据说缓足虫可以在人类灭绝之后存活很长时间，即使是在小行星撞击地球的情况下。

If conditions become too extreme and tardigrades are at risk of drying out, they enter a state called cryptobiosis.

如果环境变得过于极端，缓足虫面临干涸的危险，它们就会进入隐生状态。

They curl into a ball, called a tun – that's T-U-N – by retracting their head and legs, and their metabolism drops to less than one percent of normal levels.

它们把头和腿缩成一团，称为 "桶"（Tun），新陈代谢下降到正常水平的百分之一以下。

They can remain like this until they are reintroduced to water, when they will come back to life in a matter of a few hours.

它们可以保持这种状态，直到重新接触到水，几小时后，它们就会恢复生机。

While in a state of cryptobiosis, tardigrades produce a protein that protects their DNA.

当处于隐生状态时，缓足虫产生一种蛋白质来保护它们的DNA。

In 2016, scientists revived two tardigrades that had been tuns for more than 30 years. 2016

年，科学家们复活了两种已经存在了30多年的缓足虫。

There was a report that, in 1948, a 120-year-old tun was revived, but this experiment has never been repeated.

有报道说，在1948年，一只120岁的缓足虫复活了，但是这个实验从来没有被重复过。

There are currently several tests taking place in space, to determine how long tardigrades might be able to survive there.

目前有几项测试正在太空中进行，以确定缓足虫能在那里生存多久。

I believe the record so far is 10 days.

到目前为止的记录是10天。

So, erm, moving on. In terms of their diet, tardigrades consume liquids in order to survive.

所以，继续，从它们的饮食来看缓足虫为了生存会摄入液体。

Although they have teeth, they don't use these for chewing.

虽然它们有牙齿，但它们不用这些来咀嚼。

They suck the juices from moss, or extract fluid from seaweed, but some species prey on other tardigrades, from other species or within their own.

它们从苔藓中吸取汁液，或者从海藻中提取液体，但是一些物种会捕食其他的缓足虫，从其他物种或在它们自己的物种中摄入汁液。

I suppose this isn't surprising, given that tardigrades are mainly comprised of liquid and are coated with a type of gel.

我想这并不奇怪，因为缓足虫主要是由液体组成，并且被一种凝胶包裹着。

Finally, I'd like to mention the conservation status of tardigrades.

最后，我想提一下缓足虫的保护现状。

It is estimated that they have been in existence for approximately half a billion years and, in that time, they have survived five mass extinctions.

据估计，它们已经存在了大约5亿年，在此期间，它们经历了5次大灭绝。

So, it will probably come as no surprise to you, that tardigrades have not been evaluated by the International Union for Conservation of Nature and are not on any endangered list.

因此，你可能不会感到惊讶，缓步动物没有被国际自然保护联盟评估过，也没有被列入任何濒危物种名单。

Some researchers have described them as thriving.

一些研究人员称它们正在茁壮成长。

Does anyone have any questions they'd like to ask?

大家有什么问题想问吗？