好英语网地球上生命力最强的动物：水熊虫、南极雪人蟹、雪山斑头雁、沙漠骆驼
If you’re looking to the animal kingdom for tough customers, you need look no further than tardigrades. These eight-legged animals can survive extremes of heat, cold – even the vacuum of space. Wherever they are found – the Himalayas, ocean abysses, volcanic mud or chilling in Antarctica – the remarkable resilience of tardigrades is due to their ability to survive without water. Under extreme stress, the animals enter a state known as ‘cryptobiosis’, dehydrating themselves and protecting their cells with special proteins and sugars. The aquatic species are revived by water, which combined with their podgy appearance has earned them the nickname ‘water bears’.
如果你正在寻找动物界生命力最坚强的家伙，看过水熊虫之后，相信就有一个答案了。水熊虫有八条腿，在酷热、严寒，甚至是真空的环境下，也能够生存。无论是在喜马拉雅山脉、海洋深处、火山泥里或是极寒的南极洲，都能找到水熊虫的踪迹。这种动物有着惊人的生存韧性，这得益于它们能够在无水状况下的生存能力。处于极度的压力下，水熊虫会进入“隐生”状态，自身脱水、同时生产出特殊的蛋白质和糖质保护自身细胞。这种水生物种遇水就会重新活过来，又由于其外观笨拙，于是有了“水熊”的绰号。
But before you rename your sports team in honour of these critters, it’s worth mentioning they measure less than 1mm long. If you’re looking for more than a ‘tiny but mighty’ reputation, read on for a round-up of some of the other species showing their mettle in extreme circumstances.
但如果你要用水熊的名头给自己的运动队起名，那还需要注意一点：水熊虫的长度甚至不到1毫米。如果你要的不只是“个头小，力量大”的话，，那接下来介绍的其他物种也在恶劣的条件下展现出顽强生命力。
Toughened to temperatures
耐抗极端温度
The coldest water in the world is found below Antarctic ice shelves while elsewhere in the Southern Ocean boiling water spews up from cracks in the seabed. In such a contrary environment you’d expect some oddities but even the wildest imagination is unlikely to come up with the yeti crabs (Kiwa S.).
世界上最冷的水域位于南极冰架下方，但南极海域也有一些地方，海底的裂缝中会有沸水喷涌而出。在这样的一个极端反差的环境下，人们期望有一些古怪的事情发生，这无可厚非。但是，南极雪人蟹的存在绝对超出了人们想象力。
《蓝色星球II：前传》（Blue Planet II Prequel）中展示的南极雪人蟹
Named for the abominable appearance of their long hairy arms, these blind crustaceans are adapted to endure crushing pressure and no sunlight at depths of up to 2,300 ft (700m) below sea level. Their survival is dependent on the hydrothermal vents they live near, where water as hot as 400C boils up from beneath the Earth’s surface, bringing mineral deposits with it. Bacteria thrive around the vents, converting the minerals to energy. In turn, the crabs are sustained by the bacteria, but it’s a delicate balance to stay in the sweet spot between the boiling vent water and lethally cold ocean.
雪人蟹的四肢长满白毛，状似雪人因而得名。这种甲壳类动物，生活在海平面以下2300英尺（700米）不见天日的海底，它们没有视力，而且能抵抗海底的高压。雪人蟹的生存与栖息地附近的深海热液喷口息息相关。热液喷口处的温度可达400摄氏度，由地心热能加热后，水会连带着矿物沉积一同喷出。深海热液喷口附近会长有许多细菌，它们能够把矿物质转化为能量。雪人蟹则以细菌为生，它们必须在沸腾出水口和刺骨的海水之间维持一个微妙的平衡。
Featured in Blue Planet II, scientists observed the species informally known as ‘Hoff crabs (Kiwa tyleri) (thanks to their hairy chests resembling that of Baywatch star David Hasselhof) fighting for position around the chimney-like structures created where the fiercely hot water deposits minerals from beneath the Earth’s surface.
纪录片《蓝色星球II》中，科学家们注意到了这个物种，并非正式地称之为“霍夫螃蟹”（Hoff crabs），因为它们毛茸茸的蟹盖像极了《护滩使者》（Baywatch）里的明星哈塞尔霍夫（David Hasselhof）毛茸茸的胸口。深海热液喷口酷似烟囱，沸腾的热水会从地心喷出，并带出沉积的矿物质。科学家们观察到，霍夫螃蟹会争夺热液喷口处的领地。
Living the high life
高海拔区的适应强者
From the seabed to mountain tops, you’d imagine there would be a very different set of challenges to overcome. But temperature is just asig a factor at altitude, where mountain peaks can be cold enough for exposed flesh to freeze. That’s why yaks (Bos mutus) sport such thick hides; a double thickness of woolly undercoat beneath their long hair helps to keep essential areas such as the chest insulated. Even with their impressive outerwear, yaks cannot survive beyond around 18,000 ft (5,500m) because the higher you go, the thinner the air becomes.
不难想象，从海底到山顶的生存条件不同，要克服的困难也大不一样。气温随着海拔高度发生改变，山顶的温度最低，甚至能够把暴露在外的皮肤冻住。牦牛之所以能在此生存，归功于其厚实的皮毛；在它们的长毛之下，还有一层加厚的绒短毛，隔绝了胸腔等重要部位，使之不会暴露在空气中。但即便有这样的好“外衣”，牦牛也无法在海拔18000英尺（5500米）以上的环境生存。这是因为越往上走，空气就越稀薄。
Low air pressure means less oxygen, so species at extreme altitude need physiological advantages to help them make the most of what’s available. Big lungs, specialised muscles and an abundance of blood vessels that transport oxygen to essential tissues are the secrets of success for arguably our highest-flying species: the bar headed goose (Anser indicus).
气压越低，氧气就越少。也就是说，在海拔极高的环境中生存，生物需要发展出生理优势，尽可能适应环境。斑头雁也许是地球上能飞得最高的动物，这归功于他们巨大的肺、特别的运动肌肉，以及足够的血管，能够将氧气传输到必要的器官组织中去。
Birds are known for some extraordinary feats during their migrations, foremost among them are the geese that cross the Himalayas annually. The birds have been recorded cresting Mount Everest at 30,000ft high, though they usually take a slightly ‘easier’ route through mountain passes that would still leave human mountaineers literally breathless.
鸟类迁徙过程中，有一些壮举着实出名。最负盛名的要数这种大雁，每年都会穿越喜马拉雅山脉。有记录显示，这种鸟类曾经登顶30000英尺（约9000米）高的珠穆朗玛峰，它们的路线略微“容易”一些，但对于人类来说，走那条线路绝对会让人窒息。
斑头雁是飞得最高的物种
What’s truly extraordinary is that the birds can climb between 4,000 and 6,000 m in just 7-8 hours thanks to their adaptations, and scientists suggest they undertake this athletic feat without any prior training.
生物进化适应，斑头雁能够在短短7-8小时内飞升至4000至6000米的高空，着实非凡。科学家说，斑头雁的这一能力并非是后天训练所致。
Drying times
干涸之地的生存专家
We know that water is an essential element for most of life on Earth, so species that survive in the world’s most arid environments really have their work cut out for them. Of all the desert animals, the camel is easily the most iconic. Whether they have one hump (Camelus dromedarius) or two (C. bactrianus), they can take on temperatures of over 40C and endure water losses greater than 25% of their total body weight.
我们知道，水是地球上大部分生命的必需元素。要在地球上最干旱的环境中生存，动物必须做好充分的准备。显然，骆驼是所有沙漠动物中最具有代表性的。无论是单峰骆驼还是双峰骆驼，都能够在40摄氏度以上的温度生存，而且在身体水分流失量达到总体重25%的情况下，还能维持生命。
骆驼是标志性的生存专家
To set the record straight, camel humps are not used for water storage – they are fatty deposits. While fat can be metabolised into water, animals in dry conditions lose too much moisture through respiration trying to get enough oxygen for the process to make it worthwhile. Instead, the fats can be used for nutrition when food is scarce. They also protect camels from the sun as the fatty tissue is slow to conduct heat and by locating most of their body fat on their back the animals carry less insulation elsewhere, helping to keep them cool. So, think of the humps as heat-shielding picnic parasols rather than flasks.
必须要澄清一点，骆驼的驼峰并不能用来储水——驼峰只是脂肪堆积而成的。虽然脂肪燃烧时会产生水，但在干燥环境下，动物会控制呼吸频率，只保证（维持生命所需的）最低脂肪消耗，因此呼吸带走的水分会更少。食物稀缺时，脂肪可用于营养供给。驼峰还可以帮助骆驼免受光照伤害，这是因为脂肪组织的导热速度慢，当身体大部分脂肪都囤积在背部时，其他部位的隔热脂肪较少，这也能保证他们更加凉快。因此，我们应该将驼峰视为野餐时的隔热遮阳伞，而不是背上的储水瓶。
While their humps are hard to ignore, some of camels’ best features are internal. Scientists investigating the evolutionary background of camels have identified key physiological mechanisms that represent adaptations to the desert environment.
虽然驼峰很明显，但骆驼某些适应环境的特征来自于它们身体内部。在研究了骆驼的进化后，科学家已经确认了其适应沙漠环境而进化出的关键生理机制。
Due to highly efficient kidneys and intestines, camels lose very little water through waste. They pee very sporadically; their urine is super-concentrated, and their droppings are exceptionally dry. Their red blood cells are also specially adapted to cope with fluctuating hydration: they can expand to 240% of their initial volume, whereas other species’ will burst beyond 150%. Camels’ red blood cells are also smaller and oval shaped, meaning they can flow more easily even when the blood is thickened through extreme dehydration.
骆驼的肾脏和肠道运作效率很高，因此排泄时仅会损失很少的水分。骆驼很少排尿；尿液浓度很高，粪便特别干燥。它们的红细胞也经历了进化，以应对时多时少的水合作用：骆驼的红细胞可以扩展到初始体积的240％，其他物种的红细胞体积扩张到150％后就会爆炸。骆驼的红细胞较小且呈椭圆形，这意味着即使血液因极度脱水而变稠，红细胞也可以更容易地流动。
For our most indefatigable species then, the secrets of survival in hostile conditions are literally in the blood.
这种最不知疲倦的物种，其在极端条件下生存的秘密，其实就藏在他们的“血液”里。