干涸之地的生存專家

干涸之地的生存專家

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.

我們知道，水是地球上大部分生命的必需元素。要在地球上最干旱的環(huán)境中生存，動(dòng)物必須做好充分的準(zhǔn)備。顯然，駱駝是所有沙漠動(dòng)物中最具有代表性的。無(wú)論是單峰駱駝還是雙峰駱駝，都能夠在40攝氏度以上的溫度生存，而且在身體水分流失量達(dá)到總體重25%的情況下，還能維持生命。

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.

必須要澄清一點(diǎn)，駱駝的駝峰并不能用來(lái)儲(chǔ)水——駝峰只是脂肪堆積而成的。雖然脂肪燃燒時(shí)會(huì)產(chǎn)生水，但在干燥環(huán)境下，動(dòng)物會(huì)控制呼吸頻率，只保證(維持生命所需的)最低脂肪消耗，因此呼吸帶走的水分會(huì)更少。食物稀缺時(shí)，脂肪可用于營(yíng)養(yǎng)供給。駝峰還可以幫助駱駝免受光照傷害，這是因?yàn)橹窘M織的導(dǎo)熱速度慢，當(dāng)身體大部分脂肪都囤積在背部時(shí)，其他部位的隔熱脂肪較少，這也能保證他們更加涼快。因此，我們應(yīng)該將駝峰視為野餐時(shí)的隔熱遮陽(yáng)傘，而不是背上的儲(chǔ)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.

雖然駝峰很明顯，但駱駝某些適應(yīng)環(huán)境的特征來(lái)自于它們身體內(nèi)部。在研究了駱駝的進(jìn)化后，科學(xué)家已經(jīng)確認(rèn)了其適應(yīng)沙漠環(huán)境而進(jìn)化出的關(guān)鍵生理機(jī)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.

駱駝的腎臟和腸道運(yùn)作效率很高，因此排泄時(shí)僅會(huì)損失很少的水分。駱駝很少排尿;尿液濃度很高，糞便特別干燥。它們的紅細(xì)胞也經(jīng)歷了進(jìn)化，以應(yīng)對(duì)時(shí)多時(shí)少的水合作用：駱駝的紅細(xì)胞可以擴(kuò)展到初始體積的240%，其他物種的紅細(xì)胞體積擴(kuò)張到150%后就會(huì)爆炸。駱駝的紅細(xì)胞較小且呈橢圓形，這意味著即使血液因極度脫水而變稠，紅細(xì)胞也可以更容易地流動(dòng)。

For our most indefatigable species then,the secrets of survival in hostile conditions are literally in the blood.

這種最不知疲倦的物種，其在極端條件下生存的秘密，其實(shí)就藏在他們的“血液”里。