English 中文网 漫画网 爱新闻iNews 翻译论坛
中国网站品牌栏目(频道)
当前位置: Language Tips> 合作专区> 英语学习专栏

树獭的隐居生活
The Hidden Lives of Sloth

[ 2010-09-28 10:08]     字号 [] [] []  
免费订阅30天China Daily双语新闻手机报:移动用户编辑短信CD至106580009009

还记得《冰河世纪》里那只嗜食而又聒噪,但却极其可爱的树獭希德吗?生长在南美洲的树獭是动作最缓慢的哺乳动物,平均走一步要12秒,比乌龟还慢。而树獭除了爱睡觉之外,也是超级卡哇伊,稚气无邪的模样谁看了也忍不住顿生怜意。下面,我们就来见识一下树獭的隐居生活吧!

树獭的隐居生活

卓言 选 岳晓玲 译

Native to Central and South American rain forest, the sloth is the slowest animal on the planet, so immobile that algae[1] grow on its brown furry back. Sloths have a short and flat head, big round eyes, a snout that is short in length, long tree-climbing legs, a stubby tail and small ears and though some have called them ugly, they have the cutest face that looks like they are always smiling[2].

All sloths spend most of the day asleep, curled up in a tree notch or hanging from a branch with all four legs close together and their heads tucked between their front legs, but even when they are awake you won’t see them move much. At feeding time, sloths move slowly and carefully, hand over hand through the treetops, searching for leaves, buds, fruits, and twigs. They even mate and give birth while suspended from their long, curved claws. Sometimes a sloth will die hanging upside down from a tree limb and remain so after death, until they decompose[3] or are forcibly removed.

Why do sloths have such an unusual lifestyle? It’s the strategy they evolved to survive as tree-dwelling plant eaters in a place with many predators[4].

Most domestic herbivores, such as cattle, horses, and sheep, graze all day long[5]. Because they feed on nutrient-poor vegetation, they must eat almost constantly. Sloths are also herbivores, and their diets are also low in nutrition; but rather than munching placidly all day long, they have become masters at conserving energy[6].

As any athlete knows, maintaining muscle requires large quantities of food energy—far more than a sloth’s vegetarian diet can provide. Because sloths are relatively inactive and spend most of their time hanging upside down, they can get by with half as much muscle mass as similar-sized mammals. As a result, they don’t need to eat as much.

And because muscle is heavy, sloths weigh far less than other mammals their size. This makes it possible for them to climb on thin branches high in the tropical forest canopy, where they can more easily find food and avoid heftier[7] predators.

Maintaining a high body temperature also takes energy. Sloths reduce this cost by maintaining a lower average body temperature than other mammals. Dogs, cats, horses, sheep, rabbits, pigs, and cows all have average body temperatures between 100 and 103°F, but a sloth’s average body temperature is 93°F.

Just as important, a sloth’s body temperature fluctuates with the ambient[8] temperature. Like snakes, frogs, and other “cold-blooded” creatures, a sloth’s body temperature is highest on warm, sunny days, and lowest at night and on rainy days. Sometimes a sloth sunbathes in the morning to warm up. Then, during the hottest part of the day, it hides in the shade so it won’t overheat. During a 24-hour period, a sloth’s body temperature may vary as much as 10°F. If the body temperature of a person, a dog, or a cow varies just 5°F, it can be life threatening.

Because sloths have difficulty moving over land, they spend most of their time in the trees. They can get just about everything they need high above the forest floor—even water, which comes from eating juicy leaves and licking up drops of morning dew. Short bursts of feeding followed by long periods of inactivity make sloths less vulnerable to large raptors such as harpy eagles and other carnivores such as ocelots[9]. As long as sloths remain perfectly quiet and still, they’re nearly impossible to detect.

At feeding time, a sloth reaches out, grabs an overhead branch with its flexible feet, and tugs until the food is within reach of its long tongue. After pulling the vegetation into its mouth, the sloth clips[10] the leaves with its hard, tough lips and slowly grinds them with large, peg-like teeth.

A sloth digests its food just as it does everything else—very slowly. People usually digest their food in about a day, but in sloths, the process may take a month. As soon as a sloth swallows a mouthful of pulverized plants, the bacteria in its stomach and intestines begin breaking down the food[11]. It takes many hours for the bacteria to digest the tough plant material that makes up a sloth’s diet. Only then can the sloth absorb the nutrients it needs to live and grow.

Even the fur of sloths is adapted to their lifestyle. Because sloths hang upside down, their stiff, wiry fur grows differently from the coats of most mammals. Horses’ hair, for example, grows from the back downward toward the belly, but sloths’ fur grows from the belly toward the back, so rainwater will run off. Below this tough top layer, a dense downy layer of hair provides additional protection from pesky insects[12].

The greenish cast of the sloth’s shaggy fur is caused by symbiotic algae that grow in grooves running along the length of each of the mammal’s outer hairs[13]. The sloth hosts the algae, and the algae return the favor by providing nutrients that the sloth either ingests[14] by licking its fur or absorbs through its skin. The grayish-green color makes the sloth look just like a clump of dry leaves hanging from a branch—the perfect jungle camouflage[15]. And the longer a sloth lives, the greener it gets.

Slow and lazy are two different things. The grace, balance, and its hospitality toward the other creatures that depend on it—are traits we could aspire to emulate[16].

树獭生活在中、南美洲的热带雨林中,是地球上行动最缓慢的动物。由于长期不动,它们棕褐色、毛茸茸的背上竟长出了藻类。树獭的头小巧而扁平,一双大眼睛圆圆的,鼻子不长,长腿擅于攀爬,尾巴粗而短小,耳朵也生得小巧玲珑。尽管有人认为它们生得丑陋,但它们的面庞却极其可爱,看上去似乎总是笑呵呵的。

树獭一天大部分时间都在睡觉。睡觉时,它们蜷缩在树坳处或是倒挂在树枝上,四肢蜷在一起,头则缩起来藏于前肢之间。然而,即使它们醒着的时候,人们也几乎看不到它们活动。只有在需要进食的时候,树獭才会慢慢悠悠、小心翼翼、一步一步地爬到树梢,寻些树叶、嫩芽、果实或是细枝来吃。即使交配乃至生产的时候,它们也用那弯曲修长的爪子倒挂在树上。有时,树獭会倒挂在树枝上死去,死后仍挂在树上,直到尸体腐烂或被强行移走。

树獭的生活习性为什会如此与众不同呢?作为一种以树为家的植食动物,树獭每天面临着诸多捕食者,此种习性正是它们历久经年进化而来赖以生存的策略。

大部分家养的食草动物如牛、马、羊,整天都在吃草,这是因为它们所吃的植物营养含量较低,所以必须不停地进食。然而,尽管树獭也是食草动物,食物的营养含量也不高,但它们却不用成天都安静地大嚼,这是因为它们已经进化成了储存能量的高手。

运动员们都知道,维持肌肉需要大量摄食以获取能量——这一目标所需的能量远多于树獭的素食可以提供的能量。而由于树獭相对怠惰,大部分时间都倒挂在树上,它们只需同等大小的哺乳动物一半的肌肉量。所以,它们不需要吃很多食物。

另外,由于肌肉重量较大,树獭比其他同等大小的哺乳动物轻很多。这样,它们便可以轻松地爬上热带雨林上层林冠的细枝,在那里,食物更易获取,体重较大的捕食者也不易企及。

要使身体保持较高的温度同样需要能量。树獭的平均体温比其他哺乳动要低,这样就减少了能量消耗。狗、猫、马、羊、兔、猪和牛的平均体温均在华氏100到103度之间,而树獭的平均体温只有华氏93度。

同样重要的是,树獭的体温会随着环境温度的变化而调整。如同蛇、青蛙或其他“冷血”动物一样,树獭的体温在阳光灿烂的晴天最高,夜晚和阴雨天体温则最低。有时,树獭会在早上来个日光浴以使自己变暖和。而在一天中最热的时候,它会躲在阴凉处以免身体过热。一天24小时中,树獭的体温变化幅度高达10华氏度。而人类、狗或牛的正常体温24小时中仅仅变化5华氏度就可能危及生命。

树獭在陆上行动非常不便,因而,它们大部分时间都待在树上。在那里,它们可以获得一切所需的东西,甚至是水——它们可以通过摄食一些多汁的树叶或舔食树叶上的露珠来汲取水分。短暂的进食后,树獭又开始了长时间的倦怠生活,这种状态使得树獭不易被角鹰这样的大型猛禽和猎豹这样的食肉动物捕食。如果树獭能保持绝对静默不动,它们几乎无法被发现。

进食的时候,树獭会用它灵活的爪子去够头顶的树枝,将其一直往下拽到长舌可以够得着的地方。把食物放进嘴里之后,树獭会用其坚硬的嘴唇将树叶钳住,而后以其大大的像钉子一样的牙齿将食物慢慢嚼碎。

树獭消化食物和它做其他事情没有什么区别——同样极其缓慢。人类通常只需一天就可以将所吃的食物消化,而树獭却可能需要一个月。一旦将嘴里已嚼碎的食物咽下去,树獭胃和肠道中的细菌就开始分解食物。很多个小时之后,这些细菌才能将树獭所吃的顽韧的植物消化掉。之后,树獭才可以吸收维持其生存所需的养分。

连树獭的皮毛也是为适应其生活方式所生。由于树獭总是倒挂在树上,它们坚硬而蓬松的毛发与大部分哺乳动物的生长方式不同。举例来说:马的毛发从身体后面顺着向下生长直至腹部,树獭的皮毛却恰好相反。这样的好处是雨水可以顺着皮毛流走。在这层坚硬的表皮下,还生长着一层细密的绒毛,为防范讨厌的昆虫提供了一层额外保护。

树獭的毛发蓬松而呈绿色,这是因为与其共生的藻类沿着其外层的皮毛的纹路生长。树獭像主人一样招待这些藻类,而藻类则向其提供养分作为回报。树獭通过舔舐皮毛或者皮肤直接吸收的方式摄取这些养分。灰绿色的皮毛也使树獭看上去酷似挂在树枝上的一丛干树叶——完美的丛林伪装。树獭的年岁越长,皮毛便越绿。

行动缓慢并不等同于懒惰。树獭的优雅、镇定和接纳身上赖其为生的其他生物的热情好客——这些品质都是我们应该努力学习的。

(来源:英语学习杂志)

Vocabulary:

1. algae: 藻类。

2. snout: 鼻子;stubby: 粗而短的。

3. decompose: 腐化。

4. predator: 食肉动物。

5. herbivore: 食草动物;graze: 吃草。

6. munch: 用力咀嚼;placidly: 静静地。

7. hefty: 重的。

8. ambient: 周围的。

9. raptor: 猛禽;harpy eagle: (中、南美的)角鹰,短翼鹰;ocelot: 豹猫。

10. clip: 夹紧,钳牢。

11. pulverized: 粉碎的;intestine: 肠。

12. downy: 绒柔的,柔和的;pesky: 讨厌的。

13. shaggy: 毛发蓬松的;symbiotic: 共生的。

14. ingest: 摄取。

15. camouflage: 伪装。

16. emulate: 模仿。

 
中国日报网英语点津版权说明:凡注明来源为“中国日报网英语点津:XXX(署名)”的原创作品,除与中国日报网签署英语点津内容授权协议的网站外,其他任何网站或单位未经允许不得非法盗链、转载和使用,违者必究。如需使用,请与010-84883631联系;凡本网注明“来源:XXX(非英语点津)”的作品,均转载自其它媒体,目的在于传播更多信息,其他媒体如需转载,请与稿件来源方联系,如产生任何问题与本网无关;本网所发布的歌曲、电影片段,版权归原作者所有,仅供学习与研究,如果侵权,请提供版权证明,以便尽快删除。
 

关注和订阅

人气排行

翻译服务

中国日报网翻译工作室

我们提供:媒体、文化、财经法律等专业领域的中英互译服务
电话:010-84883468
邮件:translate@chinadaily.com.cn