在线词典,在线翻译

缓慢的生存!!

所属:听力板块 来源:普特英语听力 阅读:1980 次 评论:0 条 [我要评论]  [+我要收藏]

小编摘要:在户外,你可能见过毛毛虫爬来爬去寻找食物或躲避鸟类,但是商用蚕幼虫很少活动。为了产丝,这些蚕就被放在敞口的匾上,因为只要有充足的桑叶供应,它们就 会满足于一动不动地呆着。

 Survival Of The Sluggish



Silkworms have been bred over thousands of years to behave quite unlike their caterpillar cousins in the wild. That’s because people purposely breed silkworms to fit this job description:

WANTED–Superlative silk producers. Benefits include housing, unlimited food and protection from all predators. Wanderlust greatly discouraged. No opportunity for travel.

Obviously, what makes a good silk producer in captivity is very different from what helps a caterpillar survive in the wild. Commercial silkworms are dynamos at silk production, and compared to their wild relatives, rather sluggish about everything else.

Outdoors, you’ve probably seen caterpillars crawling to find food or hide from birds, but commercial silkworm caterpillars hardly move. For silk production, they’re kept on open trays because they’re content to stay put, as long as they have a steady supply of mulberry leaves. Even when they reach the moth stage, commercial silkworms are surprisingly immobile. Wild moths fly to evade predators and to lay their eggs in different areas. However, commercial silkworm moths haven’t needed to do these things for thousands of years. They’ve completely lost the ability to fly, even though they still have wings!

Here’s another difference. In the wild, moths are often very particular about where they’ll lay eggs. This ensures that baby caterpillars can chomp their favorite leaves as soon as they hatch. Commercial silkworm moths have lost that instinct too. They’ll even lay eggs on a sheet of paper, where it’s easy for humans to keep track of them.

缓慢的生存


蚕这种动物已经被人类豢养了上千年,这使得它们的行为远远异于野外的毛毛虫同类们。因为人类故意培养蚕,使得他们能够适应这样的工作岗位:

诚聘:招优秀的产丝工。福利包括住房、包吃包喝、不受天敌威胁。不欢迎旅游迷。没有出差机会。

很明显,造就人工饲养的产丝能手的条件跟让野生毛毛虫在野外生存的能力会非常不同。跟它们的野生同类相比,商用蚕在产丝方面是能手,但在其他任何方面的行动都很迟缓。

在户外,你可能见过毛毛虫爬来爬去寻找食物或躲避鸟类,但是商用蚕幼虫很少活动。为了产丝,这些蚕就被放在敞口的匾上,因为只要有充足的桑叶供应,它们就 会满足于一动不动地呆着。即使商用蚕蜕变成蛾子,它们的活动力也惊人地弱。野生的蛾子会到处飞,以躲避天敌并且把卵产在不同的地方。但是,从上千年前开 始,商用蚕的蛾子就不用做这些事情了。即使它们仍然有翅膀,它们也已对完全丧失了飞行的能力。

还有一处不同。野外的蛾子通常对产卵地点很挑剔。这可以保证它们的幼虫一孵化就能吃到喜欢吃的树叶。商用蚕的蛾子连这种本能也丧失了。它们甚至会在纸张上产卵,对于人类来说可以很方便的找到它们。

标签:听力文摘
2
2012-04-09 18:56 编辑:pliny
分享到:
关注海词微博:
发表评论:
表达一些您的想法吧!已有0条评论>>
登录,再发表评论
文明上网,理性发言!
您可能还感兴趣的文章:
  • [听力板块]身体,你怎么啦?

    每次生病了,家里人最多说的一句话就是“不吃药怎么行?”。可是,有的时候吃药不一定就对身体有好处,反而有可能会帮助病原体“攻击”我们的身体。今天我们来了解了解一种新的理论“达尔文医学
  • [听力板块]利刃特别在何处

    大家都知道锋利的刀刃的切割性能胜过钝刀,但您知道确切原因吗?刀刃的作用就是把人们用在刀把上的力集中起来。