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SSS 2010-04-16

时间:2010-06-11 01:54来源:互联网 提供网友:swalloer   字体: [ ]
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Invasive species can decrease biodiversity and drive resident species to the brink1 of extinction2. But how do these interlopers fare so well in unfamiliar3 territory? One idea is that they’ve escaped their enemies, for example, the parasites5 that keep them in check on their home turf. But a study in the journal Biology Letters suggests that notion doesn’t always stand up. Because at least one kind of invasive shrimp6 is an even bigger pest when it has a parasite4 on board.

The scientists were studying a freshwater shrimp commonly found in England. Fishermen brought the shrimp to Northern Ireland in the 1950s as a tasty treat for local trout7. Well, the shrimp liked the new digs. So much that they’ve all but eliminated the native shrimp species. The strange thing is, they may have parasites to thank.

In some streams, 70 percent of the invaders8 are infected with an intestinal9 worm that doesn’t go for the native shrimp. But this gut10 worm doesn’t slow them down. In fact, infected shrimp eat 30 percent more prey11 than those that are parasite-free.

Which perhaps is not surprising. If you had a worm that constituted a quarter of your body weight, you’d eat more too.

Thanks for the minute for Scientific American's 60-Second Science. I'm Karen Hopkin.


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1 brink OWazM     
n.(悬崖、河流等的)边缘,边沿
参考例句:
  • The tree grew on the brink of the cliff.那棵树生长在峭壁的边缘。
  • The two countries were poised on the brink of war.这两个国家处于交战的边缘。
2 extinction sPwzP     
n.熄灭,消亡,消灭,灭绝,绝种
参考例句:
  • The plant is now in danger of extinction.这种植物现在有绝种的危险。
  • The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。
3 unfamiliar uk6w4     
adj.陌生的,不熟悉的
参考例句:
  • I am unfamiliar with the place and the people here.我在这儿人地生疏。
  • The man seemed unfamiliar to me.这人很面生。
4 parasite U4lzN     
n.寄生虫;寄生菌;食客
参考例句:
  • The lazy man was a parasite on his family.那懒汉是家里的寄生虫。
  • I don't want to be a parasite.I must earn my own way in life.我不想做寄生虫,我要自己养活自己。
5 parasites a8076647ef34cfbbf9d3cb418df78a08     
寄生物( parasite的名词复数 ); 靠他人为生的人; 诸虫
参考例句:
  • These symptoms may be referable to virus infection rather than parasites. 这些症状也许是由病毒感染引起的,而与寄生虫无关。
  • Kangaroos harbor a vast range of parasites. 袋鼠身上有各种各样的寄生虫。
6 shrimp krFyz     
n.虾,小虾;矮小的人
参考例句:
  • When the shrimp farm is built it will block the stream.一旦养虾场建起来,将会截断这条河流。
  • When it comes to seafood,I like shrimp the best.说到海鲜,我最喜欢虾。
7 trout PKDzs     
n.鳟鱼;鲑鱼(属)
参考例句:
  • Thousands of young salmon and trout have been killed by the pollution.成千上万的鲑鱼和鳟鱼的鱼苗因污染而死亡。
  • We hooked a trout and had it for breakfast.我们钓了一条鳟鱼,早饭时吃了。
8 invaders 5f4b502b53eb551c767b8cce3965af9f     
入侵者,侵略者,侵入物( invader的名词复数 )
参考例句:
  • They prepared to repel the invaders. 他们准备赶走侵略军。
  • The family has traced its ancestry to the Norman invaders. 这个家族将自己的世系追溯到诺曼征服者。
9 intestinal DbHzX     
adj.肠的;肠壁;肠道细菌
参考例句:
  • A few other conditions are in high intestinal obstruction. 其它少数情况是高位肠梗阻。 来自辞典例句
  • This complication has occasionally occurred following the use of intestinal antiseptics. 这种并发症偶而发生在使用肠道抗菌剂上。 来自辞典例句
10 gut MezzP     
n.[pl.]胆量;内脏;adj.本能的;vt.取出内脏
参考例句:
  • It is not always necessary to gut the fish prior to freezing.冷冻鱼之前并不总是需要先把内脏掏空。
  • My immediate gut feeling was to refuse.我本能的直接反应是拒绝。
11 prey g1czH     
n.被掠食者,牺牲者,掠食;v.捕食,掠夺,折磨
参考例句:
  • Stronger animals prey on weaker ones.弱肉强食。
  • The lion was hunting for its prey.狮子在寻找猎物。
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