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SSS 2011-04-25

时间:2011-05-12 05:36来源:互联网 提供网友:wp661375   字体: [ ]
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    (单词翻译:双击或拖选)

This is Scientific American's 60-Second Science. I'm Cynthia Graber. This will just take a minute.

Take a fire ant—don't forget your gloves. Toss it in water, and it'll eventually drown. But throw a group of fire ants into the water, come back the next day, and they'll still be floating.

Ants are known for cooperative behavior. A species of fire ant called Solenopsis invicta originated in the rainforests of Brazil. It adapted to the region's frequent flooding by building rafts—made up of big groups of the ants themselves. These allow the ants to float, sometimes for months.

Scientists wanted to know how. They collected fire ants from roadsides in Georgia. They placed the ants in water in groups of 500, 3000, and 8000. The ants quickly group together. Half get stuck underneath1 in a single layer—but there are small pockets of trapped air that likely prevent them from drowning.

The ants connect by gripping each others' mandibles and claws. The scientists say it's similar to weaving waterproof2 fabric3. The resulting two-layer raft is cohesive4, buoyant and water-repellent. The research was published in the Proceedings5 of the National Academy of Sciences.

This discovery could help roboticists interested in building self-assembling flotation devices. Or just satisfy our curiosity about how ants cooperate to stay afloat.

Thanks for the minute. For Scientific American's 60-Second Science, I'm Cynthia Graber.


点击收听单词发音收听单词发音  

1 underneath VKRz2     
adj.在...下面,在...底下;adv.在下面
参考例句:
  • Working underneath the car is always a messy job.在汽车底下工作是件脏活。
  • She wore a coat with a dress underneath.她穿着一件大衣,里面套着一条连衣裙。
2 waterproof Ogvwp     
n.防水材料;adj.防水的;v.使...能防水
参考例句:
  • My mother bought me a waterproof watch.我妈妈给我买了一块防水手表。
  • All the electronics are housed in a waterproof box.所有电子设备都储放在一个防水盒中。
3 fabric 3hezG     
n.织物,织品,布;构造,结构,组织
参考例句:
  • The fabric will spot easily.这种织品很容易玷污。
  • I don't like the pattern on the fabric.我不喜欢那块布料上的图案。
4 cohesive dWdy2     
adj.有粘着力的;有结合力的;凝聚性的
参考例句:
  • She sealed the parcel with cohesive tape.她用粘胶带把包裹封起来。
  • The author skillfully fuses these fragments into a cohesive whole.作者将这些片断巧妙地结合成一个连贯的整体。
5 proceedings Wk2zvX     
n.进程,过程,议程;诉讼(程序);公报
参考例句:
  • He was released on bail pending committal proceedings. 他交保获释正在候审。
  • to initiate legal proceedings against sb 对某人提起诉讼
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