英语听力文摘 English Digest 541、冻结的一瞬！！

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　　Suppose you are an animal. Well, actually, you are an animal, but suppose you’re another kind of animal, maybe something small that might make a tasty snack for a larger predator¹. You’re walking along one day when you see a big dog. What do you do?

 

　　Well, depending on what kind of animal you are, you have different options. A skunk² can spray a noxious³ liquid that will repel⁴ predators⁵, a cat can make its hair stand on end so that it seems larger than it is, or some animals, such as opossums, may pretend to be dead already.

 

　　There’s another strategy all these animals have, though. You’ve seen it before, but maybe never thought about it. They can freeze.

 

　　When a squirrel or a rabbit or a chipmunk⁶ freezes, it can remain almost entirely⁷ motionless for minutes at a time. Try it yourself. Whatever position you’re in right now, move nothing at all for the next minute. It’s not so easy!

 

　　The reason an ability to freeze works as a defense⁸ is that a predator’s attack behavior may actually be triggered by motion. A frog, for example, will literally⁹ starve to death in a box full of dead flies. Pass one of those flies in front of its eyes on a little string, though, and it will automatically gulp¹⁰ it down.

 

　　The response to freeze is completely hard-wired, so freezing shows us something about both predator and prey¹¹. Evolution has caused the freeze strategy to come into existence precisely¹² because it fits in with the way the visual systems of predators operate.

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