【科学60秒】青蛙也练“铁肚功”_英语听力练习mp3下载-自然-沪江听力酷

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【科学60秒】青蛙也练“铁肚功”

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You’d think an animal that ___1___ would know how to land. But for a kind of frog, that’s not the case. Imagine trying to catch a frog. You reach and they jump, only to land gracefully on their feet a few feet away.
It was thought that all frogs moved this way. They'd push off with their back legs, and then once in flight, rotate the limbs forward. Then they landed ___2___ first. But researchers compared frogs of the family Leiopelmatidae, which still ___3___ an ancient physiology, to two more modern frog species. Unlike their more graceful cousins, the primitive frogs kept their back legs straight out after they jumped. So they don’t land on their feet. Instead, they do an ___4___ belly flop, and then struggle to get to their feet and jump again. The finding is in the journal Naturwissenschaften.
The scientists say that the back-leg push-off must have evolved first, with the ability to rotate and land softly evolving later. Although the bad landers are still around, their more controlled relatives appear to be better at making longer trips, ___5___ for food and, most importantly, avoiding other animals that have an interest in frog legs—for dinner.