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Belly-Flopping Frogs Leapt While Still Bad Landers

You’d think an animal that hops 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.

你一定认为会跳的动物就知道如何着地。但有种青蛙不是这样。想象一下抓蛙的情形吧，你靠近，它便纵身一跃，紧接着双腿着地优雅地降落在数英尺开外。

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 fore-limbs first. But researchers compared frogs of the family Leiopelmatidae, which still sports 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 ungainly belly flop, and then struggle to get to their feet and jump again. The finding is in the journal Naturwissenschaften. [Richard Essner et al., Nk4FH]

一般人们认为所有的蛙都是这样：它们后腿蹬地起跳，一旦升空，后肢前摆，前肢后摆，接着前肢先落地。但研究人员对比了滑跖蟾和两类现代蛙后发现情况并非如此。滑跖蟾科仍保有原始生理习性，它与两个优雅的现代近亲不同，起跳之后后肢一直是伸直的，降落时并非腿着地，而是肚子朝下直接扑倒，样子相当难看。之后它会挣扎着爬起来继续跳。这项研究成果发表在《自然科学》杂志上。（作者：理查德·艾斯纳等，Nk4FH）

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, foraging for food and, most importantly, avoiding other animals that have an interest in frog legs—for dinner.

科学家表示，后腿起跳这个动作必然比四肢交替摆动、轻盈落地的能力进化更早。尽管笨拙的“扑地蛙”依旧生存着，比起那些老练的近亲来，它们在运动、捕食领域相形逊色。更重要的是，现代蛙比古蛙更善于躲避猎食者的追捕——尤其是那些喜欢在晚餐来上一只美味蛙腿的猎食者。

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