【英语时差8,16】虫子，涟漪与水上行走-下（在线收听）

How Do Water Bugs Move? The answer lies in the little dimples that a water bug’s feet make in the otherwise flat surface. If the water’s surface really stayed as flat as ice, the bug wouldn’t be able to move. Those dimples give it some grip. Here’s how it works: The back side of each dimple provides an angle for the bug’s leg to push against. Even though the bug’s push makes the dimple move slightly backwards in the water, there’s still enough purchase for the bug to push itself forward. It’s like jogging through soft, dry sand. Our feet push the sand backward, which makes running a lot harder, but we can still move forward.