Half a billion years ago, there existed a wormlike creature the size of a grain of rice.

5亿年前，生存着一种体型如米粒大小的蠕虫状生物。

This creature—the fly's early, wormlike phase—is just about capable of sensing its environment, searching for food and avoiding predators.

种生物——苍蝇的早期蠕虫阶段——几乎能够感知其环境、寻找食物和躲避捕食者。

" No, " Pyat screeched. " No, to me, come to me, to meeeeeee" . His face crumbled inward, changing to something pale and wormlike.

" 不，" 俳雅尖。" 不，过来，到我里，到我里里里里里——" 他的脸向内塌陷，逐渐变成苍白的蛆。

It's called a Pikaia and it's a little wormlike creature but it's thought that this is a chordate, and that is the branch of life that we're in, so it could that this is our earliest known ancestor.

卡虫，确实和普通虫子差不多，不过们认为是一种脊索动物，也就是说，和我们是同一类动物，所以也许是我们最早的祖先了。

So eggs are laid in and around sources of water, and then, when it rains, or tides come into the wetlands, these eggs hatch, and out of these eggs hatch these wormlike larvae that swim around in the water.

因此，卵产在水源中和水源周围， 然后，当下雨或潮汐进入湿地时，些卵就会孵化， 并从些卵中孵化出些在水中游来游去的蠕虫状幼虫。