But how do the chicks break out from the cramped confines of the egg?
小鸡是如何从狭小的鸡蛋中挣脱出来的呢?
How can the shell that's been strong enough to protect the chick from the outside world, be also weak enough to allow the chick to break it?
蛋壳既能保护小鸡不受外界的伤害,又能让小鸡破壳而出?那么它到底有多坚硬呢?
The first breath of fresh air outside the egg.
呼吸到了蛋壳外的第一缕新鲜空气。
A captive-bred jungle fowl chick emerges.
一只人工饲养的原鸡出现了。
It's the climax of the egg's existence.
这是小鸡能否存活的关键时刻。
The shell may look the same as when the egg was laid, but out of sight, it's been changing.
蛋壳看起来可能和刚下蛋的时候一样,但在我们看不见的地方,它已经发生了变化,
It's been getting thinner.
变得越来越薄。
The chick has been absorbing calcium from the shell into its own bones, making itself stronger and the shell weaker.
小鸡从蛋壳里将钙吸收到自己的骨头里,使自己变得更加强壮,而蛋壳则变得更加脆弱。
Not only that, but it also used the shell's calcium to create a tool to help it break free:
不仅如此,小鸡还利用蛋壳里的钙制造了一个工具来帮助自己挣脱:
A hard, jagged tip on the end of its beak—an egg-tooth.
在它的喙尖上有一个坚硬的锯齿状的尖儿——那是一颗蛋牙。
The chick couldn't have broken free without it.
小鸡没有它是不可能挣脱的。
Even so, it can still take hours, sometimes days, to hammer its way out of a shell.
即便如此,它仍可能需要几个小时,甚至几天的时间才能破壳而出。