时差N小时:眼镜蛇喷射毒液时如何百发百中?

Don:Hey Yael, why are you wearing safety goggles?

唐：嘿，雅艾尔，你为什么戴着一副护目镜?

Yael:In case I run into any spitting cobras, Don.

雅艾尔：唐，以防碰上吐毒液的眼镜蛇。

Don:Spitting cobras? I didn't know there were anywild cobras in the United States.

唐：吐毒液的眼镜蛇?我一直以为在美国没有野生的眼镜蛇。

Yael:There aren't. Cobras live in Africa and Asiawhere they kill thousands of people each year, butI'm going to the reptile exhibit at the zoo. The scarything is, some cobra species don't even have to bite you to injure you. They can spit poison adistance of three feet and they always aim for the eyes. Their poison is a neurotoxin thatcauses pain and can damage the mucus membranes and cornea. It can even cause blindness.

雅艾尔：这里没有。眼镜蛇生活在非洲和亚洲，每年有上千人死于这种蛇。但我要去动物园的爬行动物馆参观。可怕的是，有些种类的眼镜蛇不用咬你就可以伤到你。它们能在三尺以内吐出毒液，目标往往是眼睛。它们的毒液是一种神经毒素，能导致疼痛并使粘液隔膜和角膜毁坏。甚至能导致失明。

Don:Wow.

唐：哇。

Yael:And that's not all. Scientists have found that they can hit a target about two feet awaywith one-hundred-percent accuracy.

雅艾尔：那还不是全部。科学家们还发现，它们能在两尺远的地方百分之百地击中目标。

Don:I don't think I could spit that well.

唐：我想我都不能吐唾液到那么远。

Yael:The snakes don't really spit. The poison is released from openings in the front of theirfangs. As it's released, they expel air from their lungs to blow the poison outward.Researchers used high-speed photography to find out how they hit their target every time.Instead of holding their head still to spit, the snakes rotate it from side to side, spreading thepoison over an area.

雅艾尔：蛇不会真的喷射唾液。毒液是从毒牙前部的张口处分泌出来的。毒液释放时，肺部迅速排出空气，将毒液注射到外界。研究人员用高速摄像机捕捉到它们每次是如何命中目标的。与其保持头部静止，蛇会一边旋转头部，一边将毒液散播出去。

Don:So, it's like using a shot gun with lots of pellets instead of a rifle with a single bullet.

唐：那么，这就像使用一杆有很多子弹的散弹枪，而不是只有一发子弹的步枪。

Yael:Exactly. The snakes don't need to aim perfectly, they just need to be close.

雅艾尔：正是。蛇并不需要瞄准的多么精确，离得够近就行了。

Don:That is interesting, Yael. But aren't the zoo snakes in glass enclosures?

唐：雅艾尔，那很有趣。但是动物园里的蛇不是被玻璃墙挡着吗?

Yael:I imagine so. But better safe than sorry.

雅艾尔：我想是的。但是安全起见，以免后悔。