英语时差:眼镜蛇
Don: Hey Yaël, why are you wearing safety goggles? Yaël: In case I run into any spitting cobras, Don. D: Spitting cobras? I didn't know there were any wild cobras in the United States. Y: There aren't. Cobras live in Africa and Asia where they kill thousands of people each year, but I'm going to the reptile exhibit at the zoo. The scary thing is, some cobra species don't even have to bite you to injure you. They can spit poison a distance of three feet and they always aim for the eyes . Their poison is a neurotoxin that causes pain and can damage the mucus membranes and cornea. It can even cause blindness. D: Wow. Y: And that's not all. Scientists have found that they can hit a target about two feet away with one-hundred-percent accuracy. D: I don't think I could spit that well. Y: The snakes don't really spit. The poison is released from openings in the front of their fangs. 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 the poison over an area. D: So, it's like using a shot gun with lots of pellets instead of a rifle with a single bullet. Y: Exactly. The snakes don't need to aim perfectly, they just need to be close. D: That is interesting, Yaël. But aren't the zoo snakes in glass enclosures? Y: I imagine so. But better safe than sorry.
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