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托福听力练习-科学美国人60秒:蛇毒的粘性

2017-05-03 14:14:00来源：科学美国人60秒

点击查看>>科学美国人60秒音频：蛇毒的粘性

　　科学美国人60秒听力练习：蛇毒的粘性

　　科学美国人60秒英文文本

　　Snakes are misunderstood. They’re not slimy. They’re not charmed by music. And the poisonous ones don’t all inject venom into their prey through hollow needlelike fangs. In fact, the fangs of most toxic serpents have external grooves that direct the flow of poison. And the venom’s viscosity is key to getting it where it needs to go. So says a study in the journal Physical Review Letters. [Bruce Young et al., "Tears of Venom: Hydrodynamics of Reptilian Envenomation"]

　　Okay, some snakes do use the "hollow fang trick" to take care of their prey. Rattlesnakes, for example. But most snakes have solid fangs, which they use to punch holes in their victims’ skin before they let the venom fly—or slide. Those fangs tend to have grooves that help direct the flow. But scientists got to wondering how that approach could be effective. Couldn’t struggling prey simply brush off the poison as it trickles?

　　Turns out that the venom’s viscosity keeps it nestled in the groove. And when a fang penetrates the victim’s tissue, the groove makes a canal that generates suction. That suction pulls the venom into the wound. But it also makes the venom less viscous, allowing it to move even faster into the prey. Because getting bitten by a snake sucks.

　　—Karen Hopkin

　　中文翻译请点击下一页

本文关键字: 托福听力 科学美国人60秒

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