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This is Scientific American's 60-Second Science. I'm Christopher Intagliata. Got a minute?
A hungry fish can kill prey1 with a quick bite. That is, of course, if its prey hasn't already died of fright. Take tasty dragonflies. The mere2 presence of predators3—even caged ones—is enough to scare dragonflies to death, according to a study in the journal Ecology.
Researchers collected wild dragonfly larvae4, and placed them in tanks with fish or insect predators. The larvae could see and smell their hunters—but were kept safe by underwater cages. After two months, the researchers took a head count—and found that dragonfly larvae sharing quarters with their killers5 were two to four times as likely to die off, compared to counterparts living in predator-free waters. And they had slimmer chances of surviving metamorphosis, too.
The authors suggest a couple reasons why. First, prey tend to make fewer forays for snacks when predators are lurking6 around, so they may not be as nutritionally fit. And previous studies have shown that the presence of predators ups stress levels in prey, weakening their immune systems and making them more vulnerable to disease—and death.
As if being eaten wasn't enough to worry about, looks can kill too.
Thanks for the minute. For Scientific American's 60-Second Science, I'm Christopher Intagliata.
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1 prey | |
n.被掠食者,牺牲者,掠食;v.捕食,掠夺,折磨 | |
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2 mere | |
adj.纯粹的;仅仅,只不过 | |
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3 predators | |
n.食肉动物( predator的名词复数 );奴役他人者(尤指在财务或性关系方面) | |
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4 larvae | |
n.幼虫 | |
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5 killers | |
凶手( killer的名词复数 ); 消灭…者; 致命物; 极难的事 | |
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6 lurking | |
潜在 | |
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