SSS 2011-11-11
时间：2019-01-08 作者：英语课 分类：Scientific American(十一)月
英语课
This is Scientific American's 60-Second Science. I'm Christopher Intagliata. Got a minute?
A hungry fish can kill prey 1 with a quick bite. That is, of course, if its prey hasn't already died of fright. Take tasty dragonflies. The mere 2 presence of predators 3—even caged ones—is enough to scare dragonflies to death, according to a study in the journal Ecology.
Researchers collected wild dragonfly larvae 4, 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 killers 5 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 lurking 6 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.
n.被掠食者，牺牲者，掠食；v.捕食，掠夺，折磨
- Stronger animals prey on weaker ones.弱肉强食。
- The lion was hunting for its prey.狮子在寻找猎物。
adj.纯粹的；仅仅，只不过
- That is a mere repetition of what you said before.那不过是重复了你以前讲的话。
- It's a mere waste of time waiting any longer.再等下去纯粹是浪费时间。
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）
- birds and their earthbound predators 鸟和地面上捕食它们的动物
- The eyes of predators are highly sensitive to the slightest movement. 捕食性动物的眼睛能感觉到最细小的动静。 来自《简明英汉词典》
n.幼虫
- Larvae are parasitic on sheep.幼虫寄生在绵羊的身上。
- The larvae prey upon small aphids.这种幼虫以小蚜虫为食。
凶手( killer的名词复数 )； 消灭…者； 致命物； 极难的事
- He remained steadfast in his determination to bring the killers to justice. 他要将杀人凶手绳之以法的决心一直没有动摇。
- They were professional killers who did in John. 杀死约翰的这些人是职业杀手。