英语听力文摘 English Digest 563、植物的自我防御！

 　　Plant Self-defense¹

 

　　Plants may appear to be helpless in the face of hungry,toothy animals but many plants have evolved interesting systems of self-defense.

 

　　Coarse meadow grasses are a good example. If you run your finger along a blade of coarse grass, you just might cut yourself. What makes it so sharp? A row of microscopic² silica blades lines the grass like tiny teeth, and most grasses have silica inside as well. Although the silica doesn’t prevent animals from feasting on the grass, it is hard enough to wear down the animals’ teeth over time. Imagine trying to chomp³ that tough meadow grass with dull, worn teeth, you wouldn’t get too far!

 

　　The grasses must have evolved this bristling⁴ defense fairly early in their relationship with grazing animals, because the anatomy⁵ of the animals’ mouths has changed in response. The teeth of most mammals stop growing in adulthood⁶. But, the teeth of grazing animals like horses and cows have evolved in a different way. They continue to grow from the roots over the course of the animals’ lives. As the grasses’ silica blades wear away the teeth, continuous growth from the roots at least partially⁷ compensates⁸ for the loss. If an animal’s diet consists mostly of coarse meadow grasses with silica blades, the animal still could develop extensive wearing and damage to its teeth.

 

 

 

　　植物的自我防御！

 

　　植物在饥饿的咀齿动物面前似乎毫无防御 ，然而许多植物已经进化出了有趣的自我保护体系。

 

　　粗糙的蓝草是一个很好的例子。当你的手指滑过它的叶子，很可能将自己划伤。那么它为什么如此锋利呢？因为在蓝草叶片边缘有一排细小的像牙齿似的硅片，并且 大部分蓝草体内也含有硅。虽然这些硅质不能阻止动物的尽情咀嚼，但它的硬度很高，长期食用会磨损动物的牙齿。试想一下，用又老又钝的牙齿咀嚼那样的牧草， 显然不会逍遥很久。

 

　　蓝草一定很早以前就在与草食动物的“对抗”中进化出这种密集的齿状硅片。因为动物的口腔结构发生了相应的变化。大多数哺乳类动物的牙齿在成年以后就停止了 生长。但是马和牛等食草动物的牙齿，却产生了不同的进化。它们从牙根不断生长，贯穿动物的整个生命周期。由于蓝草的硅片磨损牙齿，从牙根不断生长的牙至少 部分弥补了磨损。如果食草动物的食物以这种粗糙蓝草为主，那么磨损仍会加剧并对牙齿造成伤害。

1 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

2 microscopic   

adj.微小的，细微的，极小的，显微的

参考例句：

• It's impossible to read his microscopic handwriting.不可能看清他那极小的书写字迹。
• A plant's lungs are the microscopic pores in its leaves.植物的肺就是其叶片上微细的气孔。

3 chomp   

v. （人、动物进食时）大声地咬，嚼得很响

参考例句：

• I lost a tooth while chomping on a French baguette!我啃法棍面包时，崩掉了一颗牙！
• They just chomp on tundra, nap a few hours and feast again.它们只是在苔原上大嚼特嚼，睡上几小时，接着再吃。

4 bristling   

a.竖立的

参考例句：

• "Don't you question Miz Wilkes' word,'said Archie, his beard bristling. "威尔克斯太太的话，你就不必怀疑了。 "阿尔奇说。他的胡子也翘了起来。
• You were bristling just now. 你刚才在发毛。

5 anatomy   

n.解剖学，解剖；功能，结构，组织

参考例句：

• He found out a great deal about the anatomy of animals.在动物解剖学方面，他有过许多发现。
• The hurricane's anatomy was powerful and complex.对飓风的剖析是一项庞大而复杂的工作。

6 adulthood   

n.成年，成人期

参考例句：

• Some infantile actions survive into adulthood.某些婴儿期的行为一直保持到成年期。
• Few people nowadays are able to maintain friendships into adulthood.如今很少有人能将友谊维持到成年。

7 partially   

adv.部分地，从某些方面讲

参考例句：

• The door was partially concealed by the drapes.门有一部分被门帘遮住了。
• The police managed to restore calm and the curfew was partially lifted.警方设法恢复了平静，宵禁部分解除。

8 compensates   

补偿，报酬( compensate的第三人称单数 )； 给（某人）赔偿（或赔款）

参考例句：

• The company compensates her for extra work. 公司因她的额外工作而给她报酬。
• A vertical spring compensates for the weight of the sensing element. 用一根垂直弹簧补偿敏感元件的负荷。