Life in the Clear
Transparent animals let light pass through their bodies the same way light passes through a window.These animals typically live between the surface of the ocean and a depth of about 3,300 feet—as far as most light can reach.Most of them are extremely delicate and can be damaged by a simple touch.Sonke Johnsen, a scientist in biology, says, “These animals live through their life alone.They never touch anything unless they're eating it, or unless something is eating them.”
And they are as clear as glass.How does an animal become seethrough? It's trickier than you might think.
The objects around you are visible because they interact with light.Light typically travels in a straight line.But some materials slow and scatter(散射)light, bouncing it away from its original path.Others absorb light, stopping it dead in its tracks.Both scattering and absorption make an object look different from other objects around it, so you can see it easily.
But a transparent object doesn't absorb or scatter light, at least not very much. Light can pass through it without bending or stopping.That means a transparent object doesn't look very different from the surrounding air or water.You don't see it—you see the things behind it.
To become transparent, an animal needs to keep its body from absorbing or scattering light.Living materials can stop light because they contain pigments(色素) that absorb specific colors of light.But a transparent animal doesn't have pigments, so its tissues won't absorb light.According to Johnsen, avoiding absorption is actually easy.The real challenge is preventing light from scattering.
Animals are built of many different materials—skin, fat, and more—and light moves through each at a different speed.Every time light moves into a material with a new speed, it bends and scatters.Transparent animals use different tricks to fight scattering.Some animals are simply very small or extremely flat.Without much tissue to scatter light, it is easier to be seethrough.Others build a large, clear mass of nonliving jellylike(果冻状的)material and spread themselves over it.
Larger transparent animals have the biggest challenge, because they have to make all the different tissues in their bodies slow down light exactly as much as water does.They need to look uniform.But how they're doing it is still unknown.One thing is clear：for these larger animals, staying transparent is an active process.When they die, they turn a nontransparent milky white.
文章大意：你见过透明生物吗？本文介绍了透明的海洋生物。作者为我们介绍了物体之所以不能透明的原理，从而让我们理解没有什么器官组织的透明生物能够保持透明的奇特性。
1．According to Paragraph 1, transparent animals________.
A．stay in groups B．can be easily damaged
C．appear only in deep ocean D．are beautiful creatures
答案：B 细节理解题。根据文章第一段第三句Most of them are extremely delicate and can be damaged by a simple touch.可知，透明生物非常脆弱，轻轻的触碰都可能使其致命，故选B项。
2．The underlined word “dead” in Paragraph 3 means________.
A．silently B．gradually
C．regularly D．completely
答案：D 词义猜测题。文中画线词所在句的句意为：其他的物质吸收光线，完全阻挡光的传播途径。由后面一句中的look different fromother objects around it以及you can see it easily可知，物体不能透明是因为散射光线和吸收光线，光线被完全吸收时变得不透明。由此可以判断句中的dead是副词，意为“完全地”。
3．One way for an animal to become transparent is to________.
A．change the direction of light travel
B．gather materials to scatter light
C．avoid the absorption of light
D．grow bigger to stop light
答案：C 细节理解题。根据第五段第一句To become transparent, an animal needs to keep its body from absorbing or scattering light.可知，动物要想变透明就需要阻止身体吸收或散射光线，故C项是变透明的一个方法。
4．The last paragraph tells us that larger transparent animals ________.
A．move more slowly in deep water
B．stay seethrough even after death
C．produce more tissues for their survival
D．take effective action to reduce light spreading
答案：D 推理判断题。文章最后一段第一句说较大的透明动物面临巨大挑战，因为它们必须尽可能让所有身体组织像水一样降低光线传播的速度。故选D项。
