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.
语篇解读 本文是一篇说明文,向读者介绍了透明的动物,并解释了它们透明的原因。
1.According to Paragraph 1, transparent animals ________.
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