新东方优美背诵短文50篇 Unit33:Plankton浮游生物

33 Plankton浮游生物.

Scattered through the seas of the world are billions of tons of small plants and animals called plankton. Most of these plants and animals are too small for the human eye to see. They drift about lazily with the currents, providing a basic food for many larger animals.

Plankton has been described as the equivalent of the grasses that grow on the dry land continents, and the comparison is an appropriate one. In potential food value, however, plankton far outweighs that of the land grasses. One scientist has estimated that while grasses of the world produce about 49 billion tons of valuable carbohydrates each year, the sea’s plankton generates more than twice as much.

Despite its enormous food potential, little effect was made until recently to farm plankton as we farm grasses on land. Now marine scientists have at last begun to study this possibility, especially as the sea’s resources loom even more important as a means of feeding an expanding world population.

No one yet has seriously suggested that “ plankton-burgers” may soon become popular around the world. As a possible farmed supplementary food source, however, plankton is gaining considerable interest among marine scientists.

One type of plankton that seems to have great harvest possibilities is a tiny shrimp-like creature called krill. Growing to two or three inches long, krill provides the major food for the great blue whale, the largest animal to ever inhabit the Earth. Realizing that this whale may grow to 100 feet and weigh 150 tons at maturity, it is not surprising that each one devours more than one ton of krill daily.

浮游生物数十亿吨的被称为"浮游生物"的小动物、植物散布在世界的海洋中。这些小的动、植物大多太小而难以被人眼看到。
它们随波逐流，为许多较大的动物提供了基本的食物。浮游生物曾被描述为生长在大陆陆地上的各种草类的海洋对应物。这种比喻是恰当
的。然而就潜在的食物价值而言，浮游生物远胜于草类。一位科学家曾经估计，世界上的草类每年生产大约490
亿吨有用的碳水化合物，而海洋里的浮游生物每年生产的碳水化合物多于此数的两倍。尽管浮游生物具备巨大的食物潜能，但直到最近人们还很少象种植草类
那样付出努力养殖浮游生物。现在，海洋科学家们至少已开始研究这种可能性。全球人口不断扩张，海洋资源作为食品的重要性日益突出。
现在还没有人认真说过"浮游生物汉堡"会很快在世界上流行起来。然而，作为一种可能养殖的补充性食物资源，浮游生物正引起了海洋科学家们相当大的兴趣。
一种似乎具有很大收获可能性的微小的虾状浮游生物被称为鳞虾。鳞虾长至2～3英寸长时即成为地球上曾居住过的最大动物--蓝鲸的主要食物。成
熟的蓝鲸可以达到100英尺长，150吨重，所以每头鲸每天吞食1吨多的鳞虾一点也不让人吃惊。