33 Plankton浮游生物. / plж `plжktэn/
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 seas 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 seas 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.
GRE作文题库--社会类
GRE写作常用词汇集锦(一)
GRE作文范文:Argument
GRE作文题库--学习类
新GRE作文新题库解析—issue133
新版GRE作文新题库解析-issue148
新版GRE作文新题库解析-issue138
新版GRE作文新题库解析-issue146
逻辑思路能力带来GRE作文高分
新GRE作文新题库解析issue—139
GRE作文范文分析
新GRE作文新题库解析—issue123
类比:GRE写作绝招
新版GRE作文新题库解析-issue145
GRE写作词汇集锦(二)
新版GRE作文新题库解析-issue144
新GRE作文新题库解析—issue122
GRE高分作文不可不知的八个必须
GRE关于艺术价值写作范文
四种方法写好GRE作文issue
新版GRE作文新题库解析-issue142
GRE作文题库--科技类
新版GRE作文新题库解析-issue136
新版GRE作文新题库解析-issue140
GRE作文高频句式示例(三)
新版GRE作文新题库解析-issue126
新GRE作文新题库解析—issue124
正确看待GRE高频作文
新版GRE作文新题库解析-issue1
新版GRE作文新题库解析-issue127
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |