题目内容
Some fish form huge schools. Could fish set up schools and teach their children how to survive in the ocean? You may ask. No. Here the “schools” are not the places where you study. They are fish shoals (鱼群) that cover tens of kilometers. What causes hundreds of millions of fish to gather and move together is one of biology’s mysteries.
Darkness appears to be the first step to the creation of shoals, according to a study published in the March 27 journal Science. A team of researchers from the Massachusetts Institute of Technology (MIT) and five other institutions studied Atlantic herring (鲱鱼), which forms shoals on a fishing ground off Massachusetts. They used an underwater imaging technology and fish-finding sonar (声纳) to observe the herring over several days in autumn when they spawn (产卵).
They found that, as the sun set, fish in scattered (分散的) groups began swimming much closer to one another than they normally do. When the number of fish reached a certain point in an area, this set off a chain reaction of similar behavior that spread like a sound wave through the water.
The herring’s movement seemed to be started by sunset. The team didn’t record the breakup of these shoals, but a previous study suggested that as the sun rose, the shoals fell apart.
“When the light fades (逐渐消失), it’s safer for the fish to move away from the seabed,” says Nicholas Makris, a professor at MIT who led the research. “Once they have a certain number of other fish, they suddenly come together - forming a shoal covering tens of kilometers within tens of minutes.”
Herring form shoals to migrate during the autumn spawning season. Some shoals were 40 km across and 30 m from top to bottom. They formed in deep water and moved into more shallow waters to spawn.
Forming shoals helps protect them from predators (掠食者) by giving them simple strength in numbers. The ordered movement of the shoal means the fish can reach their spawning ground more quickly and more safely.
Scientists have never before gathered information on so many animals acting together. Understanding these herring shoals could lead to more ideas about what causes animals to move in schools, says Iain Couzin, a biologist at Princeton University, US.
1. Which school in the following expressions is used the same way as the underlined one in the first paragraph?
A. schools of thoughts B. school a horse C. a school of whales D. a medical school
2. Which of the following statements is true?
A. There are more large shoals of herring at night than in the daytime.
B. The research on Atlantic herring was conducted independently by the Massachusetts Institute of Technology.
C. The larger the shoal of herring is, the more slowly it moves.
D. Scientists have found out the reason why fish gather and move together in huge shoals.
3. According to the research, herring tend to get together except ______.
A.when there are predators around B. when they spawn C. when the sun sets D. when the sun rises
4. What seems to be the main reason for herring to gather and move together?
A. To avoid the darkness.
B. To keep other kinds of fish out of their spawning ground.
C. To spawn in the shallow waters.
D. To make themselves feel safe.
【小题1】C
【小题2】A
【小题3】D
【小题4】D
解析
名师金手指领衔课时系列答案A new United Nations report shows that fish farming may soon be the world’s most important provider of fish. The Food and Agriculture Organization says fish farming is growing at a rate of 6.6 percent a year.
Fish farming now produces forty-six percent of the world’s supply of fish. That represents a forty-three percent increase from 2006. The report also said fish farming earned more money in 2008 than traditional fisheries.
In fish farming, fish are raised in tanks or small bodies of water called ponds. They are also raised in cages or nets in oceans, lakes and rivers. The report says increased fish farming has helped people around the world eat record amounts of fish. The FAO says each person ate an average of almost seventeen kilograms of fish last year.
However, the FAO says the current yearly wild-fish harvest of ninety million tons shows no improvement. Decreasing numbers of fish and stronger catch limits have reduced the possibilities for catching wild fish. The FAO report says about thirty-two percent of world supplies are overfished. It says these supplies of fish need to be rebuilt at once.
Some scientists have criticized fish farming. They say the nets and cages permit fish diseases and pests to spread. Some fish farming critics doubt whether fish farming can keep growing at the current rate. But Wally Stevens of the trade group Global Aquaculture Alliance says the industry must continue developing to feed growing populations. Mr. Stevens says a one hundred percent increase in fish farming over ten years is necessary to keep providing for people at the current level. He notes that fish farming creates jobs and wealth, especially for people in coastal areas of China.
【小题1】We learn that since the year 2006, fish farming has been ______.
| A．earning more money than traditional fisheries |
| B．developing rapidly around the world |
| C．growing at a rate of 6.6 percent each day |
| D．producing 46% of the world’s supply of fish |
| A．buy more kinds of fishes | B．eat more fish than before |
| C．eat much healthier fish | D．eat much bigger fish |
| A．it is harder to catch wild fish than before. |
| B．It costs too much to rebuild supplies of fish. |
| C．There is no future for the market of wild fish. |
| D．Catching wild fish no longer brings benefits. |
| A．It doesn’t have disadvantages at all. |
| B．It cannot keep growing at the current rate. |
| C．It is not a good way of raising fish. |
| D．It must develop fast to supply a growing population. |