题目内容
Fish have ears. Really. They’re quite small and have no opening to the outside world carrying sound through the body. For the past seven years, Simon Thorrold, a university professor, has been examining fish ears, small round ear bones called otoliths.
As fish grow, so do their otoliths. Each day, their otoliths gain a ring of calcium carbonate (碳酸钙). By looking through a microscope (显微镜) and counting (数) these rings, Thorrold can determine the exact age of a young fish. As a fish gets older, its otoliths no longer get daily rings. Instead, they get yearly rings, which can also be counted, giving information about the fish’s age, just like the growth rings of a tree.
Ring counting is nothing new to fish scientists. But Thorrold has turned to a new direction. They’re examining the chemical elements (元素) of each otolith ring.
The daily ring gives us the time, but chemistry tells us about the environment in which the fish swam on any given day. These elements tell us about the chemistry of the water that the fish was in. It also says something about water temperature, which determines how much of these elements will gather within each otolith ring.
Thorrold can tell, for example, if a fish spent time in the open ocean before entering the less salty water of coastal areas. He can basically tell where fish are spending their time at any given stage of history.
In the case of the Atlantic croaker, a popular saltwater food fish, Thorrold and his assistant have successfully followed the travelling of young fish from mid-ocean to the coast, a journey of many hundreds of miles.
This is important to managers in the fish industry, who know nearly nothing about the whereabouts (行踪) of the young fish for most food fish in the ocean. Eager to learn about his technology, fish scientists are now lending Thorrold their ears.
1．What can we learn about fish ears from the text?
A. They are small soft rings. B. They are not seen from the outside.
C. They are openings only on food fish. D. They are not used to receive sound.
2．Why does the writer compare the fish to trees?
A. Trees gain a growth ring each day.
B. Trees also have otoliths.
C. Their growth rings are very small.
D. They both have growth rings.
3．Why is it important to study the chemistry of otolith rings?
A. The elements of the otoliths can tell the history of the sea.
B. Chemical contents (含量) of otoliths can tell how fast fish can swim.
C. We can know more about fish and their living environment.
D. Scientists can know exactly how old a fish is.
4．How would you understand “fish scientists are now lending their ears”?
A. They are very interested in Thorrold’s research findings.
B. They want to know where they can find fish.
C. They lend their fish for chemical studies.
D. They wonder if Thorrold can find growth rings from their ears.
BDCA
There are some things humans can go without. We can lose a kidney or a lung, an arm or two and still live perfectly well. But some fish put us to shame. They can get by without stomachs.
One such fish is the stout longtom. The group it belongs to carries a more appropriate name: the needlefish. All needlefish lack stomachs. Their ancestors had them, but later they were lost.
The stout longtom can reach 1.3 meters in length, and lives near the sea surface. Like all needlefish, it can jump out of the water to escape its enemies. Tropical fishermen are sometimes injured by needlefish. In 1977, a 10-year-old Hawaiian boy was killed when a needlefish jumped through his brain. The longtom eats smaller fish. It teeth are not good at cutting fish into pieces, so it swallows fish whole.
Ryan Day from Australia and his colleagues wanted to know how the longtom digests its meaty meals without a stomach, so they ran some chemical tests about the fish.
Day’s results show that the longtom can consume food without the help of a stomach. It uses a special material called trypsin that can break down proteins without acid — although the approach is less efficient than using a stomach.
Because it’s a meat-eating animal, the longtom gets a lot of protein in its food, so it can afford this slightly less efficient system for absorbing it. Two plant-eating fish that Day studies actually had higher levels of trypsin in their body, as their food was low in protein.
Day thinks that the longtom and its stomachless relatives might actually have arrived at an energy-saving solution. He says that although the stomach is critical to many kinds of animal, the organ is “a fairly expensive organ to run”. This perhaps explains why some animals have got rid of theirs.
【小题1】What does the underlined phrase “get by” mean?
| A．Recover. | B．Fight. | C．Hunt. | D．Live. |
| A．catches smaller fish in the water | B．digests the smaller fish in its body |
| C．can jump so high to escape its enemies | D．uses acid to break down the protein |
| A．Trypsin. | B．Acid | C．The stomach. | D．Protein in its body. |
| A．the longtom can make acid easily |
| B．the longtom often waste energy |
| C．the longtom’s high-protein food helps its unique way of consuming food. |
| D．meat –eating fish have higher levels of trypsin in their bodies than plant-eating fish |
Scientists in Canada say big ocean fish have almost disappeared from the world since the start of industrial fishing in the nineteen-fifties. The scientists found that population of large fish like tuna; swordfish and cod have dropped by ninety percent in the past fifty years.
The study took ten years. The researchers gathered records from fishing businesses and governments around the world. The magazine Nature published the findings.
The scientists say the common method called longline fishing is especially damaging to populations of large fish. This method involves many fishing lines connected to one boat. These wires can be close to one-hundred kilometers long. They hold thousands of sharp metal hooks to catch fish.
Longline fishing is especially common in the Japanese fishing industry. Records showed that Japanese boats used to catch about ten fish for every one-hundred hooks. The study says longline fishing boats now might catch one fish per hundred hooks.
The scientists say industrial fishing can destroy groups of fish much faster than in the past. The study suggests that whole populations can disappear almost completely from new fishing areas within ten to fifteen years.
Ransom Myers of Dalhousie University in Nova Scotia led the study with Boris Worm of Dalhousie and the University of Kiel in Germany. Mister Worm says the destruction could lead to a complete re-organization of ocean life systems. Mister Meyers says the decreased number of large fish is not the only worry. He says even populations that are able to reproduce do not get the chance to live long enough to grow as big as their ancestors(祖先). He says not only are there fewer big fish, they are smaller than those of the past.
American government scientists say even with the best efforts to protect fish populations, decreases are to be expected.
【小题1】Where is the passage probably taken from?
| A．A story book. |
| B．A business magazine. |
| C．An environment report. |
| D．An economic survey. |
| A．longline fishing method is used |
| B．sea water is getting polluted |
| C．mankind destroys the environment |
| D．governments don’t make the best efforts |
| A．Today’s “large”fish are smaller than those of the past. |
| B．Longline boats now might catch fewer fish every one-hundred hooks. |
| C．Fish even able to reproduce don’t have the chance to live longer. |
| D．Japanese boats could catch about ten fish for every 100 hooks. |
| A．Discoveries Canadian Scientists Have Made |
| B．Japanese Fishing Industry |
| C．Losses of Big Fish |
| D．Modern Fishing Methods |
| A．In the 1960s. | B．In the 1970s. | C．In the 1980s. | D．In the 1990s. |