SCIENCE IN THE NEWS - All About Sharks

SCIENCE IN THE NEWS - All About Sharks
By George Grow

Broadcast: Tuesday, July 05, 2005

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VOICE ONE:

This is SCIENCE IN THE NEWS in VOA Special English. I'm Barbara Klein.

VOICE TWO:

 
 
And I'm Doug Johnson. On our program this week, we tell about sharks. They are among the oldest animals on Earth. Sharks are famous for attacking other sea creatures and even people. Yet they also have been threatened by human activities.

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VOICE ONE:

Scientists say sharks have lived in the world's oceans for millions of years. Today, sharks live the same way they did more than two hundred million years ago, before dinosaurs¹ existed on the Earth.

 
Tagged shark
Scientists say there are more than three hundred fifty different kinds of sharks. Most sharks are about two meters long. The dogfish shark, however, is less than twenty centimeters in length. And, the biggest whale shark can grow to a length of twenty meters.

Sharks do not have bones. The skeleton² of a shark is made of cartilage. Human noses and ears are also made of cartilage.

VOICE TWO:

A shark has an extremely good sense of smell. It can find small amounts of substances in the water, such as blood, body liquids and chemicals produced by animals. Sharks also sense electrical and magnetic power linked to nerves and muscles of living animals. These powerful senses help them find their food. Sharks eat fish, other sharks, and plants that live in the ocean. Some sharks will eat just about anything. Many unusual things have been found in the stomachs of some tiger sharks. They include shoes, dogs, a cow's foot and metal protective clothing.

VOICE ONE:

Sharks grow slowly. Some kinds of sharks are not able to reproduce³ until they are twenty years old. Most reproduce only every two years. And they give birth to fewer than ten young sharks.

About forty percent of the different kinds of sharks lay eggs. The others give birth to live young. Some sharks carry their young inside their bodies, with a cord connecting the fetus⁴ to the mother, like humans do.

Scientists are beginning to understand the importance of sharks to humans. Medical researchers want to learn more about the shark's body defense⁵ system against disease. They know that sharks recover quickly from injuries.

Sharks appear never to suffer infections, cancer or heart diseases. Many people believe that shark cartilage can help prevent cancer. Scientists have questioned this idea. Yet they still study the shark in hopes of finding a way to fight human disease.

VOICE TWO:

Most sharks live in warm waters, but some can be found in very cold areas. Most sharks live in the oceans. However, the bull⁶ shark leaves ocean waters to enter freshwater rivers and lakes. They have been found in the Zambezi River in Africa, the Mississippi River in the United States, and Lake Nicaragua in southwestern Nicaragua.

Sharks are important for the health of the world's oceans. They eat injured and diseased fish. Their hunting activities mean that the numbers of other fish in the ocean do not become too great. This protects the plants and other forms of life that exist in the oceans.

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VOICE ONE:

People have long feared sharks because of their sharp teeth, aggressive actions and fame as fierce hunters. "Jaws⁷" was the name of a popular book published in nineteen seventy-four. It told about people in an American coastal⁸ town who sought protection from a great white shark that killed swimmers in the ocean. Thirty years ago last month, the film version of the book was released. "Jaws" became one of the most popular American movies in history. The movie was extremely frightening.

However, experts say not all sharks are like the one shown in "Jaws." Still, sharks attacked sixty-one people around the world last year. Twenty-seven of those attacks took place in North American waters. Twelve were in waters near the southeastern state of Florida.

VOICE TWO:

 
Tagged shark
The International Shark Attack File keeps records of all reported shark attacks. The list has been in existence since nineteen fifty-eight. The world attack totals last year were similar to those of the most recent years. Yet the number of attacks has risen during the past century. However, the number of deaths from shark attacks each year around the world remains⁹ very small. Experts say sharks killed only seven people last year.

Shark experts say bees, snakes and elephants kill more people each year than sharks do. They say there is no great need to protect people from sharks.

VOICE ONE:

Many people disagree with that idea. That is because of media reports about shark attacks and resulting deaths. On June twenty-fifth, a shark attacked a fourteen-year-old girl as she swam near the coast of northwestern Florida. The girl was swimming with a friend in the Gulf¹⁰ of Mexico. They were more than ninety meters from the coast when a shark bit one of the girl's legs. A man surfing in nearby waters brought her back to land. But medical workers were unable to save the girl. She died of her wounds.

Two days later, there was another attack about one hundred kilometers east of where the girl died. A sixteen-year-old boy was attacked while standing¹¹ and fishing in waters near an area called Cape¹² San Blas. He survived the attack, but doctors were forced to remove one of his legs.

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VOICE TWO:

Shark experts are attempting to discover why many shark attacks take place within the same general area. They say warm weather conditions may influence both fish and shark activity. The warmer waters moving close to the coast carry many fish to that area. Experts say sharks may have followed the fish into the same area where many people were swimming.

Experts say most sharks bite people by mistake. For unknown reasons, they think that a person is a large sea animal, like a seal or sea lion. That is why people should not go swimming in the ocean at the times of the day when the sun goes down or comes up. Those are the times when sharks are looking for food. Experts also say that people should not wear bright colors or shiny metal jewelry¹³. These may cause sharks to attack.

VOICE ONE:

The experts say shark attacks only seem to be increasing because more people are swimming in the oceans than ever before. They say the number of sharks in the world has decreased in recent years. Scientists say people are killing¹⁴ sharks faster than the sharks can reproduce.

People hunt sharks for sport, food, medicine and their skin. Experts say the international market for some kinds of sharks has increased greatly because many parts of a shark are valuable.

For example, shark meat is good to eat. In Asia, people enjoy a special kind of soup made from shark fins¹⁵. Experts say a fisherman can earn about fifty dollars a kilogram for shark fins. Collectors pay thousands of dollars for the jaws of a shark. Shark liver oil is a popular source of Vitamin A. Some people believe that a shark's cartilage and liver can improve people's health. The skin of a shark can be used like leather.

VOICE TWO:

People also kill sharks because of fear. Many sharks are killed by mistake. Each year, thousands die in traps set out to catch other kinds of fish.

If too many sharks in one area are killed, that group of sharks may never return to normal population levels. Such hunting activities also have made some kinds of sharks in danger of disappearing from Earth.

Many scientists say the number of sharks worldwide has dropped by fifty percent over the past fifteen years. Among some kinds of sharks, the number may have decreased by more than seventy percent. For example, the number of dusky sharks and sandbar sharks off the eastern United States decreased by more than eighty percent. This happened between nineteen eighty-five and nineteen ninety-five. The sand tiger shark and the great white shark are threatened around the world.

Many nations have approved laws to protect the great white shark. These nations include Australia, South Africa, and the United States. Last October, the great white shark gained international protection for the first time. The recognition¹⁶ came at a meeting of the Convention¹⁷ on International Trade in Endangered Species¹⁸ of Wild Fauna¹⁹ and Flora²⁰, or CITES²¹. Delegates²² at the meeting approved a plan to require a permit for selling the jaws, teeth and fins of great white sharks.

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VOICE ONE:

This program was written by Nancy Steinbach and George Grow. Cynthia Kirk was our producer. I'm Barbara Klein.

VOICE TWO:

And I'm Doug Johnson. Join us again next week for Science in the News in VOA Special English.

1 dinosaurs   

n.恐龙( dinosaur的名词复数 )；守旧落伍的人，过时落后的东西

参考例句：

• The brontosaurus was one of the largest of all dinosaurs. 雷龙是所有恐龙中最大的一种。 来自《简明英汉词典》
• Dinosaurs have been extinct for millions of years. 恐龙绝种已有几百万年了。 来自《简明英汉词典》

2 skeleton   

n.骨骼，框架，骨干，梗概，提要

参考例句：

• A long illness made a skeleton out of him.长期的卧病使他骨瘦如柴。
• Her notes gave us just the bare skeleton of her theory.她的笔记只给我们提供了她的理论的梗概。

3 reproduce   

v.生育，繁殖，复制，重做

参考例句：

• The machine can reproduce a key in two minutes.这机器能在两分钟内复制一把钥匙。
• The picture will reproduce well.这照片会印得很清楚。

4 fetus   

n.胎，胎儿

参考例句：

• In the fetus,blood cells are formed in different sites at different ages.胎儿的血细胞在不同时期生成在不同的部位。
• No one knows why a fetus is not automatically rejected by the mother's immune system. 没有人知道为什么母亲的免疫系统不会自动排斥胎儿。

5 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

6 bull   

n.公牛，买进证券投机图利者，看涨的人

参考例句：

• It's only a hair off a bull's back to them.这对他们来说，不过九牛一毛。
• Many dogs closed around the bull.很多狗渐渐地把那只牛围了起来。

7 jaws   

n.口部；嘴

参考例句：

• The antelope could not escape the crocodile's gaping jaws. 那只羚羊无法从鱷鱼张开的大口中逃脱。
• The scored jaws of a vise help it bite the work. 台钳上有刻痕的虎钳牙帮助它紧咬住工件。

8 coastal   

adj.海岸的，沿海的，沿岸的

参考例句：

• The ocean waves are slowly eating away the coastal rocks.大海的波浪慢慢地侵蚀着岸边的岩石。
• This country will fortify the coastal areas.该国将加强沿海地区的防御。

9 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

10 gulf   

n.海湾；深渊，鸿沟；分歧，隔阂

参考例句：

• The gulf between the two leaders cannot be bridged.两位领导人之间的鸿沟难以跨越。
• There is a gulf between the two cities.这两座城市间有个海湾。

11 standing   

n.持续，地位；adj.永久的，不动的，直立的，不流动的

参考例句：

• After the earthquake only a few houses were left standing.地震过后只有几幢房屋还立着。
• They're standing out against any change in the law.他们坚决反对对法律做任何修改。

12 cape   

n.海角，岬；披肩，短披风

参考例句：

• I long for a trip to the Cape of Good Hope.我渴望到好望角去旅行。
• She was wearing a cape over her dress.她在外套上披着一件披肩。

13 jewelry   

n.（jewllery）（总称）珠宝

参考例句：

• The burglars walked off with all my jewelry.夜盗偷走了我的全部珠宝。
• Jewelry and lace are mostly feminine belongings.珠宝和花边多数是女性用品。

14 killing   

n.巨额利润；突然赚大钱，发大财

参考例句：

• Investors are set to make a killing from the sell-off.投资者准备清仓以便大赚一笔。
• Last week my brother made a killing on Wall Street.上个周我兄弟在华尔街赚了一大笔。

15 fins   

[医]散热片；鱼鳍；飞边；鸭掌

参考例句：

• The level of TNF-α positively correlated with BMI,FPG,HbA1C,TG,FINS and IRI,but not with SBP and DBP. TNF-α水平与BMI、FPG、HbA1C、TG、FINS和IRI呈显著正相关，与SBP、DBP无相关。 来自互联网
• Fins are a feature specific to fish. 鱼鳍是鱼类特有的特征。 来自辞典例句

16 recognition   

n.承认，认可，认出，认识

参考例句：

• The place has changed beyond recognition.这地方变得认不出来了。
• A sudden smile of recognition flashed across his face.他脸上掠过一丝笑意，表示认识对方。

17 convention   

n.惯例，习俗，常规，会议，大会

参考例句：

• How many delegates have checked in at the convention?大会已有多少代表报到？
• He sets at naught every convention of society.他轻视所有的社会习俗。

18 species   

n.物种，种群

参考例句：

• Are we the only thinking species in the whole of creation?我们是万物中惟一有思想的物种吗？
• This species of bird now exists only in Africa.这种鸟现在只存在于非洲。

19 fauna   

n.(一个地区或时代的)所有动物，动物区系

参考例句：

• This National Park is an area with unique fauna and flora.该国家公园区域内具有独特的动物种群和植物种群。
• Fauna is a biological notion means all the animal life in a particular region or period. 动物群是一个生物学的概念，指的是一个特定时期或者地区的所有动物。

20 flora   

n.(某一地区的)植物群

参考例句：

• The subtropical island has a remarkably rich native flora.这个亚热带岛屿有相当丰富的乡土植物种类。
• All flora need water and light.一切草木都需要水和阳光。

21 cites   

引用( cite的第三人称单数 )； 传唤； 记起； [军事]传（或通）令嘉奖

参考例句：

• CITES is the Convention on International Trade in Endangered Species of Wild Fauna and Flora. CITES是关于濒危野生动植物种国际贸易的国际公约。
• Great bustard (Otis tarda) is listed as a first-rating protected bird in China and CITES II. 大鸨(Otistarda)是国家级保护动物，CITES附录物种。

22 delegates   

代表，代表团成员( delegate的名词复数 )

参考例句：

• The conference was attended by delegates from 56 countries. 此次会议有来自56个国家的代表出席。
• Delegates expressed strong opposition to the plans. 代表强烈反对这些计划。