環(huán)球英語—1039:Deep-Sea Discovery

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Welcome to Spotlight. I’m Liz Waid.
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And I’m Robin Basselin. Spotlight uses a special English method of broadcasting. It is easier for people to understand, no matter where in the world they live.
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“Over 60% of our planet is covered by water more than a mile deep. The deep sea is the largest living space for animals. And it is largely unexplored. More people have travelled into space than have travelled to the deep ocean.”
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These words are from a film by the BBC. This film was part of a series that explored the world’s oceans. Many people know something about the top layer of the ocean - where the water and land meet. They know the plants and animals that live in this area. These animals and plants use the light from the sun to grow and live.
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But as the sea gets deeper, the light disappears. This is the deep-sea. At about 1,000 meters under the sea, there is no more sunlight. In fact, in some places the sea is as deep as 11,000 meters. So what exists between 1,000 meters under the sea and 11,000 meters under the sea? Is there life? How could anything survive without light? These are just some of the questions deep-sea researchers aim to answer.
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Today’s Spotlight is on two researchers who explored the deep-sea. Their discovery changed how many scientists think about life on earth.
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Kathy Crane and Jack Corliss are scientists. In 1977 they set out to answer some questions about the ocean. They began by visiting a place in the Pacific Ocean. It is called the Galapagos Rift. It is near the coast of Ecuador, in South America.
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Crane and Corliss used a sea vehicle called Alvin. Alvin was about eight meters long. And it could travel into the deep-sea - down to about 4,000 meters. Corliss rode on Alvin with two other researchers.
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Kathy Crane stayed on the mother ship. This ship stayed above the surface. It helped control Alvin’s movements. It could also see through cameras what the crew on Alvin could see.
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The group’s goal was to visit a hydrothermal vent at the bottom of the Galapagos Rift. Hydrothermal vents are openings at the bottom of the sea floor. They push out hot water and other substances, like chemicals, from deep in the earth. Crane and Corliss hoped to learn more about the sea from these vents.
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The trip to the bottom of the ocean took about three hours. Alvin travelled deeper and deeper into the ocean. The light in the water began to disappear. Crane and Corliss talked to NPR reporters Christopher Joyce and Rebecca Davis about their trip. Corliss told them:
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“After we left the surface, we were going down to a different world. If you put your face to the window you would see a short flash of light go by. There were organisms in the water that were bioluminescent. They would turn on their lights.”
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Finally, Alvin arrived at the hydrothermal vent. Crane and Corliss were shocked by what they saw. Life! There were living creatures around the vent - like clams, mussels, crabs and worms. For Crane and Corliss, this was a beautiful sight. Crane told NPR:
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“It was surprising. Just beautiful, blue-colored water and animals moving slowly. They were just drifting in this peaceful water.
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But the most amazing thing they saw that day was a long thin worm. Each worm was connected at one end to a place near the opening of the hydrothermal vent. Some were over two meters long. And at the end of each worm was a bright red plume that looked like a small cloud. Corliss was amazed by these worms. No one had ever seen anything like these before.
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“They looked like white tubes. They had these beautiful red plumes - like a large feather from a bird. The plumes were bright red, moving around, rolling and falling. It was amazing.”
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For many years, scientists believed that the light from the sun was very important for life. In fact, they believed it was necessary. So, how did these creatures survive near the hydrothermal vents under the sea? The scientists wanted to study these amazing animals. They used Alvin’s mechanical arm to gather some examples of these animals.
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After Alvin returned to land, the scientists had a new question. They wanted to find out what this new kind of worm was. How did it survive without sunlight? They sent the worm they had collected to Doctor Meredith Jones. Doctor Jones worked at the Smithsonian’s National Museum of Natural History in the United States. He was an expert on animals like this worm.
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Doctor Jones discovered three amazing things about this worm. First, this worm was a new animal that no scientist had ever studied before. Doctor Jones named it Riftia pachyptila. The second amazing thing about this worm, Riftia, was its huge size. Normally, worms living in the deep-sea are much smaller. They are usually less than two and a half centimeters long. But Riftia was six feet long - about one point eight meters. And it was about two and a half centimeters wide. But the third discovery was the most amazing. It seemed like Riftia did not have any mouth to eat!
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Scientists discovered that Riftia does not have a system inside its body to digest, or process its own food. Instead, the worm gets the food it needs from the hydrothermal vent, and a group of bacteria.
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Riftia always lives near a hydrothermal vent. The vent pushes out chemicals like hydrogen sulfite. For many living creatures, this chemical is a poison. It also smells very bad - like old bad eggs. Riftia takes in this chemical through its bright red plume. A group of bacteria lives inside Riftia. The bacteria eat the hydrogen sulfite. Then, they produce carbon compounds. Riftia uses this carbon for energy - like food. This process is called chemosynthesis. Scientists believe this is one of the greatest scientific discoveries of the last 100 years.
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Scientists also visited other hydrothermal vents near this vent. Near these other vents, they also found many other interesting creatures. And many of these creatures only live here - and nowhere else in the world.
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Crane and Corliss made these important discoveries more than 30 years ago. But scientists still wonder about what other discoveries the ocean holds. What other creatures already exist here on earth that people have not yet discovered? Scientists will continue to search and study.
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The writer and producer of this program was Liz Waid. All quotes were adapted for this program and voiced by Spotlight. You can listen to this program again on the internet at https://www.radioenglish.net This .program is called, “Deep-Sea Discovery”.
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We hope you can join us again for the next Spotlight program. Goodbye.