任务六 阅读与回答问题
If you have no central brain, can you learn how to see and avoid bumping into things? Researchers have found that for jellyfish, this is no problem at all, said Smithsonian Magazine.
In the waters of the Caribbean, jellyfish avoid bumping into the roots of mangroves. The roots could hurt them, but the jellyfish carefully avoid them even when the water is not clear. So how do they do it?
Although they have no central brain, the jellyfish do have a nervous system. It’s made of four main parts that look like hanging ropes. Each part has about 1,000 neurons(神经元)and six “simple” eyes. They let them see and avoid things and also help them find food. They even do this in dirty water that is hard to see. “They need to learn this,” biologist Anders Garm said. “They have to learn, ‘How is today’s water quality? How is the contrast(明暗对比)changing today?’”
Garm and other scientists did a test to get the result. They put some jellyfish in a tank and lined the outside with stripes that looked like the mangroves. They found the jellyfish learnt in eight minutes not to bump into the tank. When there were no stripes, the jellyfish kept bumping into the tank. “This was because there was no visual cue(视觉提示). So they didn’t learn anything,” Jan Bielecki, one of the study’s writers, explained. The result shows that the jellyfish can do associative learning and have short-term memory.
The findings may help scientists know the evolution(演变)of learning as scientists recently found a 508-million-year-old fossil(化石)of a jellyfish, reported Smithsonian Magazine.
回答下面5个问题,1~4小题每题答案不超过6个词。
1. Why do jellyfish carefully avoid bumping into the roots of mangroves?
Because the roots can hurt them.
2. How many main parts does jellyfish’s nervous system have?
Four.
3. How did scientists get the result that jellyfish learn to see and avoid things?
By doing a test.
4. What happened when there were no stripes outside the tank for jellyfish?
They kept bumping into the tank.
5. What do you think of jellyfish?(请自拟一句话作答)
They are clever.（言之有理即可）
