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第1段
1 .<-NARRATOR:-> Listen to part of a lecture in a marine biology class.
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第2段
1 .<-FEMALE PROFESSOR:-> So, we've talked a little about how fish use senses like vision, touch, and so forth...
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2 .but what I wanna talk about now is a special ability some fish have,
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3 .the ability to produce electricity in their bodies.
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4 .You're probably familiar with these fish, these fish that send out electric currents from their bodies... naturally.
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5 .So, what's the purpose of this?
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6 .Well, as you might expect, it can serve some important roles in helping fish survive.
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第3段
1 .First, fish, like all animals, need food to survive.
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2 .Well, the ability to produce electricity helps some fish to capture prey . . .
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3 .you know, other organisms in the water that they eat.
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4 .Take the electric eel, for example.
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5 .The eel produces a strong electric current in its body.
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6 .When the eel comes into contact with one of the smaller fish it depends on for food,
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7 .the electric current that it sends out shocks the smaller fish and paralyzes it...
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8 .it is not able to get away from the eel.
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9 .The eel captures the fish easily and can eat it at its leisure.
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10 .So this ability to use electricity to capture prey
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11 .ensures that the eel gets the food it needs to survive.
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第4段
1 .The ability to produce electricity also helps fish to successfully navigate their environment by detecting nearby objects.
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2 .Some fish have poorly developed eyes, and the water they live in can be muddy and dark.
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3 .Now there's a fish called
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4 .the knife fish
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5 .that produces electricity.
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6 .This creates an electric field around the knife fish's body.
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7 .When the knifefish swims close to, say, a rock,
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8 .it senses a disturbance... uh... interference in its electric field.
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9 .The fish then realizes that there is a rock nearby and that it has to avoid crashing into it.
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10 .Once this happens, the knifefish swims away from the rock and thus avoids harming itself.
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