大千世界:電魚

所屬教程:大千世界

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Don: Zzzzap! zzzzaapp!

Yaël: What are you doing, Don?

D: Yaël, I'm pretending I'm an electric fish having a conversation.

Y: Like an electric eel?

D: The so-called electric eel is one kind of fish that produces electrical discharges. They can emit very strong electrical charges, hundreds of volts stronger than a car battery! They use their electricity to shock and kill prey or deter predators. But there are hundreds of other fish species that produce relatively weak electrical discharges–much too weak to hurt or shock you or another fish.

Y: Why? Such weak electric signals don't seem very useful?

D: Weakly electric fish use their electric organ discharges for two important functions–communication and navigation. Since many electric fish are nocturnal or live in murky water, they have evolved the ability to "see" their surroundings using electricity. The electrical field they create reacts differently to different kinds of objects. For example, a rock, a fish and a plant each conduct electricity differently. The fish detect these differences using electric receptors in their skin, and so can move easily around obstacles and find food without using their eyes. The dark or murky water also makes it hard to find and communicate with others. But electric fish use their electrical discharges to send signals to one another. By varying the frequency or pattern of their electric organ discharges, these fish can create complex communication signals. Behavioral studies of electric communication in these fish have found that electric fish signal this way during courtship, territorial disputes and other social situations.

Y: Cool! So Electric fish use electricity instead of light and sound to find their way and talk to each other!

Discharge: 排放(物)

thunder and lightning caused by electrical discharges 由放電長生的雷電

emit: 散發(fā),放射;發(fā)出

The chimney emitted thick smoke into the air.

煙囪向空中散發(fā)出濃煙。

Predator: 食肉動物;掠奪者,捕食者

Nocturnal: 夜間活動的

The owl is a nocturnal bird.

貓頭鷹是夜間活動的鳥。

Murky: dark and difficult to see through 渾濁的，污濁的

She gazed into the murky depths of the water.