Listen to part of a lecture in a marine biology class.
So we've talked a little about how fish use senses like vision, touch and so forth, but what I want to talk about now is a special ability some fish have. The ability to produce electricity in their bodies. You are probably familiar with these fish, these fish that send out electric currents from their bodies naturally.
So what's the purpose of this? Well, as you might expect, it can serve some important roles in helping fish survive.
First, fish, like all animals, need food to survive. Well, the ability to produce electricity helps some fish to capture prey, you know, other organisms in the water that they eat. Take the electric eel for example. The eel produces a strong electric current in its body. When the eel comes into contact with one of the smaller fish it depends on for food, the electric current that it sends out shocks the smaller fish and paralyzes it. It's not able to get away from the eel. The eel captures the fish easily and can eat it at its leisure. So this ability to use electricity to capture prey ensures that the eel gets the food it needs to survive.
The ability to produce electricity also helps fish to successfully navigate their environment by detecting nearby objects. Some fish have poorly developed eyes. And the water they live in can be muddy and dark. Now, there's a fish called the knife fish that produces electricity. This creates an electric field around the knife fish's body. When the knife fish swims close to, say a rock, it sends a disturbance, urn, an interference in its electric field.
The fish then realizes that there's a rock nearby and that it has to avoid crashing into it. Once this happens, the knife fish swims away from the rock and thus avoids harming itself.
Using the examples of the electric eel and the knifefish, explain how producing electricity benefits certain fish.
名师1对1，深度分析薄弱项，高效提分
In the lecture, the professor talks about a special ability that fish has to produce electricity in their bodies. First, the ability to produce electricity helps some fish to capture prey. Take the electric eel for example. It can produce a strong electric current in its body. When it comes into contact with the smaller fish it depends on for food, it sends out electric current which shocks the smaller fish and paralyzes it. Second, the ability to produce electricity also helps fish to successfully navigate their environment by detecting nearby objects. Take knifefish for example. The fish creates an electric field around its body. When the knifefish swims close to a rock, it sends a disturbance. Then the fish realizes the rock nearby and avoid crashing into it.
