Why do fish swim in schools?

湖南华容二中 张明波

鱼儿在水里成群结队自由自在地游着。鱼儿为何喜欢群游？让我们一起揭秘吧！

Even though many schools are out for the summer,most fish tend to stick together and swim in schools wherever they may be.When fish stay together for social reasons,biologists say they are “shoaling （群聚）”.If they also swim together in the same direction,they are“schooling”.

So why do fish shoal and school together?The main reason appears to be that there's safety in numbers.Staying together in schools helps to protect fish from their enemies.While a predator（掠夺者）might easily catch a fish by itself,it's much harder for a predator to single out a victim if a fish is surrounded by hundreds of its closest friends.

Hanging out in schools also has a few other benefits. Scientists think that swimming close together may reduce friction （摩擦力）in the water and make it easier for fish to swim and conserve energy.When it's time to eat,it's also easier to find food as a group.A lone fish might be able to find a meal on its own,but having hundreds of sets of eyes and noses on the prowl for food is even better.

How many fish does it take to be a school?While there's no magic number that equals a school,there would usually need to be at least five or more fish to be considered as a school.In the wild,though,fish schools can be huge.In large bodies of water,schools of fish numbering in the hundreds or even thousands are not uncommon.

If you've ever seen a huge school of fish swimming together,you may have wondered how they keep from swimming into each other.Scientists believe fish use a combination of all of their senses to keep track of the movements of the fish around them.Having eyes on the sides of their heads helps fish easily to see what's going on around them.Sight isn't the only tool fish use,though.They also use hearing and even their sense of smell to stay with the group.

阅读检测

1.What do we know about shoaling according to biologists?

A.It has the same meaning as schooling.

B.It is actually different from schooling.

C.It means fish swim to the same place.

D.It suggests fish swim for different reasons.

2.Which might be the reason for fish swimming in schools?

A.They can kill the predators.

B.They can swim very far.

C.They can find food easily.

D.They can become tired easily.

3.What can help fish to swim in schools peacefully?

A.Touch,hearing and taste.

B.Hearing,smell and sight.

C.Sight,water and light.

D.Taste,smell and hearing.

语言学习

写作推荐

Staying together in schools helps to protect fish from their enemies.群聚可以帮助鱼儿免受敌人的袭击。

【信息提取】protect...from...意为“免受……伤害”。

【句式仿写】为了免受风吹，冬天她通常待在家里。