Teacher Wang Qian of Huzhu Road Primary School 33 Today s homework writes why fish sleep with their

Fish do not have eyelids, so they keep their eyes open. But they also have sleep.

Sleep in fish.

Many people mistakenly believe that fish are animals that don't need to sleep, mainly because of misconceptions. In fact, all vertebrates need rest in order to recover from fatigue in the central nervous system and limbs. As a member of the vertebrates, how can fish be an exception?

They also require sleep rest. So, why do fish give us such an illusion that we don't sleep? We already know that fish, unlike people, does not have real eyelids, therefore.

The fish can't close their eyes whether they are asleep or awake, and even when the fish dies, their eyes are wide open, and they "don't blink to death". In addition, when the fish is resting, it does not need to lie down like other animals, it only needs to be still or slightly swinging in the water.

Some fish sleep in a particularly interesting position. There is a parrotfish that sleeps on the bottom of the sea; Blackfish bury their bodies in the sand and lie on their sides; The river [t] also bends its body to sleep, but it uses water or stones as a backrest. During the day, its body is brown and dark green, but when it sleeps it turns light gray, and its fins and tail are mostly black.

This is because the river [t] sleeps among rocks and aquatic plants, and this posture and the change in body color while sleeping can give itself "cover" against the detection of predators. The fish sleeps alternately by alternating the two cerebral hemispheres, usually always in a state of sleep and the other awake, and every ten minutes, there is a rhythmic alternation. So, on the surface, it looks like it never has to sleep.

Some fish because of the relationship of living environment, can not find a suitable "bed", so can not sleep well, especially in the deep sea or the ocean for long-distance migration of pelagic fish, due to the depth of hundreds of meters to thousands of meters, so that even if the fish want to lie down to rest, but because the pressure is too great, can not settle casually, can only take the method of floating in the water to rest.

Fish float in the water to rest, appropriately stop the activities of various organs, or make a slight movement, which is called "sleep swimming" in fish physiology. The sleeping and swimming of fish varies, and some are in order to defend against the invasion of predators, and often gather into large groups; Others disperse in a certain range of activities, and then regroup at dawn the next day and continue to migrate forward.

This habit of fish is a great inspiration for fishermen. According to the habits of the fish's sleep, the clever fisherman sinks the old tires and wooden boats to the bottom of the sea at the fish-infested places along the coast or near the harbor, creating a quiet "bedroom" that is conducive to the fish's rest, so that the fish "throw themselves into the net" and gather here in groups for round-up. This kind of artificial "hotel" and "guest house" for fish is called "artificial reef" in foreign countries.

Because the fish has no eyelids, they have to sleep with their eyes open (but imagine first, then there is later, and then know the problem.)

The fish sleeps with its eyes open because it does not have eyelids (i.e., eyelids).

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