Why do fish keep their eyes open forever? Why do fish sleep with their eyes open

Because: fish eyes do not have eyelids, so they also sleep with their eyes open. Even when he dies, he doesn't close his eyes.

Although fish belong to the lower vertebrates, the structure of their eyes is similar to that of the human eye. The difference is that the lens of the human eye is oblate and round, allowing you to see things in the distance; The lens of the fish's eye, on the other hand, is spherical in shape, and only close objects can be seen. All fish are short-sighted, and they rarely see objects up to 12 meters away, which is related to the fact that the curvature of their lenses cannot be changed.

However, although the fish is short-sighted, they are very responsive. Anglers often find that when he walks to the river and has no time to put down the hook, the fish has already noticed it and quickly escaped.

It turns out that although the fish does not see far in the water, it is able to see objects on land in the water through the refraction of light. As a result of refraction, the fish perceives objects on land to be much closer and higher than they actually are, so that before the person is near the water's edge, it feels that the person is above its head. Therefore, experienced anglers usually squat on the shore so that the human body is at a minimum angle to the water level, so that the fish cannot see the person.

In general, fish have a much wider field of view than humans, so they can see objects in front of and behind and above without turning around, for example, freshwater salmon have a field of view of 150 degrees in the vertical plane and 160 170 degrees in the horizontal plane, while the human eye has a field of view of 134 degrees and 154 degrees, respectively. It is for this reason that the ultra-wide-angle lens used on the camera is also known as a fisheye lens.

It has no eyelids because the fish does not have eyelids (eyelids) and cannot close their eyes, so the fish always have their eyes open.

Lazy people will say that blinking is too tiring.

Pessimistic people say that they will never be able to open their eyes again.

Objective people say that fish don't have eyelids.

Optimistic people say that fish are not like missing out on every wonderful piece around them.

Vigilant people say that fish should be on high alert haha.

Fish sleep with their eyes open because they have no eyelids and cannot close their eyes when sleeping.

Fish live in the water for a long time, and due to the low light in the water, the fish's eyes become short-sighted, and they cannot judge the surrounding things through their eyes. Therefore, when the fish sleep, they stop the body organs to achieve the effect of sleeping and resting. When the fish swims sideways, floats up, or swings their tails, they are likely to be sleeping, and this is how the fish can rest themselves.

Sleeping properties of fish

1. Hide in the dark: Because fish may be attacked by predators when they sleep, they often choose some relatively safe places to hide, such as goldfish when sleeping, often near stones or aquatic plants. There are also some benthic fish that can hide themselves in the sand at the bottom of the water.

2. Secrete bubbles: In order to protect themselves while sleeping, some fish will secrete a gelatinous substance and wrap themselves in it. Don't worry about bubbles suffocating themselves because it will leave a hole in the mouth for water exchange and breathing.

3. Sleep while swimming: Some fish in the ocean have a relatively high metabolism and must always keep swimming, so they will not stop when they are sleeping. For example, sharks, tuna, etc., they also swim while sleeping, so it is difficult to tell whether they are awake or not.

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

Take a look at the following and you'll understand:

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.

Fish do not have eyelids, fish do not blink their eyes, fish breathe with gills and can absorb the rich oxygen in the water, while humans are different, this is due to biological evolution and environment.

<> fish do not have eyelids, so their eyes are always open. The reason why there are no eyelids is because this animal lives in water, and the eyelids do not play much of a helpful role, and there is enough water in itself to moisten the eyes, so there is no need for eyelids. Although the fish's eyes are always open, it does not mean that it will not sleep, and if it stays in one place for a long time, it may be resting.

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Hello, fish don't have eyelids, so they can't close their eyes. It looks as if it never sleeps. Most of the fish sleep in a quiet state of immobility.

Just as people sleep, this is how fish can rest their bodies. Almost every fish is sometimes in some kind of energy-conserved state, which we can call resting, or even "sleeping", although this behavior may not be the same as the "sleeping" of most land animals. Many fish, such as sea bass, sleep at night on top of or under logs.

Polyps are active during the day and take refuge in the cracks of the reef at night. The appearance of fish at rest is very different from other times. For example, many small carp that gather together during the day and are very active during the day scatter at night, leaving them motionless in the shallow water.

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Some fish don't have eyes, and some don't move their eyes.