Many animals in nature and at home relax in different ways. Some are standing, some are lying or sitting asleep, some are afloat. For example, have you thought about how the fish sleeps? These cold-blooded also need rest, even for a short time. An interesting question, agree, because no one has ever observed fish with their eyes closed. Why? Yes, because they have no eyelids, and they just have nothing to close them!
Terrestrial animals are forced to moisturize, constantly blinking, the eye surface. But in a dream it is quite difficult to implement, since control over the reactions is lost. Therefore, the eyes of mammals, for example, have been closed for centuries by sleeping. Fish have a different story: they exist in water, so there is no need to constantly moisturize the eyeball . But still they, like all animals, are forced to rest. We will talk about how the fish sleeps in our article. And these representatives of the fauna world sleep in different ways, which depends on the species and habitat.
How the fish sleeps
It is known that fish do not rest the way mammals do, for example (it’s good, by the way, to study the behavior of these animals for those who have an aquarium). The sleep of fish, rather, resembles the phase of rest, relaxation, when many body functions slow down, and the reaction weakens. Some species of fish so turn off their reactions that they can literally be touched by hands and shine a flashlight in the eyes - they still remain immobilized. Some species, in contrast, in this state may well sense danger.
Where do the fish sleep?
During their vacation, many species of these cold-blooded become almost motionless. They, as a rule, rest in the near-bottom territory. This applies to many large river and lake species. But the assertion that every fish sleeps at the bottom will not be entirely true. Some oceanic fish species must constantly be in motion, even during sleep. These include, for example, sharks and tuna. Water must constantly pass through their gills, otherwise they may suffocate. Therefore, tuna lie on the water against the tide and, thus, swimming, resting. And the sharks - these contemporaries of dinosaurs - do not have a bubble at all, which other fish species have. This fact is another argument to be in motion even during rest. Indeed, otherwise the shark will simply sink to the bottom and, in the end, no matter how ridiculous it sounds, will drown! And yet - skates and sharks do not have lids on the gills, like many bone fish, so water enters there only when the fish is moving, and it’s not possible to sleep relatively quietly, as the bones do, it’s necessary all the time to swim somewhere.
Features of rest
The position in which the fish sleep is largely dependent on the species. For example, an astronotus hangs upside down. A clown fish at the bottom of the aquarium is laid on its side. Some aquarium fish just hang still.
How does the fish sleep? In natural conditions, the provisions for her relaxation can also be very different. Flounder digs into the sandy soil at the bottom. Cod sleeps lying down. Herring is still upside down, rafting downstream. Most near-bottom fish sleep in secluded places, previously prepared among stones and crevices, corals and algae. And the parrot fish envelops itself in a cocoon of mucus to become invisible to the predator.
Duration
How many fish sleep? Most fish, like many animals, are active throughout the daylight hours. With the onset of darkness, life freezes, the time for rest. Therefore, for example, it is so important for fish contained in aquariums, the reasonable observance of their natural regime. Agree, if you wake up at three in the morning with bright light and noise, you are unlikely to be able to like it. So it is for fish: you need to turn off the artificial lighting of the aquarium in the evening and at night, so that the animals can relax. Otherwise, the life expectancy of aquarium fish can be significantly reduced.
Night hunters and not sleeping
It is characteristic that some river predatory fish (for example, catfish or burbot) do not sleep at night. They prefer to hunt, and during the day - to relax. However, among the fish, leading a daily lifestyle, there are those who like to arrange a siesta in the middle of the day. But dolphins (mammals, which were previously classified as fish) never sleep at all! The hemispheres - left and right - of the dolphin's brain rest alternately (each about 6 hours). The rest of the time, both hemispheres are awake.