How does the fish sleep?
What we mean by Fish Sleep
Sleep is a natural phenomenon that living things go through, including humans. And it aims to get rid of the pain and pressures that beings are exposed to during the day, and the brain in some stages of sleep experiences a state of hyperactivity, so it rearranges and organizes events and experiences that a person goes through throughout the day, in contrast to the common belief that the brain stops its activity during sleep, despite the fact that lack of clarity of the reasons why sleep is a vital necessity, but we know that it must sleep to be able to continue to live, and I said to lead to the feeling of apathy and confusion, and the deprivation of it in the long term he may significant impact on the human psyche, and is similar to the effect of poisoning; Therefore, sleep deprivation has been used as a form of torture throughout history, and to understand the importance of sleep for living organisms.In general, it suffices to know that laboratory rats, which have an average age of three years, will die if they are deprived of sleep for three weeks.
The need for sleep of living things varies; In terms of duration and pattern from one species to another, sleep is known as a period in which the organism experiences a decrease in physical activity and less response to stimuli, and in advanced animals such as mammals, it can be known that the animal sleeps from closed eyes, During sleep. The method of sleeping differs from one organism to another, for example humans lie on the bed to sleep, while horses, elephants, and giraffes sleep in a standing position, while the bat sleeps while it is suspended from its legs with its head down, and whales sleepAnd dolphins in a unique way; Where half of its brain sleeps while the other half remains awake, as for the length of time that animals spend in sleep, it also varies from one species to another. The giraffe needs thirty minutes of deep sleep divided into separate sleep periods, while the brown bat needs to sleep for about twenty hours per day, and the sleep pattern of young animals differs from the adult animals of the same type; For example, mammals' need for sleep diminishes as they transition from childhood to adulthood, while baby killer whales and bottlenose dolphins do not seem to sleep during the first few months of their lives.
How do fish sleep
It is difficult to apply the usual standards when studying the sleep behavior of fish , as they do not have complex brain structures that can measure the change in their electrical activity when asleep, and they do not have eyelids that can be closed, on the other hand there are other phenomena that indicate that the fish are asleep, such as: inactivity for a long time Or her being in a comfortable position often in a shelter, or her low response to normal stimuli. Research indicates that fish experience a state of loss of consciousness that is somewhat similar to sleep in humans, so their activity decreases and their metabolism decreases while they remain alert to the dangers surrounding them, some fish are floating in the meantime, and some of them They may hide in mud or coral reefs.
It is a mistake to think that all types of fish are capable of falling asleep; There are types of fish that do not sleep, including the blue fish, which are fish that swim in water day and night, and although their speed at night is less than usual, they remain Vigilance and respond to various stimuli, just as some types of shark cannot sleep, but must remain in constant motion; This is to maintain the flow of water to their gills so they can breathe, And some types of fish do not sleep to prevent it from being washed away with the current. Some types of fish do not sleep in specific situations, such as: the Mozambican tilapia fish, which does not sleep before reaching adulthood, and some fish do not sleep during the seasonal migration period, and some do not sleep during the stage of spawning, and there are fish that do not sleep while caring for their young.
Sleep patterns of different types of fish
The following are some of the sleep patterns that scientists studied for fish living in artificial aquariums:
The Mozambique tilapia
scientifically known as (Oreochromis mossambicus), rests under the water basin when sleeping and its breathing rate decreases, and the eyes stop moving, and the fish do not appear in response to food or when exposed to a stimulus.
Brown bullheads
known scientifically as Ameiurus nebulosus, sleep lying down with their fins extending on the bottom of the pelvis, and their cardiac and respiratory activity decreases more than usual, and does not respond to stimuli such as sound or touch.
The zebrafish
sleeps during the night floating horizontally, or it may float with the head slightly elevated above the level of the body, and the movement of the mouth and gills is reduced by half, and it becomes difficult to alert, and when the fish are deprived of this type of sleep, they have sleep attacks. After a longer period, and its ability to respond to stimuli is reduced more than usual, which is known as the rebound effect.
Oscar fish
remain calm at night at the bottom of the pond, with their eyes facing downward, and do not respond to stimuli, and on the other hand there are other fish belonging to the family of cichlids to which the Oscars belong. They can sleep near the bottom or up in Water column.
Some types of tilapia stop moving, and their pelvic fins decrease towards the bottom when sleeping, but they sometimes activate and begin to move with their pelvic fins facing upwards, and examples of this type of fish are:
Rainbow cichlids, and confit cichlids. Some types of fish sleep while hiding in holes and crevices, or among plants and coral reefs, or inside sponges, or bury themselves in the sand.
The parrotfish and the wrasse fishes secrete a mucous coat that envelops themselves, or closes the door of their shelter in order to be able to sleep and protect themselves from external parasites and predatory fish. This is because the mucus blocks the smell of the fish and makes it difficult to discover where it sleeps.
