How Is The Fish Rest?
Fish are very special animals that arouse many curiosities, especially in children. One of the most common questions is whether or not these species sleep in the depths of the water. Next, we will discuss how fish rest and how they can sleep underwater.
Do fish sleep?
All vertebrate or invertebrate animals, unicellular or multicellular, need a few hours of sleep to remain stable. Rest of the fish is essential to preserve the good health of your body and mind ; This makes it possible to reduce neuronal activity, make its tones shine and regain energy.
The great curiosity about the dream of fish is that these animals never close their eyes. This occurs thanks to an anatomical characteristic of fish, which is the absence of eyelids. The eyelids are an evolutionary adaptation of land animals, whose main function is to protect the eyes from dryness.
Fish do not need eyelids, as their eyes are always hydrated in a marine environment. Consequently, fish sleep with their eyes open and, at first glance, it appears that they are awake.
How is the rest of the fish?
Now that we know that fish need to sleep, it is a good time to ask ourselves what this rest period is like. As with humans, rest for fish consists of a significant reduction in physical and neuronal activity.
However, unlike human sleep, the rest of the fish does not reach the REM phase. That is, a fish will never sleep as deeply as a person because it never becomes totally unconscious while sleeping.
When a fish is sleeping, it stops swimming and only moves its fins very slightly to stay stable in the water: it remains in a state of rest. But by identifying any strange or abrupt stimuli in your environment, you will quickly react to be alert and run away.
As the fish is more vulnerable while resting, it usually hides between rocks or in a more hidden corner of the aquarium. In this way, it can go unnoticed by its predators and sleep safely.
In addition, some species have developed quite curious protection techniques to get a good night’s sleep. The parrotfish, for example, is capable of secreting a mucosa from its head that forms a kind of transparent cocoon around its body. This cocoon is believed to help hide its scent, thus misleading predators.
The shark’s dream
It is not difficult to perceive that sharks are quite particular species of fish, and their sleeping habits are also unique. Unlike the vast majority of fish, sharks are able to swim while they sleep.
Their ‘technique’ is to leave their mouths open to capture the maximum oxygen with the least effort while they continue swimming through the waters. The water is led to your gills, where oxygen is synthesized and then distributed to the tissues of your body through your blood.
When do fish sleep?
Another common question about fish sleep is whether it occurs at night, like humans, or does they maintain nocturnal habits and sleep during the day, like bats.
The truth is that each species of fish can maintain its own resting habits. Some fish are more diurnal and sleep at night, while others are more nocturnal and take advantage of the day to rest. This is also related to the natural habitat of each fish, the water temperature, the availability of sunlight, etc.
How do aquatic mammals sleep?
It is also common that we frequently wonder if the sleep of aquatic mammals is equal to the rest of fish. And the answer is negative.
Many aquatic mammals, such as whales and dolphins, are able to swim even when they are sleeping. Although they significantly reduce their physical and neuronal activity, these species rest while swimming.
These species, during sleep, only deactivate half of their brain, but thus they manage to considerably reduce energy expenditure. Of course, the part of the brain responsible for respiration must remain active because, otherwise, the animal would die.
As they are aquatic mammals, and not fish, they need to go to the surface to capture oxygen. For this reason, they cannot rest statically and neither do they become totally unconscious during their sleep.
