Why the fish does not close eyes
Fish, like other representatives of the fauna are sleeping. Only they do not close their eyes. That's because the fish simply does not age. This is unlike humans and terrestrial fauna due to the environment in which they live. People constantly have to moisturize the outer layer of the eye, blinking. In the dream to do it quite difficult, so ever tightly cover the cornea and safeguard it from drying out. Fish live in water, which gives them eye to dry. Additional protection it is not required.
Ever there are only some sharks. While attacking a predator zazhmurivaetsya, thereby protecting the eye from damage. Sharks have no eyelids, roll your eyes.
How do you sleep bony fish
Aquarists are sometimes unable to watch their Pets go on the ground or algae, freeze belly up or perpendicular to the bottom. However, it is necessary to make a sudden movement or turn on a light, as Pets are once again beginning to swim as if nothing had happened. Sleep all the fish are very sensitive. Most species choose to sleep in a quiet place, but everyone has their habits. For example, cod can lie down sideways on the bottom, herring – hang in the water head down, flounder is to burrow into the sand. Bright tropical parrot fish – great original. Getting ready for bed, she builds around herself a cocoon of mucus, which, apparently, does not allow predators to detect her scent.
All kinds of fish, depending on the time of their activity can be divided into day and night.
How to sleep cartilaginous fish
The structure of bone and cartilaginous fish differ. Cartilaginous fish, which include sharks and rays, do not have caps on the gills, and the water is supplied only during the movement. To sleep they did not work. However, in the course of evolution they managed to adapt and to grab yourself a watch for travelers. Some types of acquired bryzgalina special organs behind the eyes, in which fish draw water and send it to the gills. Others prefer to choose a place to sleep with a strong bottom current or sleep, constantly opening and closing the mouth, thereby allowing the water to saturate the blood with oxygen.
Shark Katran, living in the Black sea, and even falling asleep. For the movement it meets the spinal cord, head at this time can rest. Also scientists believe that some members of the cartilaginous fish can sleep in the manner of dolphins, follow the steps in "disabling" right and left hemisphere.