Some spermatozoa get into an opening of a surface of caviar, but only one of them gets to an ovum since at it now under a cover the additional membrane is formed and to other spermotozrida the way is closed. After man's and female kernels merge, reproduction of cages and formation of an embryo which starts feeding on a yolk at this time begins. It gradually has a spinal cord, the head, branchiate cracks and other bodies and, at last, he leaves a cover together with the rest of a yolk on which the larva feeds still some time, and then starts floating and looking for a forage.
Epidermis consists of several layers of cages among which there are cages developing the special mucous allocations acting on a surface of skin and doing it smooth and slippery that reduces water resistance at the movement of fish. This mucous layer is constantly updated and interferes with the settlement and development of various mushrooms and bacteria.
The digestive tract consists of an oral opening, a mouth, a pharyngeal cavity, a gullet, a stomach (is absent at Karpov), intestines, a rectum and the additional bodies participating in digestion of food. In a mouth, in most cases, there are teeth which after wear are often updated. The pharyngeal cavity is cut through by branchiate cracks, and branchiate stamens interfere with an exit of food through them outside. Then the short and narrow gullet passing into a stomach which is connected to intestines follows. At carnivorous fishes it short, at herbivorous - long and is spiralno curtailed. In all digestive tract there are mucous glands. Near intestines the liver and a pancreas are located large, fat-rich and vitamins. These three bodies digest food, i.e. decompose it to the elementary components, and then acquire. The undigested remains go to a rectum and come to light through an anus.
The majority of species of fish have the swimming bubble filled with mix of gases pustotelny body, which arose in development of an embryo from an intestines wall. At one species of fish communication between them remains, at others is liquidated. The swimming bubble provides equilibrium position of a body in water and fish, regulating amount of gases in it can emerge, plunge or soar in water. Whitebaits of some species of fish are compelled to take air and to fill with it a swimming bubble to rise to a water surface as soon as will start floating. If water level is high, they will not be able to make it and remain cripples.
The body of the fishes who are directly living on soil is usually squeezed from top to down, and the belly is strongly flattened. Pair fins are shifted in the parties, and chest are strongly developed and can serve for movement on soil.
Eyes are located on both sides of the head that provides a big field of sight, though has shortcomings of monocular sight - absence of feeling of prospect and a bad note of distance. But, ahead there is a site which is available to both eyes of fish and she if necessary is better to estimate distance turns towards the subject interesting her. At the majority of fishes of an eye are located from head sides, closer to the end of a snout than to gills. At the fishes leading a benthonic life they are located in the top part of the head. The distance between eyes measured on head top is called as forehead width.