Hydras are a special family that is part of the class of hydroid polyps, a type of intestinal. They live only in freshwater bodies of water, mainly covered by duckweed. They prefer to settle in the brightest places of ponds and swamps, as they like sunlight. They feed on water fleas, small mosquito larvae, fry, cyclops, and pond plankton.
Polyp hydra is similar in size to barley grain. It is translucent, grayish in color. On the one hand, it has a hole that acts as a mouth and is designed to extract waste products, surrounded by tentacles. On the other hand, there is a so-called sole, with the help of which it is attached to a surface motionless in water.
The body consists of two types of cells - external and internal. The entire inside is just the intestinal cavity. Breathing is carried out by the entire surface of the body.
Once in a stable position, the freshwater hydra freezes in anticipation of the victim. There are small cilia on the tentacles to help identify the approaching prey. On the surface of the hydra's body, mostly on the tentacles, there are cells with a protruding hair containing a capsule with poison. When prey comes into contact with such a cell, the released poison kills it. Hydra tentacles pushes prey to the oral cavity and swallows it.
Polyp Hydra is a real glutton. He is able to eat a volume of food three times his own. Swallowed food immediately enters the intestinal cavity, where it is quickly digested.
If two hydras claim for one prey, then they begin to suck the victim from two sides. On contact, a larger, stronger, swallows a smaller one. But the paradox, the swallowed hydra does not die. After some time, it is erupted from the inside swallowed. Having been in the intestinal cavity of a relative, "brushing herself off", she finds a convenient place, sticks in and freezes in anticipation of food.
Freshwater hydra can breed in two ways: budding (asexual) and division (sexual). In the first method, one or several growths are formed on her body, which, having matured, are separated from the "mother". In a month, the hydra is able to create up to 15 similar individuals. This simple method is quite productive, since most of the children thus obtained survive.
The second breeding option is used in case of lack of food. In conditions of malnutrition, the formation of germ cells occurs. Moreover, on some individuals male cells are formed, and on others - female cells. After fertilization, an egg is formed, the adult individual dies while the formed egg sinks to the bottom of the reservoir. After lying for a while, hydra can form from it in the spring, but more often it dies.
The freshwater hydra polyp is immobile for most of its life. If necessary, he can move, bending the body and moving the sole. Having found a new haven, it sticks in.
Polyp Hydra is characterized by its high ability to repair damaged or lost parts of the body (regenerate). When one individual is cut into two parts, even unequal, two hydras become. Scientists have proven that theoretically hydra are immortal.
