The freshwater hydra - a typical representative of coelenterates animals living in lakes, ponds, creeks and rivers.
The first saw and described the hydra A. Leeuwenhoek, the inventor of the microscope and the famous naturalist.
The structure of the freshwater hydra
This freshwater polyp looks like a short,gelatinous and translucent tube the size of a grain surrounded by crown of tentacles 6-12. At the front end of the body is the mouth, the rear end of hydra tapers into a long leg with a sole at the end. The full hydra has a length of about 5 mm, much longer hungry.
Nutrition and lifestyle
The freshwater hydra eats cyclops, daphnia,mosquito larvae and fish fry. It is attached to the sole of the plants and slowly swinging, sliding long tentacles in all directions, looking for prey. The tentacles are covered with cilia sensitive to the touch which is thrown stinging thread, paralyzing the victim.
Production pulled to the oral tentacleopening and absorbed. Digested swallowed, Hydra throws digestion residues through the same hole. If successful hunt this little predator can consume enormous amounts of food several times its volume. With a translucent body, Hydra takes the color of the food eaten and can be red, green or black.
Reproduction of freshwater hydra
With good nutrition freshwater hydra quicklybegins to bud (asexual reproduction). Buds grow from a small hillock to the fully formed individuals for several days. At first the young hydra connected to the mother's body, but after the formation of the sole are separated and begin an independent life. Kidney hydra is usually in the summer.
In cold weather or in adverse conditions(Hunger) hydra reproduce eggs formed in the outer layer of the body. The mature egg is covered with a sturdy shell and falls to the bottom of the reservoir. After the formation of egg old individuals usually die. Propagation via eggs is called sexual reproduction. That is, in the life of freshwater hydra replaced both methods of reproduction.
Regeneration in the freshwater hydra
Hydra have an amazing ability toregeneration. If the individual is cut into two pieces, each very quickly grows back tentacles and sole. There are experiments conducted by the Dutch zoologist Tremblay, in which he was able to receive the new Hydra of the small pieces, and even to splice together the halves of different hydraulic. As shown by recent studies, such restoration of tissues and organs provide the stem cells of the animal.