River perlovitsy and bezzubki reach 23 and even more than centimetres at length. They differ from others unless that the muscular lock at perlovitsy strong, at bezzubok it is absent, and shutters are kept by the switching muscles which are settling down on forward stupid and back sharper the ends. Life expectancy bezzubok varies within 10 years, at perlovits - 12 years, fruitfulness of the first - from 200 to 700 thousand eggs, the second - have less. The sexual maturity comes at those and others on the second - the third year of a life. Spawning occurs basically in the summer, often in stages. Bezzubka eats small live beings, perlovitsa - seaweed and particles organic detrita. Both that, and another as we marked, eat not only fishes, feed them to poultry, pigs and other pets.
Except these, large molluscs, is and considerably smaller kinds. It - sharovki , length of their body - to 25 mm, and goroshinki with length of a body to four millimetres. Walls at these molluscs very thin, however, these animals have a teeth. In the left shutter is available two separate teeth, and in right - one obtusangular tooth. They live as in flowing, and stagnant water, on sand and an oozy ground.
Lives sharovka no more than year, breeds twice a year, in June-July and in August-September at achievement of length of a body of 8-9 mm. Eats detritom, diatomovymi and protokokkovymi seaweed, bacteria, infusorians, a small zooplankton, various fossils. Is an active filtration organism of water. SHarovka serves as a favourite forage of almost all fresh-water fishes.