One of the most common types of leeches. It inhabits the northern half of Eurasia, north of Africa, also inhabits the Americas, where there are at least 20 species of the same genus. Its distinctive feature is a lenticular platelet of yellow or brown color, located on the back between the 12th and 13th rings. It is very mobile, which makes it easier for her to attack the larvae of water insects, crustaceans, small worms, other leeches and small invertebrates, which she often sucks in full. At the same time, due to its mobility, it is much more often than cochlear leeches that gets into the stomachs of fish. Lives Helobdella stagnalis only a year. Hatched hawks from the cocoons in the spring grow rapidly and can reproduce in July-August; Then, next spring, they once again lay eggs and die.