The body form of leeches, which becomes a modeling object, is a valid ectosomatic feature. It describes borders, in which, we can find internal organs of an individual. The range of realization of the body form, proposed for different groups of leeches, characterize their life spaces. These life spaces are distinct in term of position of body of leeches to the host and to the environment. Individuals originated from the Caspian Sea, Baikal Lake, and from fresh waters of Italy, Finland, Russia, Germany and Poland. Over 1200 individuals, belonging to 11 genera were measured. The measurements have been made according to the model of the leech body form.