There are 300 species of leeches known in 4 orders. Lipid Hirudo medicinalis is part of the Hirudinea Class, the order of Gnathobdellida. It is an amphibious animal of small or medium size, needing for its life and land and water, living exclusively in fresh water.
The medical lip has a cylindrical body provided at the ends with a suction cup, slightly twisted dorsoventrally and divided into a number of 33 – 34 segments. The shape of the body varies with the state of the individual, muscle contraction or digestive tract filled with blood.[:]