There are 300 known species of leeches contained in  4 orders. The hirudo medicinalis leech is part of the class  Hirudinea, order Gnathobdellida. It's an amphibious animal  is small or medium sized, requiring for their livelihood land  and water, living exclusively in freshwater. The medicinal  leech has a cylindrical body provided at each extremity with  a cup, slightly flattened dorsoventral and divided into a  number of 33-34 segments. Body shape varies with the  state in which the individual is, the contraction of muscles or  the digestive tract filled with blood. The exetile trunk has  strong muscles and in the bottom of the mouth it has three  maxillary wich have 3 proeminent jaws wich are sharp as a  needle, arranged in Y shape, a median and two lateral  anterior wich are moved by muscles. Through teeth there  are numerous openings of unicellular salivary glands wich  produce hirudin, which prevents the clotting of blood,an  anticoagulant substance ingested by the host. Blood is  stored in the stomach, separated by bottlenecks. Amount of  blood taken from an outlet is 5 times its body weight.  Medicinal leeches size varies between 7-14 cm and weight,  generally between 1 g - 3.5 g  and can survive without food  for 18-24 months. When not feeding it stays attached to  rocks or plants. Using suction cups, it can move. It expands  it's body, attaches with the cranial suction cup and then it  realeses it's caudal cup and it drags it's body forward.  Sensitive to noise and smells of chemicals. Temperature  influences their lives and the pace of development. At  temperatures below 15 degrees celsius they hibernate.                Brief description of the leech from the species                      Hirudo medicinalis Home About us Activity Description of leeches Use of leeches Terms of sale Contact Last update: September 8, 2010