Contrary to popular belief, most leeches don’t rely solely on drinking blood. Some eat other, small invertebrates, and some feed off decomposing bodies.  Leeches that suck blood are called ‘Haemophagic’ leeches, ‘Haemo’ meaning blood, ‘Phago’ meaning to eat.  There are more than 600 species of leeches but only 15 of the species are used medicinally, so they are given a classification of their own – Hirudo Medicinalis or medicinal leeches.