A form of segmented worm
- Leeches belong to the phylum Annelida and comprise the subclass Hirudinea.
- Like Earthworms, they share a clitellum and are hermaphrodites (reproductive organs associated with both male and female sexes).
- Majority of leeches live in freshwater environments.
- They have been historically used in medicine to remove blood from patients.
- Hirudo medicinalis is the medicinal use of leeches.
- Most leech species do not feed on human blood, but instead prey on small invertebrates, which they eat whole.
- Their sizes range from 1 to 25 centimeters.
- They do not eat many times but eat a lot in one go.
- They keep feeding up to five times their body weight after which they fall down (because of their weight).
- There are 650 known species of leeches.
- They have 32 brains, three mouths and millions of teeth.
- The bite of a leech is painless because of its own anaesthetic.
- The first leech was used in medicine about 1000 B.C., probably in ancient India.
- The Nervous System of the leech is very similar to the human.
- The main species of leech, the Hirudo, is an endangered species.