Leech

Leeches
Scientific classification
Kingdom: Animalia Phylum: Annelida Class: Clitellata[?] Subclass[?]: Hirudinea
Orders
Arhynchobdellida[?] Rhynchobdellida[?]

A leech is a aquatic parasitic organism that sucks blood from animals to eat. It has a long history of use in medicine although today its use is mainly limited to limb reattachment procedures instead of the wide-ranging medical use of the past. Leeches were once so commonly used that doctors were popularly called leeches.