Details
Hirudo medicinalis
The medicinal leech is a freshwater blood-feeding leech long used in medicine. Its saliva contains compounds that keep blood flowing.
Map: Ecoregions 2017 © RESOLVE (CC BY 4.0) · Natural Earth (PD)
It inhabits Palearctic ponds, marshes, and slow freshwater. Vegetated shallow water used by amphibians and mammals provides feeding opportunities.
Length 5-20 cm; weight 1-10 g. The flattened elastic body has suckers at both ends, with greenish-brown or dark striping above. Small jaws line the mouth.
Nocturnal and solitary, it swims by undulating the body and attaches with suckers. It waits in shallow water for passing hosts.
A carnivore, it feeds mainly on vertebrate blood. Anticoagulant saliva lets it take a large meal and then go a long time without feeding.
Individuals are hermaphrodites but mate with another leech. After fertilization, cocoons are deposited in damp soil, and young feed from smaller hosts.
It is listed as Near Threatened. Wetland loss and collection pressure have affected some areas, while medical supplies now rely on controlled breeding.
