Living reference work entry
Hirudinea, from Latin: Hirudo = leech
Hirudinea is a subclass of Annelida.
In general, members of the Hirudinea, which are endowed with a complete intestinal tract, look like platyhelminths and are dorsoventrally flattened monoecious animals ( Hermaphrodites). Mostly they develop 32 inner segments (except for 29 in Acanthobdella), which each corresponds to 2–14 outer annuli (some authors count 34 segments). Except for Acanthobdella, the Hirudinea, parasitic or not, are characterized by an oral sucker and a posterior disklike acetabulum, which act as strong holdfast organs supporting movements on the surface of animal hosts, plants, etc. (Figs. 1, 2, 3, 4, and 5, Hirudo medicinalis/Figs. 1 and 2). Bloodsucking leeches produce enzymes (e.g., hirudin) preventing coagulation of blood during feeding. Typically, closed circulatory vessels and a definitive respiratory system are lacking in most species, and the coelom cavities are restricted to a...
KeywordsOral Sucker Excretory System Medicinal Leech Anterior Intestine Outer Annuli
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