Hirudinea

noun plural

Hir·​u·​din·​ea ˌhir-(y)ə-ˈdin-ē-ə 

: a class of hermaphroditic aquatic, terrestrial, or parasitic annelid worms distinguished by a coelom nearly obliterated by connective tissue and reduced to a series of vascular sinuses, by modification of the hindmost segments into a sucking disk, and by the absence of parapodia and setae