Grube, 1850
The subclass that represents four families of leeches, they are not treated in this guide.
Description
Leeches are easily recognized by their muscular, contractile bodies and the suckers, one at each extremity, with which they adhere to any firm surface.
The fine external annulation does not correspond to the internal segmentation. Chaetae are lacking. Clitellum developing in mature individuals.
Distribution
Cosmopolitan.
Ecology
In freshwater habitats very common, some taxa in marine habitats, in warmer region common also in terrestrial habitats. Both free-living and parasitic.
Reproduction
Only sexual. Cocoons either free or brooded under the mother's body.