Eudrilids further differ from megascolecids, and ocnerodrilids in the development of internal fertilisation with the equivalent of the spermathecae opening directly to the ovisacs, allowing sperm to combine with the eggs from the ovaries via a female opening in segment 14.
Eudrilids, megascolecids, and ocnerodrilids exhibit distinct reproductive strategies, characterized by the direct connection of the spermathecae to the ovisacs, enabling sperm to fertilize eggs within the ovaries through a designated opening in segment 14.