Earthworm

  Acanthodrilidae
  Ailoscolecidae
  Alluroididae
  Almidae
  Criodrilidae
  Eudrilidae
  Exxidae
  Glossoscolecidae
  Lumbricidae
  Lutodrilidae
  Megascolecidae
  Microchaetidae
  Ocnerodrilidae
  Octochaetidae
  Sparganophilidae

Earthworm is the common name for the largest members of the Oligochaeta (which is either a class or subclass depending on the author) in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening to the outside of the body posterior to the female pores, even though the male segments are anterior to the female. Cladistic studies have supported placing them instead in the suborder Lumbricina of the order Haplotaxida. Folk names for earthworm include "dew-worm", "rainworm", "night crawler" and "angleworm".

Earthworms are also called megadriles (or big worms), as opposed to the microdriles, which include the families Tubificidae, Lumbriculidae, and Enchytraeidae, among others. The megadriles are characterized by having a multilayered clitellum (which is much more obvious than the single-layered one of the microdriles), a vascular system with true capillaries, and male pores behind the female pores.