Reproductive - The earthworms are hermaphroditic, with a complete set of organs for both sexes. The male organs of an earthworm are the testes, the seminal vesicles, and the sperm ducts; the female organs are the ovaries, the oviducts, and the seminal receptacles. Copulation occurs when two worms lie ventral surface to ventral surface with the heads pointing in opposite directions. The clitellum, a smooth girdle about each worm secretes mucus, after which the sperm leave the sperm ducts and travel to the seminal receptacles of the partner. The clitellum later produces a slime tube, which is move along over the head of the worm by muscular contractions. Into this tube are deposited eggs from the oviducts and sperm from the seminal receptacles. The slime tube forms a cocoon within which the miniature worms develop. There is no larval stage.
Respiratory - A earthworm has no respiratory organ. It takes in oxygen directly through its skin and gives off carbon dioxide. Its skin is always moist for allowing efficient absorption of oxygen dissolved efficient in the water.