explain the reproductive system of earthworm.

Mating occurs on the surface, most often at night. Earthworms are hermaphrodites; that is they have both male and female sexual organs. The sexual organs are located in segments 9 to 15. Earthworms have one or two pairs of testes contained within sacs. There are two or four pairs of seminal vesicles which produce, store and release the sperm via the male pores. Ovaries and oviducts in segment 13 release eggs via female pores on segment 14, while sperm is expelled from segment 15. One or more pairs of spermathecae are present in segments 9 and 10 (depending on the species) which are internal sacs that receive and store sperm from the other worm during copulation. As a result, segment 15 of one worm exudes sperm into segment 9 and 10 with its storage vesicles of its mate. Some species use external spermatophores for sperm transfer.