Earthworms reproduce sexually. Asexual
reproduction is absent. However some power of regeneration is present. Though
they are hermaphrodite, cross-fertilization takes place in them due to
protandrous condition ( A condition in
which male gametes mature earlier than
female gametes in hermaphrodite organisms) . It is preceded by copulation and
cocoon formation.
Copulation
It takes place during rainy seasons, generally
at night or early morning and lasts for about one hour. During it, two
earthworms come in contact of each other by their ventral surface facing
anterior end towards opposite direction in such a way that male genital pore of each earthworm lie
against a pair of spermethecal pores of other. The male genital apertures are
raised into papillae, which are inserted successively from behind to forward
into the spermethecal pores of other earthworm and discharge the spermatic and
prostatic fluid with sperms, which are stored in spermetheca.
After this exchange of sperms, the two
earthworms separate.
Cocoon formation and fertilization
Cocoon
formation begins after copulation. During it, clitellum produces a type of viscous
and gelatinous substance forming a broad membranous band around the