Comment upon the gametic exchange in earthworm during mating.
The mating process in earthworms is referred to as copulation which occurs during the rainy season. The gamete exchange in the earthworms occur through the following sequential steps:
i) Two earthworms come closer to each other and they get ventrally attached to each other in the opposite direction.
ii) The copulation process begins and the male genital pore (i.e., papilla) of one earthworm is inserted into the spermathecal pore of the other earthworm.
iii) The earthworm remains mutually close together by the penetration of setae in their bodies.
iv) Sperm and prostatic fluid of the earthworm are exchanged and the spermathecal pore stores the spermathecae.
v) The earthworms remain attached for an hour and the sperm and egg are passed into cocoon which gets secreted by the clitellar gland present in the 14th to the 16th segment of the earthworm.
Therefore, gamete exchange of earthworms occur through cross-fertilization and external fertilization.