Explain the Reproductive System of Earthworm
Earthworms are hermaphrodites, i.e., both testis and ovaries are present in the same individual. The 10th and 11th segments consist of two pairs of testes,
with their vast differential running up to the 18th segment, thus joining the prostatic duct.
One pair of accessory glands is present in each 17th and 19th segment. Four pairs of spermathecae are present in the 6th-9th segment with one pair in each segment, thus storing sperms for copulation. The prostate and the spermatic duct open in a pair of male genital pores present in the ventrolateral side of the 18th segment.
In the 12th and 13th segments, one pair of ovaries is attached to the inter-segmental septum. Just below the ovaries, the ovarian funnels continue to run as an oviduct and join together to open into the exterior on the ventral side as a female genital pore present in the 14th segment.
During copulation, a mutual exchange of sperm occurs through sperm packets called spermatophores. The mature egg and sperm cells along with nutritive fluid are deposited in cocoons secreted by the glandular cells of clitellum. The cocoons containing the eggs fertilized by the sperms are slipped off through the body of the earthworm.
These cocoons are then deposited in the soil to promote the fertilization and development of embryos. After about three weeks, the cocoons produce two to twenty offspring. The development of baby worms is direct without any larval stage.