Tag: introduction to reproduction

The number of ovaries present in Earthworm is one pair of ovaries. One pair of ovaries is attached at the intersegmental septum of the 12th and 13th segments. Ovarian funnels are present beneath the ovaries which continue into the oviduct and open on the ventral side.

Earthworms are monoecious or hermaphrodite (have both male and female sex organs) but are protandrous. The testes mature earlier than ovaries and hence, self-fertilisation is avoided.
Thus, the correct answer is option A.

Earthworm is hermaphrodite. There are two pairs of testes present in the 10th and 11th segments. Their vasa deferentia run up to the 18th segment where they join the prostratic duct. The prostate and spermatic duct open to the exterior by a pair of male genital pores on the ventrolateral side of the 18th segment. 

Four pairs of spermathecae are located in 6th-9th segments. They receive and store spermatozoa during copulation. One pair of ovaries is attached at the inter-segmental septum of the 12th and 13th segments. Ovarian funnels are present beneath the ovaries which continue into the oviduct, join together and open on the ventral side as a single median female genital pore on the 14th segment.

In Earthworm there are four pairs of spermathecae which are located in the 6th - 9th segments one pair in each segment. They receive and store spermatazoa during copulation. One pair of ovaries is attached at the inter-segmental septum of the 12th and 13th segments.

A pair of male genital pores is present on the ventrolateral sides of the 18th segment. Numerous minute pores called nephridiopores open on the surface of the body. In each body segment, except the first, last and clitellum, there are rows of S-shaped setae, embedded in the epidermal pits in the middle of each segment.

Asterias, Musca domestica and butterfly include a larval stage in their life cycle. Whereas in the case of Pheretima, there is no larval stage involved and the development is direct mode of development.

Answer is option A i.e. "One hour"
Copulation lasts for about an hour. Then the worms separate and later (after some day) they lay their eggs in cocoon. Cocoon formation takes place after copulation, when ovaries mature.

Spermathecae, which are four pairs are arranged one each in 6,7,8 and 9 th segments. Spermathecae are also called as seminal receptacles as they store spermatozoa from another worm  in the diverticular region during copultion. The ampulla of spermathecae nourish the sperms.