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Question
Comment upon the gametic exchange in earthworms during mating.
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Solution
Time
The mating process happens during the rainy season.
Bisexual
Although earthworms are bisexual, meaning both testes and ovaries are present in the same organism, they cannot fertilise themselves as the male and female genital pores are at different locations and the earthworms are protandrous.
Male reproductive system
The male reproductive system includes:-
- Testis- There are two pairs in the 10th and 11th segments.
- Vasa deferentia- Two pairs of vasa deferentia run up to the 18th segment where they join the prostatic duct.
- Genital pore- The common prostate and spermatic duct open outside through the male genital pore present on the ventro lateral side of the 18th segment. The sperms come out from the body through this pore.
Female reproductive system
The female reproductive system includes the following:-
- Ovaries- One pair attached to the intersegmental septum of the 12th and 13th segment and produces ova.
- Ovarian funnels- Present beneath the ovaries.
- Oviducts- Arise from the ovarian funnel. There are two in number that join together and open to the outside of the body through the female genital pore.
- Genital pore- Present on the ventral side of the 14th segment through which the eggs come out of the body.
- Spermatheca-Stores the spermatozoa and there are four pairs (6th to 9th segment). They open to the outside by pores called spermathecal pores. These pores receive sperms during copulation from another worm.
Copulation
The mating pair overlap front ends ventrally in such a way that the male genital pore (in the 18th segment) of one worm lies opposite to the spermathecal pore (present from 6th to 9th segment) of the other. Further the mutual exchange of gametes takes place.
Clitellum produces mucus to form cocoons in which the gametes and nutritive fluid are deposited. The ova are fertilized by the sperm cells within the cocoon. This then slips off the worm and is deposited in the soil.
Development
Development is direct and the worms form inside the egg case or cocoon.
The mating process happens during the rainy season.
Bisexual
Although earthworms are bisexual, meaning both testes and ovaries are present in the same organism, they cannot fertilise themselves as the male and female genital pores are at different locations and the earthworms are protandrous.
Male reproductive system
The male reproductive system includes:-
- Testis- There are two pairs in the 10th and 11th segments.
- Vasa deferentia- Two pairs of vasa deferentia run up to the 18th segment where they join the prostatic duct.
- Genital pore- The common prostate and spermatic duct open outside through the male genital pore present on the ventro lateral side of the 18th segment. The sperms come out from the body through this pore.
Female reproductive system
The female reproductive system includes the following:-
- Ovaries- One pair attached to the intersegmental septum of the 12th and 13th segment and produces ova.
- Ovarian funnels- Present beneath the ovaries.
- Oviducts- Arise from the ovarian funnel. There are two in number that join together and open to the outside of the body through the female genital pore.
- Genital pore- Present on the ventral side of the 14th segment through which the eggs come out of the body.
- Spermatheca-Stores the spermatozoa and there are four pairs (6th to 9th segment). They open to the outside by pores called spermathecal pores. These pores receive sperms during copulation from another worm.
Copulation
The mating pair overlap front ends ventrally in such a way that the male genital pore (in the 18th segment) of one worm lies opposite to the spermathecal pore (present from 6th to 9th segment) of the other. Further the mutual exchange of gametes takes place.
Clitellum produces mucus to form cocoons in which the gametes and nutritive fluid are deposited. The ova are fertilized by the sperm cells within the cocoon. This then slips off the worm and is deposited in the soil.
Development
Development is direct and the worms form inside the egg case or cocoon.
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