Biology EARTHWORM: REPRODUCTIVE SYSTEM

KEY TOPICS

`star` Reproductive System
`star` Mode of Reproduction
`star` Assistance in Farming



REPRODUCTIVE SYSTEM

● Earthworm is `color{Brown}"hermaphrodite"` (bisexual), i.e., `color{violet}"testes and ovaries"` are present in the same individual.

● There are `color{violet}"two pairs of testes"` present in the 10th and 11th segments.

● Their `color{violet}"vasa deferentia"` run up to the 18th segment where they join the `color{violet}"prostatic duct"`.

● Two pairs of `color{violet}"accessory glands"` are present one pair each in the 17th and 19th segments.

● The common `color{Brown}"prostrate and spermatic duct"` (vary differential) opens to the exterior by a pair of `color{violet}"male genital pores"` on the ventro-lateral side of the 18th segment.

● `color{Brown}"Four pairs of spermathecae"` are located in 6th-9th segments (one pair in each segment).

● They receive and store `color{violet}"spermatozoa during copulation"`.

● One pair of ovaries is attached at the `color{violet}"inter-segmental septum"` of the 12th and 13th segments.

● `color{Brown}"Ovarian funnels"` are present beneath the ovaries which continue into `color{violet}"oviduct"`, join together and open on the ventral side as a single median `color{violet}"female genital pore"` on the 14th segment



MODE OF REPRODUCTION

● A `color{violet}"mutual exchange of sperm"` occurs between two worms during `color{violet}"mating"`.

● One worm has to find another worm and they `color{violet}"mate"` juxtaposing `color{violet}"opposite gonadal openings"` exchanging packets of sperms called `color{Brown}"spermatophores"`.

● Mature `color{violet}"sperm and egg"` cells and `color{violet}"nutritive fluid"` are deposited in cocoons produced by the `color{Brown}"gland cells of clitellum"`.

● `color{violet}"Fertilisation and development"` occur within the `color{Brown}"cocoons"` which are deposited in soil.

● The `color{violet}"ova (eggs)"` are fertilised by the `color{violet}"sperm cells"` within the cocoon which then `color{violet}"slips off the worm"` and is `color{violet}"deposited"` in or on the soil.

● The cocoon holds the `color{violet}"worm embryos"`.

● After about 3 weeks, each cocoon produces `color{violet}"two to twenty baby worms"` with an average of four.

● Earthworms `color{violet}"development is direct"`, i.e., there is `color{Brown}"no larva"` formed.



ASSISTANCE IN FARMING

● Earthworms are known as `color{Brown}"friends of farmers"`because they make `color{violet}"burrows in the soil"` and make it `color{violet}"porous"` which helps in respiration and penetration of the developing plant roots.

● The process of `color{violet}"increasing fertility of soil"` by the earthworms is called `color{Brown}"vermicomposting"`.

● They are also used as `color{violet}"bait in game fishing"`.

 
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