Reproductive system of Earthworm MCQ - Practice Questions with Answers

Reproduction and Development in Earthworm

• Earthworm is hermaphrodite, that is, male and female reproductive organs are present in the same individual. 
• Earthworms do not self- fertilise because testes mature earlier than the ovaries. 

Male reproductive system

• It consists of the following structures

1. Testes sacs- There are two pairs of testes sacs present in the 10th and 11th segments. Each sac encloses a testis and a spermiducal funnel.
2. Testes- Two pairs of testes are present inside testes sacs at 10th and 11th segments. These are the sites of gametogenesis.
3. Seminal vesicles- These are two pairs of structures present in 11th and 12th segments. The process of development to maturation of spermatozoa takes place inside them.
4. Spermiducal funnel- These are present in the 10th and 11th segments. These act as gateways of sperm reception and leads into vasa deferentia.
5. Vasa deferentia- The vasa deferentia run from 12th upto the 18th segment where they join the prostatic duct.
6. Prostate gland- lie one in each side of the gut from 16th to 21st segments. They produce a secretion which serves as a medium for the transfer of sperms. 
7. Accessory glands- Two pairs of accessory glands are present one pair each in the 17th and 19th segment. 

Female reproductive system

• It consists of the following structures

1. Ovaries- these are a pair of white minute masses attached to the septum present between 12th and 13th segments. These are the sites of gametogenesis.
2. Oviducts and oviducal funnel- these collect eggs and pass them to outside into the cocoon through a female genital aperture.
3. Spermathecae- Four pairs of spermatheca are located in 6th-9th segments (one pair in each segment). They receive and store spermatozoa during copulation

 Copulation and Cocoon formation

• The two worms come closer and lie in juxta position (opposite direction)
• The worms attach with each other with their ventral surfaces
• When copulation takes place the male genital papillae of one earthworm is inserted into the spermathecal aperture of the other earthworm
• This enables transfer of sperms and prostatic fluid 
• After copulation the two worms separate
• Now ova are released through female genital pore  (The earthworm that has received the sperms will secrete the ova too)
• The mature ova will stick to the undersurface of Clitellum due to glandular secretions 
• The worm now wriggles backwards and thus the clitellum reaches the region of spermathecae and the sperms also stick to clitellum
• The sperms and ova thus come in contact with each other
• The earthworm continues to move backwards and the clitellum is completely separated from the earthworm
• The sperms and ova thus undergo fertilisation and cocoon formation also takes place
• The fertilisation is outside the body but inside the cocoon
• After about three weeks, each cocoon produces 2-20 baby worms 
• Thus development is direct