The process of giving birth to the young ones of their own kind for continuation of generation is called reproduction. The organs which are concerned with reproduction are called reproductive organs. These organs form reproductive system.

Earthworm are bisexual or hermaphrodite or monoecious animal i.e both male and female reproductive organs are found in the same individual. But self fertilization is impossible as testis and ovaries mature at different times. The relative position of male and female genital openings also makes the self fertilization impossible. Therefore cross fertilization takes place by copulation.

Male Reproductive System

Male reproductive system of earthworm consists of following reproductive organs:

1. Testes sacs


2. Testes


3. Seminal vesicles


4. Vasa deferentia


5. Prostate glands


6. 
   Accessory glands                                                                                                                                             

Testes sacs: There are 2 pairs of testis sacs on the 10 and 11 segments. Testes sacs are white or yellow in color.  The cavities of 2 testes sacs of the same segment communicate with each other.

Testes: Testes are male gonads. There are 2 pairs of testes in the 10 and 11 segments inside the testes sacs. Testes are attached to the anterior wall of the testes sacs. Each testes contains 5-8 finger like projections. The process of formation of sperms from the testes is called spermatogenesis. In case of earthworm testes produce immature sperms.

Seminal vesicles: There are 2 pairs of seminal vesicles present in the 11 and 12 segment. Seminal vesicles are somewhat round or oval in shape. Two testes sacs of the 10 segment communicate with seminal vesicles of the 11 segment. Similarly 2 testes sac of 11 segment communicate with seminal vesicles of 12 segment . Immature sperms enter the seminal vesicles through seminal funnel for maturation. After maturation, mature sperms return to their own testes sacs.

Vasa deferentia: Vasa defenterentia are the ducts for passing sperms so vasa deferentia are also called spermatic ducts. There are 2 pairs of vasa deferentia, 1st pair starts from 10 segment and second pair start from 11 segment. The front portion of these ducts bear funnel like structure with cilia are called spermatic funnel. These ducts run posteriorly up to the 18 segment then enters the prostate glands from 11 segment.

Prostate glands: There is a pair of large, flat, white and irregular structure called prostate gland. Prostate glands start from 16-17 segment up to 20 or 21 segment. From the prostate glands large ducts arise which are called common spermatic and prostate ducts. These ducts opens in the 18 segment as male genital pores. Through these pores male gametes are discharged.

Accessory glands: There are 2 pairs of accessory glands present in the 17 and 19 segment. The secretion of these accessory glands help in the attachment of the 2 earthworm during copulation.

Female Reproductive System

Female reproductive system of earthworm includes following reproductive organ

1. Ovaries


2. Oviducts


3. 
   Spermatheca                                                                                                                             

1. 
   Ovaries: Ovaries are female gonads. There is a pair of ovaries in the 13 segment. They are situated below the alimentary canal one on either side of the nerve cord. The structure of ovary consists of no of filaments fused proximally while free distally. Proximal end of the filaments form a compact basal part. Each filament is a beaded in appearance which consists of many ova in the different stages of development. The process of producing ova form the ovary is called oogenesis. Mature ova detatch from the ovary.                                                                                                                                                                                                                                                                                     
   


2. Oviducts: Ducts for passing ova are called oviducts. There is a pair of oviduct which are funnel in shape. Oviducts start from middle of 13 segment. The front portion of oviducts are expanded with cilia oviducal funnel. Oviducts of the both sides fuse in the middle of the 14 segment and form a commo opening is called female genital pore. Through this pore ova are passed out.                                                                                                                                                                                                                                                   


3. Spermathecae: There are 4 pairs of spermathecae present in the 6,7,8 and 9 segments. Spermathecae are also called seminal receptacles. Spermathecae are flask shaped which consists of swollen ampulla and a short branch diverticulum. Spermathecae receive sperms from another earthworm during copulation and store for fertilization. So spermathecae are also called store house of sperms.