Earthworm Reproduction

Earthworms are hermaphrodites. Testis and ovary are present in the same individual.

Male reproductive organ

  • Two pairs of testis are present in the 10th and 11th segments.
  • The vas defferentia from the testis joins the prostatic duct in the 18th segment.
  • Paired Accessory glands at present in the 17th and 19th segments.
  • The prostate gland and the spermatic duct ‘vasa deferentia’ open into the exterior through a pair of male genital pores.
  • Four pairs of spermathecae are found in the 6th – 9th segments.
  • They receive and store spermatozoa during copulation.

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Female reproductive organ

  • A pair of ovaries is found near the septum between 12th and 13th segments.
  • Just below the ovary, ovarian funnels present.
  • They collect the eggs and transfer them to the oviduct which opens out to the female genital pore present on the ventral side of the 14th segment.

Fertilization

  • Even though earthworms are hermaphrodites, cross fertilization is the most common means of sexual reproduction.
  • Exchange of sperms occurs between two earthworms during mating.
  • Packets of sperms called ‘spermatophores’ are transferred from one worm to another and vice versa.

  • After this transfer, mature sperms, egg cells and some nutritive fluids are deposited in the cocoons formed by the glands cells of clitellum.
  • Fertilization of egg takes place within this cocoon.

Development

  • After 3 weeks the baby worms (2-20 in number) are released from the cocoon.
  • The development is direct without any larval stage.
  • Earthworms also have limited powers for re-generation.

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