Excretory or Nephridial System of Earthworm
The excretory organs are segmentally arranged, microscopic, coiled tubules called nephridia. Nephridia are ectodermal in origin. These are typically unbranched, and their inner ends open into coelom by a ciliated funnel, called nephrostome. A large number of small-sized nephridia are found in each segment which are called micronephridia and mesonephridia. Nephridia occur …