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Facts about Earthworms For Kids

An earthworm is a tube-shaped, segmented worm found in the phylum Annelida. They are commonly found living in soil, feeding on live and dead organic matter.

  • An earthworm has a double transport system composed of coelomic fluid that moves within the fluid-filled coelom and a simple, closed blood circulatory system.
  • The central nervous system consists of two ganglia above the mouth, one on either side, connected to a nerve cord running back along its length to motor neurons and sensory cells in each segment.
  • Circumferential and longitudinal muscles on the periphery of each segment enable the worm to move.
  • Similar sets of muscles line the gut, and their actions move the digesting food toward the worm’s anus.
  • Larger terrestrial earthworms are also called megadriles, as opposed to the microdriles in the semiaquatic families Tubificidae, Lumbriculidae, and Enchytraeidae, among others.
  • The exterior of an individual segment is a thin cuticle over skin, commonly pigmented red to brown, which has specialized cellsthat secrete mucus over the cuticle to keep the body moist and ease movement through soil.
  • At the center of a worm is the digestive tract, which runs straight through from mouth to anus without coiling, and is flanked above and below by blood vessels (the dorsal blood vessel and the ventral blood vessel as well as a subneural blood vessel) and the ventral nerve cord, and is surrounded in each segment by a pair of pallial blood vessels that connect the dorsal to the subneural blood vessels.
  • There are also three giant axons, one medial giant axon (MGA) and two lateral giant axons (LGAs) on the mid-dorsal side of the ventral nerve cord.
  • Touching an earthworm stimulates the subepidermal nerve plexus which connects to the intermuscular plexus and causes the longitudinal muscles to contract, thereby the writhing movements when we pick up an earthworm.
  • It is differentiated into a buccal cavity (generally running through the first one or two segments of the earthworm), pharynx (running generally about four segments in length), esophagus, crop, gizzard (usually) and intestine.
  • Certain species of earthworm come to the surface and graze on the higher concentrations of organic matter present there, mixing it with the mineral soil.