Biology of the Earthworm

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Biology of the Earthworm
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Biology of the Earthworm

• Among the most common invertebrate animals are
  the annelids or earthworms. The word, annelid,
  means ringed and refers to the segments found
  on all worms in this Phylum. Each individual
  ring is called a somite and can be used to tell
  the age of the animal. A mature worm has over
  100 somites in its body.

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Biology of the Earthworm

• There are over 170 different types of segmented
  worms and over 3,000 types of worms in general.
  They range in size from one-inch to the giant
  11-foot worms of the tropics. Some are reddish
  brown others can be bright colored such as blue
  and purple ones which live in the Philippines.
  The most common segmented worm, however, is the
  Lumbricus terrestris. Earthworms can be found
  the world over, except in areas which are arid or
  arctic.

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Biology of the Earthworm

• Earthworms live in soil which is chalky and
  moist. They eat their way through the dirt and
  digest out any organic materials, excreting the
  rest as feces. As they eat, a tunnel or burrow
  is formed from mucus which they produce in their
  skin.

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Biology of the Earthworm

• When they do this, they aerate and fertilize our
  gardens and help to further decomposition of
  decaying material. The worm builds its burrow by
  forcing its head through cracks in the soil and
  eating it.

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Biology of the Earthworm

• It produces mucus which is used to plaster the
  walls of the burrow to prevent cave-ins. During
  winter or very dry seasons, the worms migrate to
  deeper levels, down to about 10 feet.

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Biology of the Earthworm

• After moving to deeper levels, the worms undergo
  a period of quiescence (quiesce comes from the
  word quiet). During this time, they squeeze out
  about 70 of their body water in order not to
  freeze or dehydrate. They roll up into a ball
  for a period of up to two months. When spring
  rains or snow melt comes, they absorb water or
  re-hydrate themselves and return to life on the
  surface. The average life span of an earthworm
  is about 4-5 years.