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THE EARTHWORM - Biology

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					Biology of the Earthworm
     Biology of the Earthworm
1. Among the most common invertebrate animals are the
   annelids or earthworms.
2. The word, annelid, means “ringed” and refers to the
   segments found on all worms in this Phylum.
3. Each individual ring is called a somite and can be used to
   tell the age of the animal.
4. A mature worm has over 100 somites in its body.
5. They range in size from one-inch to the giant 11-foot worms of the
     tropics.
  Biology of the Earthworm
6. Earthworms live in soil which is chalky and
   moist.
7. They eat their way through the dirt and
   digest out any organic materials, excreting
   the rest as feces.
8. As they eat, a tunnel or burrow is formed
   from mucus which they produce in their skin.
    Digestive system

It is a straight tube and
runs from the first to the
last segments. It consists
of
mouth(peristomium),buc
cal cavity , pharynx,
oesophagus,a muscular
gizzard, stomach,
intestine and anus
      Biology of the Earthworm
9. The worm builds its
  burrow by forcing its
  head through cracks in
  the soil and eating it.
10. When they do this,
  they aerate and
  fertilize our gardens
  and help to further
  decomposition of
  decaying material.
  Biology of the Earthworm



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

				
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posted:10/26/2012
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