Phylum Aschelminthes- Nematoda


 
 
Concept Explanation
 

Phylum Aschelminthes- Nematoda

Phylum Aschelminthes (Nematoda): Generally called roundworms, these organisms have narrow bodies which are round in cross section. Their characteristics are :

  • They are bilaterally symmetrical, unsegmented and triploblastic.
  • The internal organs lie in a pseudocoelom (not a true coelom).
  • The alimentary canal (gut) is tubular and complete with a mouth and an anus. They lack a circulatory system.
  • Roundworms reproduce sexually and the sexes are separate.
  • Most of them are free-living, many live in moist soil. Some live in freshwater, while others are marine.
  • Of the parasitic species, some live in the body of plants, while others make animals their hosts.
  • The genus Ascaris has several parasitic species, of which Ascaris lumbricoides is the common roundworm which lives in the intestine of man. Another parasitic genus is Wuchereria. The worm that causes filariasis or Elephentiasis belongs to this genus. Pinworms (Enterobius), hookworms, guineaworms, trichinia worms are all disease- causing organisms belonging to this phylum.
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    Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    Which of the following is a common characteristic of flatworms and roundworms?

    Right Option : C
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    Explanation
    Question : 2

    Symmetry present in aschelminthes is __________________

    Right Option : A
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    Explanation
    Question : 3

    Elephantiasis is caused by __________

    Right Option : A
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    Explanation
     
     
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