4. Kingdom Animalia - part 05 - Phylum : Platyhelminthes

 

4. Kingdom Animalia - part 05 - Phylum : Platyhelminthes


Phylum : Platyhelminthes (platy -flat, helminth -worms) :

  • e.g. Planaria, Taenia (Tapeworm), Fasciola (Liver fluke). 
  • Body of these animals is dorsoventrally flattened, hence are called as flat worms. 
  • Animals are acoelomate, triploblastic showing organ-system grade of organization.
  • Mostly endoparasitic and few are free-living.
  • Parasitic forms shows presence of hooks and suckers for attachment to the body of host.
  • Body is covered by cuticle (in parasites) or cilia (in free-living forms)
  • Digestive system is generally absent in parasitic forms, but in freeliving forms, it is incomplete (blind-sac plan).
  • Animals have flame cells or protonephridia, helpful for excretion and osmoregulation.
  • Animals are hermaphrodite (bisexual).
  •  Self fertilization is seen. 
  • Few have high power of regeneration and show polyembryony.

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