1.

List the important features of the phylum Platyhelminthes?ORWrite the general characters of the phylum Platyhelminthes. Mention three classes and give one example for each.

Answer»

Phylum Platyhelminthes includes the flatworms which shows the following characters.

  • Multicellular organisms with organ grade of organisation. 
  • The body is bilaterally symmetrical and dorsoventrally flattened. 
  • The body wall is triploblastic with ectoderm, mesoderm and endoderm forming the layers. Coelom is totally absent.
  • The body is unsegmented and varies in shape. It may be elongated, flattened, ribbon like or leaf-like. 
  • The parasitic forms are protected by a thick cuticle and bears, hooks, spines or suckers for attachment.
  • Digestive, circulatory, respiratory and skeletal systems are absent. 
  •  Excretion occurs by excretory cells called flame cells which form the protonephridia.
  • Nervous system consists of nerve aggregations called ganglia.
  • Sexes are mostly united (Hermaphrodites). Reproduction is by asexual and sexual methods. Development is indirect.

Class – Turbellaria Eg. lanaria

Class – Trematoda Eg. Fasciola hepatica

Class – Cestoda Eg. Taenia solium



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