Invertebrates introduction; classification of organism; evolutionary relationship and tree diagram; pattern of organization

The lower invertebrates include various phyla such as Protozoa, Porifera, Coelenterata(Cnidaria), Platyhelminthes and Nematoda. On the other hand, the higher invertebrates are generally larger in size and possess a complex body organisation. These occupy higher position in the phylogenetic tree of the Animal Kingdom.

Reference:

  • Zoology 4th Edition by Miller, S.A. and Harley, J.B.