QS Study

Eumetazoa is a major division of the animal kingdom comprising all multicellular forms except the sponges. It is a large group including most of the multicellular animals. Hence it is subdivided further into two groups.

  1. Diploblastic animals – having ectoderm and endoderm as two layers in the body wall. Ex: Coelenterata. Diploblastic organisms are organisms which evolve from such an ovum and include cnidaria and ctenophores.
  2. Triploblastic animals – having ectoderm, mesoderm, and endoderm as three layers in the body wall. Triploblasty is a condition of the blastula in which there are three primary germ layers: the ectoderm, mesoderm, and endoderm.

eumetazoa division

The Triploblastic animals are further divided into three groups based on the presence or absence of an embryonic body cavity called coelom.

  1. Acoelomata – no coelom Ex: Platyhelminthes
  2. Pseudocoelomata – with a false coelom Ex: Nematoda
  3. Coelomata – with a true coelom
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