ANIMAL KINGDOM Part-3, NCERT Class-11

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Body Organisation

Animals have three germinal layers of cell in their embryonic stage. Those layers are called Ectoderm, Endoderm and Meroderm. On the basis of presence of mesoderm or middle layer, animals are divided into two categories-

•Diploblastic:
Animals that have only two embryonic layers are called diploblastic body organisation. They lac the mesoderm layer. An undifferentiated layer called mesoglea is present instead of mesoderm
e.g. Coelenterates

•Triploblastic:
Animal that have all three embryonic layers are called to have triploblastic body organisation. Mesoderm is present in between Ectoderm and Endoderm.
e.g.Platyhelminthes to Chordates


  Body organisation (Germinal layers)
(a) Diploblastic
(b) Triploblastic

Click here for part 1 of this chapter
Click here for part 2 of this chapter

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