Question

What are the differences between pseudocoelom and true coelom?

Answer 1

There are three germ layers which give rise to all the tissues/organs of a fully formed individual;Ectoderm (Outer layer), Mesoderm (middle layer) and Endoderm (inner layer).
From the endoderm arise the lining of the guts.The mesoderm gives rise to the lining of the coelomic cavity.
Coelom or body cavity is the cavity between body wall and gut wall. On the basis of presence or absence of this coelom animals are classified into :
Eucoelomate(True coelom):
1. Coelomate animals have a coelom, this is a body cavity that has a mesodermal lining.
2. e.g. Mollusca, Annelida, Tardigrada, Arthropoda, Echinodermata, Hemichordata, Chordata.
Pseudocoelomate:
1. They have a body cavity but it is not lined with mesodermal cells.
2. Mesoderm is present as scattered pouches in between ectoderm and endoderm.
3. e.g. Gastrotricha, Rotifera, Nematoda, Nematomorpha, Acanthocephala.
Acoelomate:
1. They have no true body cavity.
2. e.g. Porifera ,Cnidaria , Ctenophora , Platyhelminthes, Mesozoa, Nemertina.