How useful is the study of the nature of body cavity and coelom in the classification of animals?

Explanation

The nature of body cavity and coelom is very important. It divide the animals into three categories like coelomate, acoelomate and pseudocoelomate. The coelom is a space between body wall and gut wall but lined by mesoderm. The animal having a cavity is called coelomate. Example: Chordates, annelids etc. Those who lack coelom are called acoelomates. Example: Platyhelminthes. The animals whose coelom is not lined by mesoderm are known as pseudocoelomate. Example : Nematodes.