Q.3:- How useful is the study of the nature of body cavity and coelom in the classification of animals?
The presence or absence of the body cavity gives a clue about a particular animal’s position in evolutionary ladder. The absence of coelom indicates that the animal is yet to develop a functional dividion of labour to carry out various activities. This indicates towards a simplicity of activities going on inside the body. The presence of coelom paves the way for evolution of a more complex and more efficient organ system for various activities.