CBSE Class 9 Answered

The body of some animals is made up of three layers of cells, the outer ectoderm, the middle mesoderm and the inner endoderm. The coelomic cavity or the coelom is the space enclosed by the mesoderm where the internal organs are suspended. Coelom is defined as a body cavity lined by an epithelium derived from the mesoderm. Organs formed inside the coelom can freely move, grow and develop independently of the body wall while the coelomic fluid cushions and protects them from mechanical shocks. The animals that have a true coelom are known as coelomic or eucoelomic. Example: Phylum Annelida, Phylum Chordata etc.