Pseudocoelom or false coelom is characteristic of nematoda. It is a cavity, formed from outgrowth of blastocoel, is found between the body wall & the gut. This cavity is not lined by mesoderm. Echinodermata have true coelom lined with ciliated peritoneum coelom is greatly reduced in mollusca & is represented mainly by pericardial cavity, gonadal cavity & kidney. Annelida are coelomate having a perivisceral cavity divided into compartments