Coelom is formed from the ‘primitive gut’ in

Any animal in which the mesoderm-lined body cavity (coelom) arises in the embryonic stage as an out pocketing of the developing gut (enteron) are said to have enterocoelom. This form of development, found in echinoderms (e.g., starfishes, sea urchins) and a few other invertebrate phyla and in chordates.