<P> The evolutionary origin of the coelom is uncertain . The oldest known animal to have had a body cavity was the Vernanimalcula . Current hypothesis include: (2) </P> <Ul> <Li> The acoelomate theory, which states that coelom evolved from an acoelomate ancestor . </Li> <Li> The enterocoel theory, which states that coelom evolved from gastric pouches of cnidarian ancestors . This is supported by research on flatworms and small worms recently discovered in marine fauna ("coelom") </Li> </Ul> <Li> The acoelomate theory, which states that coelom evolved from an acoelomate ancestor . </Li> <Li> The enterocoel theory, which states that coelom evolved from gastric pouches of cnidarian ancestors . This is supported by research on flatworms and small worms recently discovered in marine fauna ("coelom") </Li>

Advantage and disadvantage of a coelom in annelids