What is the perfection of worms in relation to coelenterates? Which class of worms is more perfect and why?

Worms, in contrast to coelenterates, have an organ level of organization, they are three-layered and bilaterally symmetric. The most highly organized type of worms are annelids. They have a secondary body cavity, nervous (periopharyngeal nerve ring and abdominal nerve cord), digestive (anterior, middle and hind intestine with anus), excretory (metanephridia), circulatory (closed), respiratory (through the skin or gills) and genital ( dioecious or hermaphrodite) systems.