Why are coelomates superior to other body plants?

Coelomates such as annelids(eg earth worms) have true coeloms or eucoeloms. A true coelom ,unlike the psuedocoelom of nematodes, has tissues that can form muscle next to the digestive tract, allowing them to push food along more efficiently.

Coeloms provide a hydrostatic skeleton to aid movement, allows for more efficient circulation of nutrients and removal of wastes.

Hope this helps:))