What structures are lacking in the annelid's mouth that more advanced animals have?

Structures in the mouth region of the Annelids vary in a wider range. There are some annelids evolve jaws, which can be used in seizing their victims and preys, biting pieces of vegetation, or grasping decomposing matter. Even though some have evolved their jaws, majority of them are filter feeders. What lacks them that most advanced animals have? they dont have teeth.