Why are priapulidworms
(like the cactus worm) more complex than annelidworms?

priaupulidworms are more complex than annelidworms because the live in aquatic habitats and have distinct habits to survive in the habitat compare to annelidworms that reside in dry to moist habitats.

Explanation:

Priaupulidworms are small wormlike animals found mostly in sea. They have a swollen mouthpart called proboscis e.g cactus worm.

Annelidworms are segmented worm that reside in dry or moist habitat. They are biallateraly symmetrical and tripoblastic.