Where do polychaete worms live?

Most polychaete worms live in the ocean, where they occupy a variety of marine environments. Depending on the species, they may float in the water, burrow into the sea floor, wander along the bottom, or reside within tubes they construct themselves.12

While they are primarily marine, their habitats are diverse. Some species engage in commensalism, living within the tubes of other sedentary polychaetes, in the mantle cavities of mollusks, or on the surfaces of echinoderms like starfish and sea cucumbers. A few species, such as the feather duster (Manayunkia speciosa), are found in freshwater environments, including rivers and the Great Lakes of the United States. Additionally, some atypical groups, such as the Myzostomida, live as commensals or parasites on or within other organisms.31