rag worm, also called clam worm (genus Nereis), any of a group of mostly marine or shore worms of the class Polychaeta (phylum Annelida). A few species live in fresh water.

What makes Polychaeta different than annelids?

Polychaetes differ from other annelids in having a well differentiated head with specialized sense organs and no clitellum. They have many setae, usually arranged in bundles on the parapodia. ... The sense organs in polychaetes are more highly developed than in oligochaetes.

What kind of animal is a polychaete?

polychaete, any worm of the class Polychaeta (phylum Annelida). About 8,000 living species are known. Polychaetes, which include rag worms, lugworms, bloodworms, sea mice, and others, are marine worms notable for well-defined segmentation of the body.