any of a group of mostly marine or shore worms of the class Polychaeta (phylum Annelida). A few species live in fresh water. Other common names include mussel worm, pileworm, and sandworm. Rag worms vary in length from 2.5 to 90 cm (1 inch to 3 feet); they are commonly brown, bright red, or bright green. Rag worms are perhaps the most highly developed of the annelids. The head bears sharp retractable jaws. The first segment of the body has two short tentacles and four eyes; the second segment has four tentacle-like cirri. The number of body segments may exceed 200. All but the first two segments have a pair of parapodia-flat outgrowths bearing bristles-used for locomotion. Breathing is through gills. Rag worms' principal foods are other worms and tiny sea animals
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