Polychaete worms are a diverse group of segmented worms belonging to the class Polychaeta. They are primarily found in marine environments, living in various habitats such as sandy or muddy sea floors. Polychaetes have a distinct body structure, featuring numerous bristle-like appendages called parapodia that help them move and breathe. These worms play a crucial role in the ecosystem by contributing to nutrient cycling and serving as a food source for many marine animals, including fish and crustaceans. Polychaetes exhibit a wide range of sizes and colors, with some species being brightly colored and others more subdued.