Polychaetes are a class of annelid worms, characterized by their segmented bodies and numerous bristle-like structures called setae. They are primarily marine organisms, found in various habitats from deep ocean floors to tidal pools. Polychaetes play essential roles in the ecosystem, contributing to nutrient cycling and serving as food for many marine animals. These worms exhibit a wide range of sizes and colors, with some species reaching lengths of over a meter. Polychaetes can be free-living or burrowing, and many have specialized adaptations for their environments. Their diverse forms include tube-dwelling species that create protective structures and predatory forms that actively hunt for prey.