Polychaetes are a class of annelid worms characterized by their segmented bodies and numerous bristle-like structures called chaetae. They are primarily marine organisms, found in various habitats from deep-sea environments to tidal pools. Polychaetes play a crucial role in the ecosystem, contributing to nutrient cycling and serving as a food source for many marine animals. These worms exhibit a wide range of forms and behaviors, with some being free-swimming while others are burrowers or tube-dwellers. Their diverse adaptations allow them to thrive in different environments, making them an important group for studying marine biodiversity and ecology.