Polynoididae

Polynoidae is a large and diverse family of marine polychaete worms, commonly known as scale worms. They are characterized by the presence of elytra, which are modified dorsal structures resembling scales, arranged in two rows along their bodies. These elytra can vary greatly in shape, size, and color among different species, serving functions such as protection and possibly aiding in locomotion.

These worms are found in all the world's oceans, inhabiting a wide range of environments from shallow coastal waters to the deep sea. Many polynoids are free-living, often found in association with other benthic organisms like sponges, corals, and sea anemones, where they may find shelter or prey. Some species are commensal, living on or within the burrows of other animals, while a few are parasitic.

Polynoididae exhibit a variety of feeding strategies. Some are predators, actively hunting smaller invertebrates, while others are scavengers, feeding on dead organic matter. Detritivory and filter feeding are also observed in certain species. Their segmented bodies are typically flattened, and they possess prominent parapodia with bundles of chaetae (bristles) that aid in movement and respiration. Reproduction in polynoids generally involves external fertilization, with eggs and sperm released into the water column. The family is one of the most speciose within the polychaetes, with numerous genera and hundreds of described species, reflecting their widespread distribution and ecological success.