Nereis, which belongs to Annelida, polychaeta, Animalia and Nereistidae in taxonomy, are commonly known as sea worms, sea maggots, sea centipedes and sea leeches. There are about 8 species of Nereis in China, and the economic species and varieties used for breeding mainly include: Nereis japonica, Perinereis spinulosa, Perinereis bidentata and so on. They like to live in the sand and mud in the coastal mudflats, intertidal zone and subtidal zone where fresh water flows in. Larvae feed on plankton and adults feed on humus. Nereis has high nutritional value and is widely used in aquaculture.