Chrysaora plocamia, the South American sea nettle, is a species of jellyfish from the family Pelagiidae. It is found from the Pacific coast of Peru, south along Chile's coast to Tierra del Fuego, and north along the Atlantic coast of Argentina, with a few records from Uruguay. Despite its common name, it is not the only sea nettle in South America. For example, C. lactea is another type of sea nettle in this region. Historically, C. plocamia was often confused with C. hysoscella, a species now known to be restricted to the northeast Atlantic. C. plocamia is a large jellyfish, up to 1 m (3 ft 3 in) in bell diameter, although most mature individuals only are 25–40 cm (10–16 in).

Description Chrysaora plocamia, like many other sea nettles or jellyfish in the phylum Cnidaria, gets its name from its sting resembling a bee or nettle bush. The scientific name of these cnidarians comes from the son of Poseidon, Chrysaor. The specific epithet of C. plocamia is derived from the Ancient Greek plókamos, meaning "tress" or "braid of hair". The South American Sea Nettle is known for its red-brown bell, long, spiraling arms, and thin tentacles.