Chrysaora fuscescens

The Pacific sea nettle is the yellowish to reddish-brown jelly with long, frilly mouth-arms, found in coastal waters from Alaska to California and across to Japan and the Bering Sea. Its bell can reach about 45 cm, and the ruffled mouth-arms trail 12 to 15 feet below it. Not every jelly stings, but this one does: its tentacles and mouth-arms are covered with stinging cells, so admire it from a boat or through aquarium glass rather than in the water. Sea nettles are abundant enough to matter in the plankton food chain, and changes people make to coastal waters are linked to more frequent jelly blooms.