The Upside-Down Jellyfish (Cassiopea ornata) is a marine (saltwater) planktonic scyphozoan in the Cassiopeidae family of upside-down jellyfish. It is a cnidarian. It is also known as the Sunbathing Jellyfish. 

It is a photosynthetic jellyfish. It is the only jellyfish that rests with its bell or umbrella on the ocean floor and its tentacles pointing upwards. It does this to receive light so that the symbiotic algae living on it can produce carbohydrates for the jellyfish to use as food for energy.