This video was taken at Monterey Bay Aquarium
Moon jellyfish, Aurelia labiata belongs to the genus Aurelia and is a cnidarian of the Ulmaridae family.
Distribution: moon jellyfish are found in most seas in Europe, Japan, and Gulf of Mexico as well as in the Pacific Coast of North America. They live in pelagic habitats and they are often washed up on beaches. It is believed that the species migrates toward the surface during the day and downward at night. They are also in the Atlantic and Indian oceans. The optimum temperature for moon jellyfish is 9-19 °C. Although they are more found in warm and tropical waters, they can withstand much colder waters. In regard to salinity, moon jellyfish can also live in brackish waters with as low salt content as 6 g/l.
Description and behavior: their size ranges from 5-40 cm in diameter. They are characterized by their delicate coloration that is usually an opaque whitish, though sometimes with other colors. Moon jellyfishes swim by pulsations of the bell-shaped upper part of the animal. Horizontal swimming is essential to keep the animal near water surface. This way of swimming allows the tentacles to be spread over the largest possible area, in order to better catch food. Moon jellyfish can adapt to the declining of dissolved oxygen in the water through lowering their respiratory rate.
Life cycle: Males and females of moon jellies are sexually distinguished whereas reproduction is sexual. Eggs develop in the female’s recognizable gonads that lie near the bottom of the stomach. Moon jellyfish females carry young larvae on the inner edges of the oral arms. Most jellyfish of this species die after reproducing while some may live a second year.
Feeding behavior: Moon jellyfish is carnivorous and feeds through capturing small organisms. Their foods include small plankton organisms such as mollusks, crustaceans, tunicate larvae, copepods, rotifers, nematodes, young polychaetes, protozoans, diatoms and eggs. These foods collect chiefly on the surface of the animal, where they become entangled in mucus which is then moved to the mouth by cilia. Food is then moved, again by flagellar currents, along eight separate canals that branch off and run into the stomach. When moon jellyfish gets starved, they can shrink dramatically in size while retaining its functionality.
Sources: Wikipedia, Walla Walla University and MarineBio