Jellyfish are diploblastic meaning they have two layers of true tissue called the endoderm and ectoderm
 with the area in between called the mesoderm. The Moon Jellyfish exists in two different forms, the polyp or the medusa, depending on its stage of the life cycle at the moment. Jellyfish are often medusa form-dominant and during the early phase of their life cycle they start out as a polyp. The body plan of Jellyfish is quite simple because they have no complex organs, no cephalization (no formation of a head), and only consists of one opening, the mouth, which leads
to the gastrovascular cavity, where digestion and respiration occur. A characteristic that sets certain the moon jelly apart from the rest of cnidarians is that they have nematocysts or “stinging cells".
(The picture to the left is property of Sunset Marine Labs, llc © 2012) You can clearly see the gonads (reddish-brown circles) used for primary sex glands and the nerve net is the tan vein-like lines emerging from the center to the edge of the bell. (University of Delaware- CEOE website) This nerve net is the main function as the nervous system for moon jellies since they have very simple body systems. Rhopalium are the main sensory structures used to move the bell inward and outward in the "jetting" motion in order for the Moon Jelly to move in which the picture below to the left shows a clear and rare picture of it (courtesy of Alexander Semenov).  
          The Moon Jelly stays pretty close to the surface of the water. You might not know this, but the moon jelly can only swim horizontally and usually depends on the flow of the current to carry them around. The top of the water also consists of the most abundance of plankton that also rely on the current to carry them. ( It’s tragic sometimes when the current carries these jellies off shore where they are unable to move and then dry up or are attacked by birds or/and turtles.(The picture to the right is property of Joe Burbank.)
          The Moon Jellyfish mainly feeds on plankton, which are tiny organisms that float around the ocean water. Plankton can vary anywhere from tracheal eggs, smalls crustaceans, diatoms, and Protozoans. These jellyfish may seem to be non-threatening, but don’t be mistaken; they are carnivores. A sting from these jellies may not harm humans, but they do have mild stinging nematocysts that they use to paralyze their prey (much smaller than humans are so it goes more damage) and then their mucus coating on the outside of the bell (the round part) entraps them. Since, the moon jellyfish doesn’t have a very complex digestive, circulatory system, or respiration system most of the important functions occur in the gastrovasular cavity. The food is transported to the eight distinctive canals, found uniquely to Aurelia aurita, leading to the gastrovasular cavity for digestion and absorption. (        
           Now that we know what Moon Jellies eat, now we want to know what eats them. The sea turtles and large fish generally eat these jellies. At different stages of their life cycle, they attract different predators. During the polyp stage, the biggest predator is the Coryphella verrucosa, while during the medusa stage the Cyanea capillata is known as the biggest predator (shown in the pictures down below). (Bishops, Andrew et al, 2005.)

(the above pictures along with the picture on the rhopalium are courtesy of Alexander Semenov)
         The moon jellyfish have long been a nuisance for fishermen. A plan of attack to decrease the abundance of moon jelly was proposed by the Japanese Society of Fisheries Science in 2010 to make Aurelia aurita a main food source for filefish or other high selling fish in the market. Filefish were separated into four different feeding types in order to observed body weight and length between these different feeding types in order to conclude if the different food sources has any effect on the fish. These scientists found that feeding only moon jellyfish or adding the moon jellyfish into the diet plan of these filefishes has increase their growth rather than just feeding on krill alone. These experiments show much promise, but need more extensive research in order to address the issue of the mass abundance of the moon jellies and their involvement with the bay areas. (Miyajima, al. 2011.)