Moon Jelly Aurelia aurita The Moon Jelly is translucent, usually about 25-40 cm across and can be recognized by its four horseshoe-shaped gonads that are easily seen through the top of the bell. It is capable of only limited motion; like other jellies it primarily drifts with the current even when it is swimming. It feeds by collecting crustaceans, fish fry, plankton, mollusks and other sea jellies with its mucusy bell and nematocyst-laden tentacles and bringing the prey into its body for digestion.