The fourth stage is the ephyra. This is the first stage where things start looking like jellyfish. Ephyra generally pulse off the strobila looking like little star shaped jellyfish. They generally eat rotifers or baby brine shrimp. Once they begin to grow bigger they fill in their flesh, so that they appear more round. The also begin to grow a stump, and then full oral arms.
Once the ephyra get bigger they pass into the juvenile stage where their bell measures 1- 2 inches in diameter. At this point they can breed amongst each other. The jellyfish will continue to grow if fed well. Moon jellyfish can get very big in their adult stage, up in the 12 inch diameter region!