Moon jellies are translucent jellyfish with short tentacles and four noticeable round reproductive organs (gonads) on the bell. They can grow up to 12 inches with some reaching 18 inches. Their bodies are made up of 95% water and they are equipped with a mild sting. Moon jellies are found around the world and are commonly seen in coastal waters and harbors. They are passive drifters using the currents to move and catch tiny zooplankton and small fish in their tentacles.