These moon jellies are illuminated by lights in an aquarium. By Luc Viatour
Moon jellies float and swim in currents off the east coast of North America from Maine to Florida. Their translucent, round, umbrella-shaped bodies grow up to 10 inches across. Moon jellies have many short fringe-like tentacles that extend from the edges of their bodies. These tentacles wave in the water and gather tiny plants and animals called plankton that are the main source of food for moon jellies.
Moon jellies are easy to recognize because the center of a moon jelly’s body is decorated with a four-leaf clover shape that is less transparent than the rest of its body. These are the moon jelly’s reproductive organs. While some jellyfish have a painful or poisonous sting, moon jellies are harmless to humans.
Moon jellies occasionally wash up on beaches if they are caught in storm currents or drift too close to shore. When moon jellies or other jellyfish are stranded on the beach, it is easy to see that they are made of a gelatinous or jelly-like substance. This substance is probably what inspired humans to give these bizarre creatures the name of jellyfish.
The center of a moon jelly’s body has a distinctive four-leaf clover pattern. By Cliff from Arlington, Virginia, USA via Wikimedia Commons
This jellyfish was stranded on a beach in Thailand. By sami73 via Wikimedia Commons
The above link plus:
Kaplan, Eugene H. A Field Guide to Southeastern and Caribbean Seashores. Houghton Mifflin Company: Boston, 1988. P. 207.