What do you call an unusual jellyfish that spends much of it’s time upside-down, soaking up the sun’s rays on the ocean floor? Well, the “upside-down jellyfish,” of course.


  • When snorkeling in the coastal waters of South Florida, you may come across large groups of upside-down jellyfish carpeting the floor of the ocean. When it needs to move around, the upside-down jelly fish can be seen swimming right-side up, pulsating its bell for propulsion like any regular jellyfish.


  • The upside-down jellyfish gets its name, however, because a lot of the time it can be found resting on the bottom with its tentacles pointing upwards towards the water’s surface. Why, you might ask, does it spend so much time resting upside down? Well the answer has to do with the symbiotic algae that live within the tissues of its tentacles. Because these algae (called “zooxanthellae,” as we just learned) require sunlight to photosynthesize, the upside-down jellyfish spends most of it’s time inverted so that the sunlight from above can shine upon its algae-filled tissues. So although it does filter-feed and catch small prey with its stinging cells, the upside-down jellyfish is often content resting, and letting the algae do the hard part. Why work more than you have to?!