The upside down jellyfish gets its brownish color from the symbiotic algae that are found within its tissues. This fish gets its name because it rests the top bell portion of its body along the seafloor while it's under parts float up toward the sun. This jellyfish is a farmer and lives off of zooplankton and the food created by the algae. This jellyfish has arms which are actually elaborate frills that contain hundreds of tiny mouth openings that are connected directly to the stomach. When the upside down jellyfish pulses its bells roundish top, zoo plankton are forced into nematocysts on the mouth openings. The upside down jellyfish does not eat their prey in the same manner as other jellyfish as they do not inject their prey directly. Their stinging cells known as nematocysts are controlled by the cnidocil which is equivalent to a grenade launcher. The stinging cells stun or paralyze their prey and the jellyfish begins to ingest their prey with the primary mouth openings that reduce the food into fragments that are passed on to secondary mouths for better digestion.
These unusual jellies are located in forests and shallow lagoons along tropical coasts in Mangrove Forests. Mangrove Forests are constantly under attack by coastal development and suspect farming procedures, making them one of the most threatened ecosystems on the planet. Another major problem for the Mangrove forest is the amount of pollution flowing in that endangers all of the life that live in this rich forest area.
They are a favorite meal for the leatherback sea turtle, that is an endangered species, and the beautiful ocean sunfish. Although their common color is brown they are also found in varying shades of green, blue and white as well. They do have a defense. The stinging cells which are excreted in mucus like material above its body. Unsuspecting swimmers have been stung with this mucus. The stings are known to be extremely itchy with a red rash skin irritation as a result. These are usually nothing more than an irritation to humans but are very effective against most of their predators. The crab family (Dorippidae) is known to pick up this jellyfish and carry on its back using it for its own defense against its own predators.
The upside down jellyfish unlike other jellyfish are only free swimming until there are about 2 cm. in size at which time the Bell inverts dropping them to the bottom of the ocean floor where they spend most of the rest of their adult life. The upside down jellyfish can grow to the size of a small plate, and often looks like a flower, between eight and fourteen inches in diameter. The golden algae that these magnificent beings live on produce the necessary oxygen to help support the necessary respiratory functions of the jellyfish in oxygen poor environments.
Some people are now keeping jellyfish as pets which brings new meaning to the phrase exotic pets.