Upside-Down Jellyfish
Upside-Down Jellyfish Upside-Down Jellyfish Upside-Down Jellyfish Upside-Down Jellyfish

Upside-Down Jelly, Cassiopea xamachana

This jelly does not look like the typical jelly, appearing as a flower on the seafloor. The bell is flat and shaped like a saucer. Color can vary, but is typically greenish to gray-blue. It has four pairs of elaborately branched but unfused oral arms.

Did You Know?

Instead of swimming, this jelly spends its life pulsing upside-down in shallow, sunlit water.




Bell can be up to 14 inches wide, about the size of a serving plate


Caribbean, Hawaii, and Florida

Population Status

In the past, jelly populations were kept in check by predators like sea turtles and jelly-eating fish. Due to the reduction of their predators, jelly populations are growing at alarming rates.


Sea turtles and other jelly-eating animals, such as tuna, sunfish, butterfish, and spiny dogfish, keep the jelly populations in balance. All seven species of sea turtles include them in their diets. The largest sea turtle species, the leatherback, depends on jellies for food. Because jellies are more than 90% water and an adult leatherback can weigh more than 2,000 pounds, one turtle can consume a lot of jellies.

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A Note From the Caretaker

The different colors seen in each upside-down jelly come from the uptake of algae from the water sources in which the jelly was raised. Aquarists can distinguish between wild jellies (muddy brown in color) and captive-cultured jellies (blue, black, bright white, green, or purple) reared at an aquarium.