Upside-Down Jelly

(Cassiopea xamachana)

  • Animal Type


  • Exhibits

    Jellies Invasion

  • Range

    Atlantic Ocean

    Pacific Ocean


This jelly does not move or look like a typical jelly; in fact, it looks more like a flower blooming on the seafloor. Its bell is flat and shaped like a saucer. Coloration can vary, but upside-down jellies are typically greenish to gray-blue, and they have four pairs of elaborately branched but unfused oral arms.

A Note from the Caretaker

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

Quick Facts

Did you know that, instead of swimming or floating, the upside-down jelly spends its life pulsing on its bell in shallow, sunlit water.

The Caribbean, Hawaii and Florida

The upside-down jelly eats zooplankton.

The bell of the upside-down jelly can be up to 14 inches wide, about the size of a serving plate.

Jellyfish populations were once kept in check by predators like sea turtles and jelly-eating marine animals. However, due to ongoing reductions in the populations of their predators, many jellyfish species populations are growing at alarming rates.

Sea turtles and other jelly-eating animals, such as tuna, sunfish, butterfish and spiny dogfish, generally keep jelly populations in balance. All seven species of sea turtles include jellyfish 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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