While most jellies drift with the current, their tentacles pointed downward, this striking jelly lies on its bell on the sea floor, its branching oral arms pointing toward the surface to catch zooplankton as it passes by.
  • Size

    12 to 14 inches (30-36 cm) in diameter
  • Diet

    Zooplankton and plankton
  • Range

    Western Atlantic
  • Habitat

    Coral reefs, sea grass beds and mangrove ecosystems in shallow, warm waters

Physical Characteristics

  • May reach 12 to 14 inches (30-36 cm) in diameter.
  • Length ranges from 8 to 14 inches (20.3 to 35.6 cm).
  • Coloration ranges from green to a gray-blue.
  • Lies on the seafloor with four pairs of branching oral arms that point toward the surface.
  • Upper surface of the jelly’s bell is concave, acting like a suction cup to adhere to the seafloor.
  • No central mouth; uses secondary mouths to ingest prey.

Animal Fact

Upside down jelly’s nourishment comes from the algae in its tissues, called zooxanthellae.

Diet / Feeding

  • Receives most of its nourishment from the symbiotic micro-algae (zooxanthellae) that live in its tissues.
  • Other methods of feeding include filter feeding and using its tentacles to stun and capture prey.
  • Live prey consists mainly of zooplankton and plankton.

Range / Habitat

  • Occurs mainly in the warmer waters of the Western Atlantic, including the Gulf of Mexico, Bermuda and the Caribbean.
  • Found in coral reefs, sea grass beds and mangrove ecosystems in shallow, warm waters.

Reproduction & Growth

  • Male jellies release gametes into the water, and females will take them in for fertilization.
  • Female jellies hold the fertilized eggs in the subumbrella (under side of the bell) until the eggs hatch.
  • Once hatched, the planula become free-swimming until they find a substrate suitable for settling. After settling, the planula develop into polyps.
  • When resources are plentiful, the polyps of this jelly species reproduce asexually by budding to produce sedentary (stationary) polyps.

Conservation Status

  • “Not Evaluated” on the IUCN Red List.

Additional Information

  • Also known as the “mangrove jelly.”
  • Zooxanthellae that live in this jelly’s tissues produce oxygen, allowing it to survive in oxygen-deficient waters.
  • Commonly preyed upon by various species of sea turtle, including the leatherback and loggerhead.


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