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Aquarium of the Pacific - Online Learning Center - Species Print Sheet

Conservation Status:  Data deficient

Aquatic SpeciesFlower Hat Jelly

Olindias formosus CnidariansSea jellies

flower hat jelly
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Species In-Depth | Print full entry

At the Aquarium

Flower hat jellies are on display in the Northern Pacific Gallery across from the Diving Birds exhibit.

Geographic Distribution

Flower hat jellies are found off southern Japan, Argentina, and Brazil.


These jellies typically live near the ocean floor close to kelp or seagrass.

Physical Characteristics

Flower hat jellies have a translucent bell with dark, opaque pinstripes radiating from the top center to the edge. Lustrous, multicolored, fluorescent- tipped tentacles trail from the bell, with others coiled up close to their bodies, making them appear short. They appear to light up like fireworks under a black light.


This species’ bell size can be up to 6 inches (15 centimeters) wide.


These jellies feed on small fish captured with their tentacles.


Because these jellies are bottom dwellers, it has been difficult to observe them and learn about their life cycle. It is not known what triggers gamete release and how fertilized gametes develop into larvae and then stalk-like polyps. Typically jelly larvae will attach themselves to a solid substrate and then become polyps. It was recently discovered that this jelly’s polyp is unusual, as it has one very active tentacle, and the polyps have been observed under black light in some aquarium exhibits budding off new jelly medusae.


This is a nocturnal species, remaining on or near the sea bed during the day.


This jelly lives for four to six months.


This species has not been evaluated by the International Union for Conservation of Nature. Flower hat jelly blooms in Brazil have interfered with shrimp fishing by clogging the nets and driving away the shrimp.