Invertebrates
Flower Hat Jelly
Olindias formosus · also called flower hat jellyfish
Curling its translucent, colourfully striped tentacles inward like petals around a flattened bell, a flower hat jelly looks almost too delicate to sting, yet delivers a bite painful enough to be felt by anyone careless enough to brush against it.
Overview
The flower hat jelly, Olindias formosus, is a striking coastal jellyfish native to ocean habitat recorded across parts of the Pacific, including waters off Japan and South America. Its distinctive petal-like curled tentacles, faint ultraviolet fluorescence, and painful sting make it one of the most visually memorable and photographed jellyfish species found anywhere along temperate coastlines.
Beauty with a genuine bite
The same striped, petal-curling tentacles that make the flower hat jelly such a popular aquarium and photography subject are also armed with a sting strong enough to cause real discomfort, a reminder that this species’ delicate appearance is no indication of how harmless it actually is.
Status
Not Evaluated, though the species remains a regular seasonal presence in parts of its known coastal range.
Flower Hat Jelly: common questions
Why is it called the flower hat jelly?
This species has translucent tentacles banded with colourful stripes that curl inward toward its bell when not actively feeding, giving the species its distinctive flower-like appearance and inspiring its common name.
Does the flower hat jelly glow in the dark?
Not exactly, this species has tissues that fluoresce faintly under ultraviolet light rather than producing visible light on its own, a feature that has attracted particular interest from aquarium enthusiasts and researchers.
Is the flower hat jelly's sting dangerous to people?
This species delivers a sting capable of causing painful welts and other symptoms in humans, though it is not considered life-threatening under normal circumstances, unlike some more dangerous jellyfish species.
Where is the flower hat jelly typically found?
This species is typically found in temperate and subtropical coastal waters, often near rocky reefs and seagrass beds, particularly in parts of the Pacific Ocean including waters off Japan and South America.