Fauna
Invertebrate

Flower Hat Jelly

Olindias formosus

Also known as Flower Hat Jellyfish

Flower hat jellies drift like ornate, translucent lanterns through the coastal waters of the northwestern Pacific. By day, these striking hydrozoans anchor themselves to rocks and algae on the seafloor, but at night they ascend to hunt small fish with their brilliant, multicolored tentacles. Their highly distinctive bell features pinstripes and a crown of fluorescent pink and green tips that lure prey.

BioluminescentNocturnalMarine
Flower Hat Jelly reference
Fred Hsu (Wikipedia:User:Fredhsu on en.wikipedia) / CC BY-SA 3.0 · cc-by-sa
—observations
—countries
—peak records
Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & preySmall fish, Copepods, Larval crustaceans
Predators
  • Sea turtles
  • Large fish
  • Other jellyfish
ThreatsCoastal development, marine pollution, and climate change
HabitatsCoastal waters, rocky reefs, and seagrass beds
Life span4 to 6 months
Classification
  1. FamilyOlindiidae
  2. SpeciesOlindias formosus
Range & activity
Range data is not available yet.
Safe observation
Interaction riskVery high
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is very high
Possesses a painful sting; avoid touching tentacles and observe from a safe distance.
Why it is dangerous
Sting delivers a painful neurotoxin that causes severe burning, skin rash, and localized swelling.
How to recognize a risky encounter
Recognizable by the translucent, pinstriped bell and a crown of bright pink, purple, and green tentacles.
What to do
Never touch live or dead specimens; seek immediate medical attention if stung.
Responsible observation
  • Night diving: Look for them rising from the seafloor into the water column after sunset.
  • Keep distance: Maintain a respectful distance to avoid drifting into their trailing tentacles.
  • Look for fluorescence: Use a blue light or UV torch to see their vibrant pink and green tips glow.
Related species
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