Blue button in Thailand

A small floating disc with a blue fringe that wind sometimes pushes onto beaches in large numbers. It is not a true jellyfish but a relative of the bluebottle. The sting is usually mild, though it can burn.

What it looks like

A flat, round golden-brown disc with rings, surrounded by bright blue or turquoise tentacles tipped with dark stinging knobs.

Size: Disc up to about 3 cm across.

Where and when in Thailand

Drifts in the open sea and is blown ashore on both coasts. In 2026, for example, swarms were reported in the Similan Islands, where swimming zones were temporarily closed.

Andaman Sea · Gulf of Thailand

The sting

Burning and prickling with redness or an itchy rash where it touched. Sensitive skin and eyes react more.

First aid

📞 Emergency medical services in Thailand: 1669

Rinse with seawater and remove any tentacle pieces without rubbing. For pain, use a cold pack or hot water around 45 °C. See a doctor if it gets into the eyes or a strong rash develops.

Lookalikes

By-the-wind sailor — a similar blue disc but with a clear triangular sail. Bluebottle — an inflated float with long tentacles.

Did you know

• A blue button is a colony of polyps: some catch food, others digest it, others reproduce.
• Some juvenile fish shelter beneath blue buttons.

Also called: Blue button jelly, Porpita