White-spotted jellyfish in Thailand

A pretty polka-dot jellyfish that divers often see around Koh Tao and Koh Phangan. Its sting is very weak — most people feel nothing.

What it looks like

A domed, translucent bell in light brown, bluish or olive, evenly dotted with white spots. Beneath are eight short oral arms with bunches of long, clear ribbons; there are no tentacles around the rim.

Size: Bell usually 10–30 cm, often smaller in Thailand.

Where and when in Thailand

Found in the Gulf of Thailand and the Andaman Sea; Southeast Asia is part of its native range.

Gulf of Thailand · Andaman Sea

The sting

Usually not felt, or a light prickle.

First aid

📞 Emergency medical services in Thailand: 1669

Rinse with seawater; use a cold pack if the skin is irritated.

Lookalikes

Moon jellyfish — no white spots, four rings in the centre. Rhopilema — larger and firmer with a rough bell.

Did you know

• Microscopic algae live in its tissues, so its colour depends on light.
• Introduced to the Gulf of Mexico, it became invasive there and causes problems for fisheries.

Also called: Australian spotted jellyfish, Phyllorhiza