Sea nettle (fire jellyfish) in Thailand

Thais call it the “fire jellyfish” for its strong burning sting. It occurs on both sides of the peninsula year-round and often drifts to beaches in numbers. Usually not life-threatening, but painful and slow to settle.

What it looks like

A saucer-shaped, translucent creamy bell with reddish-brown radiating stripes and a scalloped edge. Many long, thin reddish tentacles hang from the rim, with four long frilly oral arms in the centre.

Size: Bell usually 10–20 cm; tentacles can be over a metre long.

Where and when in Thailand

Year-round in the Gulf of Thailand and the Andaman Sea. Large numbers of stings were reported, for example, in Phuket in January and May 2023.

Gulf of Thailand · Andaman Sea · Most often: all year

The sting

Intense burning with red raised welts where tentacles touched; itching and rash can last several days. Rarely, nausea, weakness or headache.

First aid

📞 Emergency medical services in Thailand: 1669

Leave the water, rinse with seawater and remove tentacles; do not rub and do not use fresh water. For pain, use hot water around 45 °C for 20 minutes or a cold pack. If you are not sure which jellyfish stung, pour vinegar as for a box jellyfish sting. Call 1669 for breathing difficulty, facial swelling or stings to the eyes.

Lookalikes

Pelagia (the other species of this family in Thailand) is smaller, pinkish-mauve with warts on the bell and can glow at night. Lion’s mane jellyfish have a dense “mane” of fine tentacles under the bell.

Did you know

• Pelagiidae is one of the five toxic jellyfish groups monitored by Thailand’s Department of Marine and Coastal Resources (DMCR).
• Tentacle fragments torn off by storms can sting on their own, so people sometimes get stung without seeing a jellyfish.

Also called: Sea nettle, Fire jellyfish, Maeng kaphrun fai, Pelagia