Mangrove box jellyfish (Tripedalia) in Thailand
Tripedalia spp. · Family: Tripedaliidae · In Thai: แมงกะพรุนกล่องขนาดเล็ก
A tiny, fingernail-sized box jellyfish of mangroves and sheltered bays. Its sting is usually mild. By size and shape it is easy to confuse with young dangerous box jellyfish.
What it looks like
A clear, sometimes golden cube-shaped bell. Each corner has three (two in T. binata) small arms, each with a single thin tentacle.
Size: Bell about 1 cm.
Where and when in Thailand
Lives in mangrove channels, lagoons and calm shallow water, often near the surface in sunlight. Both species appear in the list of jellyfish from Thai waters.
Gulf of Thailand · Andaman Sea
The sting
Usually a light prickle or burn that fades on its own. People with sensitive skin may get an itchy rash.
First aid
📞 Emergency medical services in Thailand: 1669
Since a small box jellyfish cannot be identified by eye, treat it as a box jellyfish sting: vinegar for at least 30 seconds, no rubbing, no fresh water, then a cold pack. Call 1669 if pain grows or breathlessness, a racing heart or back pain appear.
Lookalikes
Young Chironex and Morbakka can also be small. The key difference is several separate tentacles per corner, rather than one or a bundle from a single arm.
Did you know
- Tripedalia has 24 eyes and uses them to navigate between mangrove roots.
- Males pass sperm to females in packets, unusual among jellyfish.
Also called: Mangrove box jelly, Tripedalia cystophora, Tripedalia binata
Full first-aid guide →
Report jellyfish →
Sources
- Osathanunkul et al. (2022). Distinguishing venomous jellyfish species via HRM analysis (Table 1: jellyfish of Thai waters, DMCR data). Front. Mar. Sci.
- Ekins et al. (2014). First record of Tripedalia cystophora in Australia, the Indian Ocean, Thailand and Grand Bahama
- Monterey Bay Aquarium — Mangrove box jelly
- ANZCOR Guideline 9.4.5 — First Aid Management of Marine Envenomation
Other jellyfish of Thailand
Thai box jellyfish (Chironex)
Chiropsoides box jellyfish
Morbakka (single-tentacle box jellyfish)
Portuguese man o’ war (bluebottle)
Sea nettle (fire jellyfish)
Lion’s mane jellyfish
Questions and answers
Is the mangrove box jellyfish (tripedalia) dangerous?
Moderate sting. Usually a light prickle or burn that fades on its own. People with sensitive skin may get an itchy rash.
Where in Thailand does the mangrove box jellyfish (tripedalia) occur?
Lives in mangrove channels, lagoons and calm shallow water, often near the surface in sunlight. Both species appear in the list of jellyfish from Thai waters.
What to do if stung?
Since a small box jellyfish cannot be identified by eye, treat it as a box jellyfish sting: vinegar for at least 30 seconds, no rubbing, no fresh water, then a cold pack. Call 1669 if pain grows or breathlessness, a racing heart or back pain appear.