Stingless Jellyfish (Ubur-ubur tak menyengat)

Mastigias-type

Stingless Jellyfish habitat

Lake Mariona hosts dense populations of stingless jellyfish that pulse slowly through sunlit water. These Mastigias-type jellyfish have lost most of their sting through isolation in the lake, making it possible to swim among thousands of them safely.

HabitatIsolated marine lakes and enclosed lagoons
DietPlankton plus symbiotic algae
SizeUsually 8-10 cm bell diameter
BehaviorSlow drifters; gather in sunlit water; daily movements

Where you might see it

Lake Mariona, an enclosed marine lake on Kadidiri, is the only reliable place to see them in the Togeans. Populations fluctuate with seasons and conditions, but on good days the lake holds thousands, concentrated in the sunlit upper layers.

How to spot it

Enter the lake slowly and wait for your eyes to adjust — amber-colored bells will appear pulsing gently in the water column. They concentrate in sunny patches, following the light throughout the day. Move carefully to avoid collisions.

Responsible Encounter Guidelines

  • Don't touch or scoop them — even gentle handling damages their delicate tissue.
  • Swim without fins to reduce injury risk — float and move slowly through the lake.
  • Skip sunscreen and lotions before entering — oils harm the enclosed ecosystem.
  • No soap, shampoo, or other products on your skin — the lake is chemically sensitive.

Gallery

Stingless Jellyfish gallery 1
Stingless Jellyfish gallery 2

Conservation Status

Highly sensitive to pollution and temperature shifts in enclosed lake ecosystems.