Jellyfish Lake in Palau is a unique place on earth where several coincidences have made it the perfect environment for millions of jellyfish to evolve their own species – perfectly adapted and isolated from the rest of the world.

JELLYFISH LAKE     © Sarosh Jacob

Around 12 000 years ago, as the water level was decreasing, the lake was formed as a natural basin of rocks and lime stones with only a few living creatures trapped inside it.

The rocks and trees that surround it have formed conditions which restrict the mixing of water vertically even though the lake has a connection to the sea via three tunnels. Those do not lead to water movement because they are located near the surface. These conditions and the tropical temperatures have made the lake one of a few saline meromictic lakes that consist of two layers of water that never intermix.
The Jellyfish have adapted to these conditions by forming a new species that to this day only exists in Jellyfish Lake:

The Golden Jellyfish.

This Jellyfish has changed its appearance and lost its stinging ability because it is almost useless in an isolated environment. Instead, it relies on the zooxanthellae, algae, that live symbiotically in their tissues and provide their hosts with energy as a byproduct of their photosynthesis. Therefore they are dependent on sunlight which results in the Jellies migrating with the movement of the sun every day from one side of the lake to the other.

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