JELLYFISH LAKE TOURS

Jellyfish Lake is one of about 70 marine lakes found within the Rock Islands of Palau. This is a marine basin surrounded by a limestone island but connected to the inner lagoon by small and large channels or tunnels that course their ways through the rock. Some basins are connected to the lagoon by relatively wide channels that boats can navigate and others are almost completely isolated, connected only through microscopic cracks and fissures through the limestone

There are actually several marine basins in Palau that support large populations of jellyfish, though only the largest of these is open to the public. Many of the marine basins cannot be visited without special permission from Koror State because of ecological balance considerations.

These basins are “closed” ecosystems because of their relative isolation within the Rock Islands, meaning there is little connection between environments other than the saline water pushed by tides seeping slowly through the islands' rock formations. These result in complex ecosystems that are fascinating subjects for ecological studies. The more isolated basins feature organisms that have successfully evolved to tailor-fit their particular habitat, allowing them to grow and reproduce optimally.

The Mastigias species of jellyfish is a perfect example. These jellyfish (or, their larvae) wandered into their particular marine basins thousands of years ago through fissures in the rock formation of islands in the islands. Once the jellyfish populated the basin they became isolated from their ancestral counterparts, Mastigias papua. Receiving little or no genetic exchange with their ancestors, the jellyfish in the basin adapted to a completely new environment devoid of predators. As a result of not being required to defend themselves, they evolved into having a drastically reduced number of nematocysts, or stinging cells. In turn these make them harmless to humans, resulting in a one-of-a-kind experience wherein people can swim among thousands of them and not get stung, hurt or irritated.