by Warren Fahy
Each world covered in this series looks at a different isolated ecosystem, each one a unique pattern of exotic life that has exploded in slow motion over millions of years with the sheer power of nature’s variation, resulting in the picture that we see today from our brief vantage point. In many ways, the Earth is a like a galaxy of alien worlds that have branched apart in unique directions. Far from being a small world, we live on a planet of many worlds, so many, in fact, that none of us could ever live long enough to explore them all (except for David Attenborough).
This week, we will take a look at Jellyfish Lake (Ongeim'l Tketau), an inland lake on Eil Malk island in the Rock Islands of the nation of Palau. Connected to the sea through a subterranean passage, this habitat, and its inhabitants, are out of an Edgar Rice Burroughs science fiction novel.
While the lower level of the lake is saltwater and deprived of oxygen, the upper level is much fresher and oxygenated. The levels don’t mix, which is very rare for a marine lake. Three tunnels in the island’s limestone foundation allow saltwater in but have managed to block most outside species.
After only 11,000 years of isolation, two species of endemic jellyfish have evolved to live in the lake and a handful of other nearby lakes on the island of Palau that are off limits to snorkelers. One of the Jellyfish species has developed a cyclic migration as millions move in unison from one end of the lake to the other, synchronized to the sun.
Jellyfish Lake is now a destination for humans who want to dive into an alien world with the luckily harmless cnidarians...