2022/09/23

Golden jellyfish in Jellyfish Lake on the island of Eil Malk, Palau

© Nature Picture Library/Alamy

If you're lucky enough to see this view through the lens of your diving mask, you must be snorkeling in Jellyfish Lake on the island of Eil Malk in the Pacific island nation of Palau. Golden jellyfish are a subspecies unique to this small lake, on this small island—they're found nowhere else on the planet. Millions of teacup-sized golden jellies inhabit the lake, following the sunlight that nourishes them. Symbiotic algae live inside the jellyfish and provide their hosts with energy as a byproduct of photosynthesis. The more sun the jellies get, the more energy they derive from their hitchhikers. The jellies start the day at the east end of the lake and drift westward until dusk, following the arc of the sun. The saltwater marine lake they live in is one of dozens in the Rock Islands, which Eil Malk is part of. The Rock Islands, declared a UNESCO World Heritage Site in 2012, is a scattering of hundreds of very small, mostly unpopulated limestone islands and islets characterized by their mushroom-like shapes. On Eil Malk, Jellyfish Lake appears to be landlocked, but it's connected to the ocean by three shallow tunnels that bring water into and out of the lake with the tides. Nevertheless, the lake is so isolated from the nearby lagoon that the golden jellies evolved in this micro universe mostly cut off from other food sources and predators. As a result, they've lost their ability to sting. So, if you take a dip—snorkeling is allowed, but not scuba diving—there's no need to keep a polite distance.