Freshwater jellyfish may sound like an oxymoron—because jellyfish live in the ocean, right? Not all of them. Craspedacusta sowerbii , also called the peach blossom jellyfish, thrives in rivers, lakes and even gravel pits.

Originally from the Yangtze River valley in China, these bell-shaped jellyfish have spread across every continent except Antarctica. They’re considered nonindigenous in most places and often turn up in the U.S. Geological Survey’s Nonindigenous Aquatic Species Database.

They’re small—usually less than an inch (about 2 cm) in diameter—with a translucent body that can have a whitish or greenish tinge. Long tentacles trail from the edge, armed with stinging cells to capture prey like zooplankton. But don’t worry: They’re too weak to penetrate human skin.

Life Cycle of

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