Freshwater jellyfish can occur in virtually any type of waterbody if conditions allow, including lakes, ponds, quarries, reservoirs, and even sluggish streams and rivers. Only one species of freshwater jellyfish (Craspedacusta sowerbyi) occurs in North America, but this species is found virtually worldwide. They have a clear or translucent white bell-shaped body about the size of a dime or nickel. Unlike some marine jellyfish, the freshwater jellyfish does not pose a hazard to swimmers. They are typically found in late summer during August and September. Their appearance is sporadic and unpredictable. Individuals become apparent as they rise to the water surface in afternoon to early evening, especially on clear and warm days in calm water.
(Description courtesy of the Indiana Department of Natural Resources)
Video courtesy of Heath Frazier