Moon jellyfish (Aurelia aurita) undulating at a local zoo.  Moon jellies feed by moving slowly and catching unsuspecting prey in their wispy tentacles, which then contract in a corkscrew motion to bring the prey in to the body.  While moon jellies in zoos have been known to live for several years, those in the wild usually live only 6 months, often dying due to being exhausted from reproduction and thus contracting bacterial infections from warming waters.