The long "oral arms" of the adult moon jelly, Aurelia aurita, extend from near its mouth, in the center of the bell. Magnus Manske/Wikimedia Commons hide caption

itoggle caption Magnus Manske/Wikimedia Commons

Cannonball jellyfish soak up the sun on a South Carolina beach. Fishermen are now pursuing the pest that used to clog their shrimping nets. Courtesy of Steven Giese hide caption

itoggle caption Courtesy of Steven Giese