What's that buried in the sand in Florida Keys National Marine Sanctuary? A southern stingray! During the day, these rays bury themselves in the sand to hide themselves. At night, they graze the seafloor, using electroreceptors, touch and smell to find their food. Southern stingrays are not aggressive toward humans, but watch out -- these stingrays have a barb at the base of their tail that will cause a painful laceration if stepped on.