Why do turtles live so long? Apparently, it may have something to do with a slow metabolism which means that turtles need fewer calories than other animals of similar size.
Their longevity may also be due to them being poikilothermic which means their bodies can function at a wide range of temperatures. Such biological phenomena allow turtles to be less susceptible to stress from temperature as well as reactive oxygen species; a deadly reaction when over accumulated.
It is also believed that telomerase, the enzyme responsible for keeping the caps of chromosomes intact, is produced in great amounts by turtles, ultimately increasing their longevity.