A sea turtle's lifespan ranges from 80 to 100 years. It is difficult to determine the exact age of a sea turtle from physical appearance. Biologists derive age estimates from the maturity and reproductive status of the turtle.
Depending on the species, sea turtles take between 15 to 50 years to reach maturity. Once mature, they can reproduce for at least another 10 years.
Sea turtles are ancient creatures. The seven existing species have been around for about 110 million years. Sea turtles once numbered in the millions, but only a fraction remain due to poaching and habitat destruction. Determining the exact remaining number is difficult since males never return to shore after they hatch. All sea turtle species are listed as endangered.