All members of the order Turtles, commonly known as turtles, are the oldest living reptiles. It is characterized by a very strong carapace on its body. When attacked, the turtle can retract its head, tail and limbs into the shell. Most turtles are carnivorous. Turtles can usually live on land and in water, and some can also live in the sea for a long time. Living turtle. Turtles are also long-lived animals, with some living for more than a hundred years in the natural environment.