A turtle is a reptile that can live either on land or in the water and are distinguished from other reptiles by its bony shells. There are more than 400 known turtle species in the world that are typically divided into several different categories based on the type of neck and the primary habitat. Turtle species can be classified as side necked Pleurodiras or hidden necked Cryptodiras. Additionally, turtle species are categorized as semi terrestrial (land and water dwelling) or aquatic (water dwelling). Aquatic turtles live either in fresh or salt water. Small turtles, particularity Russian tortoises and Red-eared sliders, are commonly kept as pets in the United States.
The difference between the Pleurodira and Cryptodira turtle species involves how the reptile defends itself. A Pleurodira turtles will move its neck and head to one side of its bodies, hiding under the outer lip of their shells. In contrast, a Cryptodira turtle will retract its head and neck back into its shell when threatened. Pleurodira turtles are less common and are found in Australia, South America and regions of Africa. Crytodira turtles include pig-nosed turtles, river turtles, pond turtles, tortoises, softshell turtles and leatherback turtles among other species.
Terrestrial turtle species live both on land and in the water. These turtles generally prefer marsh and swamp land with easy access to mud and water. Box turtles are a common terrestrial turtle species that have dark domed shells and are omnivorous. These turtles live in mossy areas, can grow to around 6 inches long (15 cm), are territorial and hibernate in the winter. Mud turtles are semi terrestrial and inhabit sandy and muddy terrain where they eat insects and tadpoles.
Aquatic turtle species live in fresh or salt water environments. The various species of slider turtles live in swamps with a lot of vegetation and in small ponds where they dig in mud. Sliders will eat vegetables such as lettuce as well as small fish. Painted turtles boast red or yellow stripes and can grow to over 10 inches long (25 cm). Like slider turtles, painted turtles are omnivorous and will eat lettuce, fish and even chicken. Painted turtles prefer to sleep in the water, but will occasionally sun on a rock or a log.
Sea turtles live in all oceans with the exception of the Arctic. Although they breathe air, sea turtles prefer to remain fully submerged in water and are solitary except when breeding. Some sea turtles, such as the black sea turtle, eat a vegetarian diet while the leatherback is carnivorous and eats jellyfish and other small animals with soft bodies. Sea turtles generally migrate thousands of miles each year and can live to be 80 years old.