Chelonia is an order of reptiles that includes all species of turtles, tortoises, and terrapins. These animals are characterized by their bony or cartilaginous shell, which protects them from predators. Chelonia can be found in various habitats, including oceans, rivers, and on land, and they are known for their slow movement and long lifespan. The order Chelonia is divided into two main suborders: Cryptodira, which retract their heads into their shells, and Pleurodira, which bend their necks sideways. Many species of Chelonia are threatened or endangered due to habitat loss, pollution, and hunting, making conservation efforts essential for their survival.