Tortoises or land turtles are land-dwelling reptiles of the family of Testudinidae, order Testudines. Like their marine cousins, the sea turtles, tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The tortoise has both an endoskeleton and an exoskeleton. Tortoises can vary in size from a few centimetres to two metres. Tortoises tend to be diurnal animals with tendencies to be crepuscular depending on the ambient temperatures. They are generally reclusive animals. The biggest operational difference between tortoises and turtles is that tortoises are unable to swim; indeed, they cannot float, whereas turtles can.---------------The box turtle is one of several species of turtles. It can refer to either those of the genera Cuora or Pyxidea, which are the Asian box turtles, or more commonly to species of the genus Terrapene, the North American box turtles. They are largely chraacterised by having a domed shell, which is hinged at the bottom, allowing the animal to close its shell tightly to escape predators. Otherwise the two genera are very different in habitat, behaviour, and appearance, and as such are not even classified in the same family. Even though box turtles have become very popular pets, their needs in captivity are complex and the capture of turtles can have serious detrimental effects on the wild population. The average life span of box turtles is 40 years. However, it is possible for a box turtle to live for over 100 years.