Tortoise Tortoise, common name for members of a family of turtles that live entirely on land.

Tortoise Tortoise, common name for members of a family of turtles that live entirely on land. Tortoises are slow-moving animals known for their long life spans, which in some instances may exceed 150 years. There are 41 species of tortoises. Tortoises inhabit all of the world's landmasses except for Australia and Antarctica. The greatest numbers of tortoises are found in the tropical regions of Africa, South America, and Asia. Most tortoises live in dry environments, such as deserts and savannas, although some species prefer moist habitats, such as rain forests and woodlands. Tortoises range in size from the Madagascan spider tortoise, which at maturity is about 10 cm (4 in) long, to the Aldabra giant tortoise, which can grow to about 1.4 m (4.5 ft) long and weigh up to 254 kg (560 lb). Tortoises are protected by heavy shells composed of an inner, bony layer and an outer layer made of horny plates. Among most tortoises, the shell has a domelike shape. This shape makes it difficult for predators to fit their jaws around the shell and crush it. In some species, the shell has flexible hinges that the tortoise uses to close off the openings through which it withdraws its head, limbs, and tail. Tortoises have strong, thick legs that can carry the weight of their heavy shells. A tortoise walks slowly when it moves at all; it may remain motionless for hours and then move at a speed of only 0.2 km/h (about 0.1 mph). Some tortoises, such as the gopher tortoise found in the southern United States and northern Mexico, have flattened forelimbs that help them to dig underground burrows. The skin on a tortoise's head, tail, and limbs is covered with horny scales, which help prevent the inner body tissues from drying out. Most tortoises are herbivores, or plant eaters. Like all turtles, tortoises have toothless jaws that are covered by horny ridges. Tortoises use their jaws to bite off sections of plants. Some species have a diet that includes a mixture of vegetation, small animals such as insects and worms, and the carcasses of larger animals. Their inability to move quickly prevents tortoises from chasing after prey. Mating among tortoises commonly begins with courtship behavior by a male, who circles a female while bobbing his head. In some instances, the male may bite the female's shell and legs. The male next mounts the female to mate her. Some giant tortoises bellow loudly during this process. Female tortoises lay their eggs in underground nests. Depending on the species, the time required for incubation may be about two months or more than a year. In some species, such as the Burmese brown tortoise, the female tortoises remain near their nests for several days to defend their eggs against predators. Once hatched, however, young tortoises fend for themselves without help from their parents. Many tortoise species are endangered because of human activities. Humans use the meat and eggs of tortoises for food and destroy or alter tortoises' natural environments. The giant tortoises of the Galápagos Islands are among the world's most threatened tortoises. Huge numbers of these tortoises were killed by the crews of whaling ships during the early 19th century. Today, these giant tortoises are threatened by many of the animals that humans have introduced to the Galápagos Islands. These animals include pigs that eat tortoise eggs, rats that eat hatchlings, and goats that eat vegetation that tortoises rely on for food. The Galápagos giant tortoises are now legally protected under the laws of Ecuador. Scientific classification: Tortoises make up the family Testudinidae in the order Testudines. The Madagascan spider tortoise is classified as Pyxis arachnoides, and the Albadra giant tortoise is Geochelone gigantea. The Burmese brown tortoise is Geochelone emys. The gopher tortoise is classified as Gopherus polyphemus, and the Galápagos giant tortoise is Geochelone elephantopus. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.