the two largest species of reptiles of the family Testudinidae (land tortoises). The species Geochelone elephantopus inhabits the Galápagos Islands. (The species was formerly subdivided into a number of species, which are now considered subspecies.) The carapace is up to 1 m long (sometimes as much as 1.5 m) and more than 0.5 m high. The tortoises weigh up to 100 kg; exceptionally large individuals may weigh as much as 400 kg. The males are larger than the females. The only remaining members of the species G. gigantea are found on the Aldabra Islands in the Indian Ocean.
Up until the 18th century several species of giant tortoises were distributed on the islands of the Pacific and Indian oceans. Beginning in the 17th century the tortoises were subjected to extensive slaughtering by man, who used the meat, the eggs, and the fat (to make a valuable oil). They were later preyed upon by mammals brought to the islands by man.