The Galápagos tortoise complex or Galápagos giant tortoise complex (Chelonoidis nigra and related species) are the largest living species of tortoise. Modern Galápagos tortoises can weigh up to 417 kg (919 lb). Today, giant tortoises exist on only two remote archipelagos: the Galápagos Islands 1000 km due west of mainland Ecuador; and Aldabrachelys gigantea of Aldabra in the Indian Ocean, 700 km east of Tanzania.
The Galápagos tortoises are native to seven of the Galápagos Islands, a volcanic archipelago about 1,000 km (620 mi) west of the Ecuadorian mainland. With lifespans in the wild of over 100 years, it is one of the longest-lived vertebrates. A captive individual lived at least 170 years. Spanish explorers, who discovered the islands in the 16th century, named them after the Spanish galápago, meaning "tortoise".
The Galápagos Islands were discovered in 1535, but first appeared on the maps, of Gerardus Mercator and Abraham Ortelius, around 1570. The islands were named "Insulae de los Galopegos" (Islands of the Tortoises) in reference to the giant tortoises found there.
Initially, the giant tortoises of the Indian Ocean and those from the Galápagos were considered to be the same species. Naturalists thought that sailors had transported the tortoises there. In 1676, the pre-Linnaean authority Claude Perrault referred to both species as Tortue des Indes. In 1783, Johann Gottlob Schneider classified all giant tortoises as Testudo indica ("Indian tortoise"). In 1812, August Friedrich Schweigger named them Testudo gigantea ("gigantic tortoise"). In 1834, André Marie Constant Duméril and Gabriel Bibron classified the Galápagos tortoises as a separate species, which they named Testudo nigrita ("black tortoise").