Galapagos Tortoise is the largest member of the reptile order. The Galapagos Islands have been famed for their giant tortoises ever since their discovery, and these enormous creatures continue to be the best known of the Galapagos Islands animals. The name "Galapagos" originates from the Spanish word "galapago" meaning "saddle," after the saddle-backed tortoises. A Galapagos giant tortoise (Geochelone elephantopus) may weigh up to 250 kg and measure 150 cm over the curve of the carapace.
Together with the Aldabra tortoise of the Seychelles, they are the largest living tortoises: "Some grow to an immense size ... several so large that it required six or eight men to lift them from the ground" (Darwin 1845).
The inhabitants ... state that they can distinguish the tortoises from the different islands; and that they differ not only in size, but also in other characters. Captain Porter has described those from Charles and from the nearest island to it, namely, Hood [Espanola] Island, as having their shells in front thick and turned up like a Spanish saddle, whilst the tortoises from James [Santiago] Island are rounder, blacker, and have a better taste when cooked. (Darwin 1845)
The Galapagos Giant Tortoises are long-living animals with a life span of well over a hundred years. Research has shown that there were probably fourteen races or subspecies of Galapagos Tortoise. Now only ten viable races remain. Tortoises were common on Floreana in the early 1800s but as a result of hunting by whalers, sealers, and settlers, they were extinct by the turn of the twentieth century.
The Santa Fe tortoise is known only from skeletal remains. Only one giant tortoise has ever been found on Fernandina and, aptly named G, A fifteenth race has been proposed for Rabida Island, but it is most unlikely that the one individual discovered there belonged to a different race. It is more likely that it reached the island with man's help as there is evidence that the beach area of Rabida was used as a holding area for tortoises captured elsewhere.
Five of the remaining eleven surviving races are found on the five main volcanoes of Isabela, while the other six are found on James, Santa Cruz, San Cristobal, Pinzon, Espanola, and Pinta, respectively. The five separate volcanoes of Isabela appear to have been isolated enough, as far as tortoises are concerned, to have allowed the formation of distinct races.