Status: Endangered (Geochelone elephantopus); protected by CITES (Geochelone gigantea).
Size: Up to 5 ft. in length; weight up to 600 lbs.
Characteristics: Gentle, slow-moving.
Area: Galapagos islands, the island of Aldabra.
Offspring: 9 to 25 eggs.
· The scientific name Geochelone means “earth tortoise” in Greek.
· The Galapagos Islands are named for these tortoises—galápago means saddle in Spanish and refers to the shell.
· An adult Madagascar tortoise presented as to the Queen of Tonga in the 1770s lived to 1966.
· Giant tortoises sleep approximately 18 hours in a 24-hour period.
· An Aldabra tortoise weighing 305 kilos (672 pounds) in the Seychelles is the world’s largest free-roaming tortoise.
There are two types of Giant Tortoise: the Galapagos tortoise (Geochelone elephantopus) and the Aldabra tortoise (Geochelone gigantea). These tortoises are complete vegetarians, surviving on plants and grasses, as well as fruit. They live mostly on land, but sometime make trips to the water to eat sea vegetation. The larger tortoises can even carry a full-sized adult on their backs. In 1835, Darwin rode these giant tortoises and wrote of his experience: “I frequently got on their backs, and then giving a few raps on the hinder part of their shells, they would rise up and walk away; but I found it very difficult to keep my balance.” Giant tortoises can survive for months without eating or drinking and live ones were taken on ships to provide fresh meat for the sailors. It is estimated that as many as 200,000 tortoises were taken from the Galapagos in the nineteenth century. The sailors also introduced animals such as rats, cats and pigs, who have interfered with the tortoises to such an extent that the tortoises became nearly extinct. The cats and rats ate the tortoises’ eggs, and the pigs were in direct competition with them for vegetation. Seventeen species of giant tortoises living on the islands of the Indian Ocean became extinct, with only the Aldabra island tortoises surviving. The jaws of a giant tortoise have sharp ridges that can literally bite off a human’s finger. Because they’re very gentle, they would never purposely bite, but may misjudge while they’re being offered food by hand.
Although Aldabra tortoises originally came from a group of islands in the Indian Ocean, known as the Seychelles, only the island of Aldabra still has a population of giant tortoises. The Galapagos tortoises inhabit several islands of the Galapagos, off the northwest coast of South America.
Giant tortoises do not breed until they reach at least 20 years of age. The eggs are laid in a warm dry nest and covered with sand. Females usually return every year to the same area to lay their eggs. The white eggs are roughly the size and shape of tennis balls. The hatchlings are extremely small when they emerge, only three inches in length and will continue to grow until they reach 40 years of age. Tortoises are believed to be the longest-lived animals of all, living to between 100 and 200 years of age. They often outlive the scientists who study them.