Galapagos Giant Tortoise (Geochelone nigra)


Class: Reptilia
Order: Testudines
Family:    Testudinidae 
Size:    Length: Up to 5 feet (1.5 m) 
Weight: Up to 600 pounds (272 kg)
Diet: Plants, grasses and fruit
Distribution: Galapagos Islands
Young:  9 to 25 eggs, up to 4 times per year
Animal Predators:  Unknown
IUCN Status: Vulnerable
Terms: No special terms
Lifespan: 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



·       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.

·       Giant tortoises sleep approximately 18 hours in a 24-hour period.

·       An Aldabra giant tortoise weighing 305 kilos (672 pounds) in the Seychelles is the world’s largest free-roaming tortoise.

·       Harriet, a giant tortoise at Steve Irwin’s Australia zoo, was originally removed from the Galapagos by Charles Darwin in 1835. 



Giant tortoises have a thick, black shell and rough, black skin. Males are usually larger than females. The upper part of their shell is called the carapace and Galapagos tortoises have two different kinds—the “saddleback” and the “dome-shaped.” Saddleback tortoises are found on the islands where there are arid places, like Espanola and Pinzon, and tend to be more aggressive. Dome-shaped tortoises live in areas that have more moisture, with green vegetation and plenty of water and shade. 



Galapagos tortoises inhabit several islands of the Galapagos, off the northwest coast of South America. They live mostly on land, but sometimes make trips to the water to eat sea vegetation. 


Feeding Habits

These tortoises are complete vegetarians, surviving on plants and grasses, as well as fruit. Galapagos tortoises have a good sense of smell, and smell all of their food before consuming it. 



Giant tortoises do not breed until they are 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 after three to eight months of incubation, but continue to grow until they reach 40 years of age. 



Large giant tortoises can carry a full-sized adult on their back. In 1835, Charles 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. The jaws of a giant tortoise have sharp ridges that can literally bite off a human’s finger. Because they are very gentle, they would never purposely bite, but may misjudge while being offered food by hand.



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, which have interfered with the tortoises to such an extent that the tortoises nearly became extinct. The cats and rats ate the tortoises’ eggs, and the pigs were in direct competition with them for vegetation. Today there are an estimated 15,000 Galapagos giant tortoises. 



Giant Tortoise Wildlife Fact File, IM Pub, US

The Crocodile Hunter, Steve and Terri Irwin; Dutton: A Division of Penguin Putnam, 2001