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Home > Meet Our Animals > Reptiles > Turtles > Galapagos Tortoise
Galapagos Tortoise
Geochelone nigra nigrita
 
Size
Weight Male Galapagos tortoises weigh approximately 500 pounds, and females are about 250 pounds
Conservation Status On the 2007 IUCN Red List of Threatened Species, the Galapagos tortiose is listed as Vulnerable.
Diet In wild, Galapagos tortoises feed mostly on cactus and grass. In the Zoo, they eat commercial mix, salt marsh hay, apples, carrots, kale, iodized salt and mineral powder. Each animal eats 10 pounds of food three times a week.
Geographic Range The Galapagos tortoise is found on the Galapagos Islands in the Pacific Ocean, straddling the equator due west of Ecuador.
Where to find me in the Zoo The Reptile House
Note: Description below should include Longevity, Behavior, and Reproduction information

Tortoises have been on Earth a very long time, dating back at least 200 million years, which means they shared the planet with dinosaurs.  Galapagos tortoises are the largest living tortoises, and they can live 150-200 years.  They live in warm dry regions and cool forest areas on the sides of the volcano.

Not only are the males generally larger than the females, but they also have relatively longer tails. Galapagos tortoises are typically an overall dull black color, and they have paler, pink skin around the head and throat compared to the Aldabra tortoises.

Longevity
In wild, the average lifespan of a Galapagos tortoise can be around 100 years. The oldest known tortoise was presented to the Tongan royal family by Captain Cook in 1777.  Tu'i Malila, as she was called, died of natural causes in 1965, making her a verifiable188 years old.  Another tortoise, Adwaita, who died at the Alipore Zoo in India in 2006, was said to be more than 250 years old.

Reproduction
Toward the end of the wet season in the spring, the female Galapagos tortoise moves to arid lowlands with well-defined nesting sites. To soften the ground, the female urinates on a patch of soil in an open, sunny spot.  The tortoise then lays 2-20 white, hard-shelled, spherical eggs about the size of billiard balls in the hole. She lowers herself over the opening and, by sliding her underside about, raises mud to form a smooth cap almost flush with the surrounding ground. This cap hardens in the sun. The tortoise's eggs hatch after 4-8 months. Hatchlings need rainfall to soften the mud cap so that they can dig their way out of the sealed chamber.

The sex of Galapagos tortoise babies is determined by the incubation temperature of the eggs. Temperatures of less than 28 degrees Celsius produce males and above 29.5 degrees Celsius produce females.

Behavior
Galapagos tortoises are terrestrial and diurnal, or active in the daytime, and very fond of water. They are slow-moving animals, moving only 0.16 miles per hour. They have a dominance hierarchy based on the height to which the tortoise can stretch its head. The Galapagos tortoise's eyesight is extremely poor, so much so that the males will try to mate with almost anything resembling a female, even a large rock. These tortoises spend their day grazing and relaxing in the sun. They also enjoy drinking and wallowing in puddles of water. Nights are usually spent half submerged in mud or water or burrowed in dense brush. This keeps them warm during the cool night hours.

Adaptations
Galapagos tortoises have large scales on their legs that act as protective devices when they withdraw into their shell. When withdrawing, they protect their head by meeting their elbows front. The Galapagos tortoise's foot bones are structured to facilitate walking, and their pillar-like legs help support their weight. 
Their lower jaws are covered by horny ridges with serrated edges that help them cut through tough plants. Galapagos tortoises also have a good sense of smell.

 

Mommy:  Female, born in the wild in the Galapagos Islands.  Her hatch date is unknown but 
     she arrived at the Zoo on April 23, 1932.  She has been at the Zoo longer than any animal
     in the current collection.

Little Girl:  Female, born at the Bermuda Aquarium and Zoo.  It is estimated that she hatched in 
     1940. She is the offspring of tortoises collected from South Albermarle Island during the 
     Townsend expedition of 1928. 

Enrichment

Adoption Information

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According to CITES II, Galapagos tortoises are listed as most restricted and threatened with extinction. The U.S. Endangered Species Act lists Galapagos tortoises as endangered. Galapagos tortoises are threatened by over collecting, introduced animals and increasingly limited ranges. There are only 97 tortoises in the United States population of known subspecies.

A Species Survival Plan breeding program will likely be established for this species soon

Zoo Research

Genetic testing has recently been completed on most of the Galapagos tortoises in the United States. There are six subspecies represented in the United States. Four of these come from the island of Isabella. The Philadelphia Zoo will work with the subspecies (G. n. nigrita) from the island of Santa Cruz, which is the most common subspecies. As the northern most zoo in the United States to have bred Galapagos tortoises, we selected this more common subspecies because the rarer forms are being concentrated in areas that more closely resemble the tortoise's natural environment.

 

Fun Facts

Female Galapagos tortoises bury their eggs in mud that hardens in the sun. Hatchlings need rainfall to soften the soil so that they can dig their way out.

 

Conservation

Introductions

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Sources: (1) Philadelphia Zoo staff (2) IUCN 2007. 2007 IUCN Red List of Threatened Species. www.iucnredlist.org. Downloaded on 04 January 2008.