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Galápagos Giant Tortoises (Chelonoidis spp.) Fact Sheet, 2017


Image Credit: © San Diego Zoo Global. All Rights Reserved. 

TaxonomyPhysical Characteristics

Describer: Quoy and Gaimard (1828) (for Testudo nigra)

Kingdom: Animalia

Phylum: Chordata

Class: Reptilia

Order: Testudines

Family: Testudinidae

Genus: Chelonoidis

Species:

  • Extant: C. becki, C. chathamensis, C. darwini, C. donfaustoi, C. duncanensis, C. guntheri, C. hoodensis, C. microphyes, C. porteri, C. vandenburghi, C. vicina
  • Extinct: C. abingdonii, C. elephantopus, C. phantastica, undescribed species

Body Weight:
Varies by shell shape and sex (see Physical Characteristics)
Hatchlings: 70-90 g (2.5-3.2 oz)

Body Length: Up to 1.2-1.8 m (4-6 ft)

Appearance: Among the largest terrestrial reptiles. Long neck. Robust limbs. Bony plates on carapace and forelimbs. Jaws with sharp edges for tearing vegetation.

Carapace (upper shell): Variety of carapace shapes. Round "domed" type, flatter "saddleback" type with high anterior opening; some "intermediate" shapes also described.

Sexual Dimorphism: Males have concave plastron (lower shell). Males up to 2-3 times larger than females. Size difference particularly pronounced in saddlebacked species.

Distribution & StatusBehavior & Ecology

Range: Galápagos Islands, west of Ecuador.

Habitat: Found in diverse habitats.
Saddleback carapace types found on small, dry islands with low elevation and sparse resources.
Domed carapace types and some saddleback carapace types found on larger, wetter islands with higher elevation areas, more resources, and more diversity of habitats.

IUCN Status: All species at risk of extinction. See each species' risk level in Conservation Status.

CITES Appendix: I

Population in Wild: Approximately 20-25,000

Locomotion: Slow walk, but may move substantial distances. Float well, but swim with difficulty.

Activity Cycle: Most active during the day, but spend up to 16 hours resting. Spend active time foraging and walking between habitat areas. Immobile at night and exhibit sleep-like behaviors.

Diet: Plants and fruits—grasses, shrubs, Opuntia cactus. Can go months without food or water (generate water internally by metabolizing stored fat). Drink large amounts of water, if available.

Predators:
Introduced by humans: rats, pigs, goats, donkeys, fire ants (prey on eggs and young)
Native: Galápagos hawk

Reproduction & DevelopmentSpecies Highlights

Sexual Maturity: typically, about 20-25 years of age

Clutch Size:
Saddleback: 2-7 eggs
Domed: 20-25 or more eggs

Egg description: Spherical, white; 110-120 g (3.9-4.2 oz)

Incubation: Varies depending on species and seasonal temperatures; 80-175 days

Number of clutches: 1-4 per breeding season

Nesting season: June-December

Hatching season: December-April

Longevity: estimates vary
In the wild: over 100 years, possibly to 120 years or longer
In captivity: possibly up to 150 years

Feature Facts

  • The Galápagos Islands are named after these tortoises.
  • Able to go months without food or water. Seafarers in 18-20th centuries took advantage of this—stored live Giant Galápagos Tortoises (GGTs) in hulls of ships as source of fresh meat.
  • Overexploitation in the 1800s resulted in extinction of several species.
  • Exhibit long periods of inactivity when conditions are harsh.
  • Some individuals migrate with the seasons.
  • As they walk, carve paths through vegetation; shape plant communities through walking and eating.
  • Cool off in watery or muddy pools
  • Relationships with "cleaner birds"
  • Hatchlings remain in nest and wait to emerge at the same time
  • Ongoing programs to eradicate invasive species that are detrimental to GGT reproduction and survival; GGTs being reintroduced to some Galápagos Islands.

San Diego Zoo Global

  • The San Diego Zoo received its first tortoises in 1928; some of these original tortoises still live at the Zoo today.
  • First successful hatchings in 1958. For years, the San Diego Zoo had the only breeding colony in zoos, worldwide.
  • In 1977, as one of only 15 breeding individuals left, "Diego," a male Española Giant Tortoise, was sent back to the Galápagos to participate in a captive breeding program.
 

About This Fact Sheet

© 2017 San Diego Zoo Global

Abbreviations: GGT(s) is used as an abbreviation for Giant Galápagos Tortoise(s), throughout.

How to cite: Galapagos Tortoises (Chelonoidis spp.) Fact Sheet, 2017. c2017. San Diego (CA): San Diego Zoo Global; [accessed YYYY Mmm dd]. http://ielc.libguides.com/sdzg/factsheets/galapagostortoises.
(note: replace YYYY Mmm dd with date accessed, e.g., 2017 Jan 15)

Disclaimer: Although San Diego Zoo Global makes every attempt to provide accurate information, some of the facts provided may become outdated or replaced by new research findings. Questions and comments may be addressed to library@sandiegozoo.org.

 

Acknowledgments

Thank you to Kim Lovich, Curator of Herpetology & Ichthyology for San Diego Zoo Global, for providing expert content review of this fact sheet.

Many thanks to Linda Cayot, PhD, Galapagos Conservancy's Science Advisor, for providing key information on GGT taxonomy, population estimates, nesting biology, and morphometrics.

Thank you to Jonny Carlson, Reptile Keeper at the San Diego Zoo, for providing a wealth of information on GGT husbandry practices. We appreciate his knowledge of animal care and passion for reptiles.

Elizabeth A. Hunter, PhD, kindly responded to information requests regarding the biology and ecology of GGTs. Dr. Hunter conducted research on GGTs while earning her Master's degree. At the time of this writing, she is a postdoctoral researcher in ecology and conservation biology with the Department of Natural Resources and Environmental Science at the University of Nevada-Reno.

Thank you to Lisa Bissi, Photo Archive Librarian with San Diego Zoo Global, for sharing many of the historic photographs used in this fact sheet.

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