- Common name: Galapagos tortoise, giant Galapagos tortoise. The word tortoise is usually used for terrestrial turtles in the family Testudinidae.
- Scientific name: Chelonoidis nigra
- Galapagos tortoises are the only surviving lineage of giant turtles in the world that show two different types of shell shapes.
- There are two remaining families of giant tortoises in the world the Galapagos tortoise and the Aldabra Atoll tortoise of Seychelles in the Indian Ocean.
- This reptile is the largest living species of tortoise.
- They have a large brown bony carapace with large variation in size and shape in all subspecies.
- The main types are:
- Saddle-shaped, flat carapace with long neck. Smaller in size. Males can be up to 3 times heavier than females.
- Dome carapace, shorter neck and limbs. Larger in size. Males and females are about the same size.
- Intermediate between the saddle and dome shape.
- Carapace grows by increasing in diameter of each bony plate but it is not useful in determining age as the outer edges wear over time.
- A tortoise can hide its head and limbs into its carapace for protection.
- Their legs are short and stumpy and are covered with hard scales.
Distribution and Habitat
- The Galapagos tortoise inhabits the Galapagos Archipelago Islands off the coast of Ecuador.
- Larger tortoises with domed shaped carapace and short necks inhabit islands where volcanic highlands are high in humidity. During the rainy season they migrate to lowlands.
- Smaller tortoises with saddle shape carapace and long necks live on lowland islands with low humidity.
Length and Weight
- Males weigh from 600 to 700 lbs or 272 to 317 kg.
- Females weigh from 300 to 400 lbs or 136 to 181 kg.
- They can reach lengths up to 6 ft or 1.8 m.
- They spend most of their waken time foraging.
- Galapagos tortoises sleep up to 16 hours a day.
- Tortoises move slowly at speeds as low as 0.2 mph or 0.3 km/h.
- Males display aggressive behavior. Usually the smaller saddleback dominates dome carapace tortoises.
- They can flip themselves if turned upside down on their backs.
- Not very good swimmers but can float on water.
- Their digestion is influenced by atmosphere temperature. The higher the temperature the faster the digestion.
- On larger and humid islands Galapagos tortoises migrate from highlands to lowlands during rainy season.
- Tortoises are ectotherm. They are cold blooded animals so they need to regulate their body temperature by basking in the sun or cooling down in water.
- They feed on cactus, grass, fruits and berries.
- They can survive without food or water for at least 6 months.
- Reproductive maturity is reached at age 20 to 25 when raised in captivity. In the wild it is possible that they reach maturity at around 40 years old.
- Males compete against each other for females.
- Breeding peaks between February and June during the rainy season.
- They mate at humid higher elevations and move to lower and drier areas for nesting.
- Females lay from 1 to 4 clutches per season during the dry season between July and November.
- Clutch size ranges from 8 to 17 depending on the subspecies. Approximately 78% of eggs hatch.
- Incubation takes from 3 to 8 months depending on the temperature.
- Eggs hatch late December to April.
- It is estimated that Galapagos tortoises live up to 150 years.
- Habitat restriction due to human settlements.
- Introduced feral dogs and cats into the islands.
- Poaching for its meat.
- Hatchings and young tortoises can die due environmental conditions such as excessive heat and flooding.
- Late reproductive maturity and slow growth rate make Galapagos turtles vulnerable to extinction.
- The Galapagos tortoise is listed as vulnerable in the IUCN Red List of Threatened Species.
- Listed in Appendix I of CITES.
- They are protected by the Galapagos National Park Service.
- On his second voyage Charles Darwin observed differences in the tortoises carapace and their habitat contributing to the development of his theory of evolution.
- Five of the fifteen tortoise subspecies have become extinct because of human interference.
- Tortoise highways are referred to a path used for many generations by dome carapace tortoises to migrate between highlands to lowlands during the rainy season.
- The longest living Galapagos turtle, Harriet, lived to 170 years old. She was kept in Australia Zoo and died in 2006.
- The Galapagos Islands were named after the giant tortoises. In old Spanish galapago meant saddle as in the shape of their carapace.