The Galapagos tortoise is the largest tortoise on Earth. Some Galapagos tortoises live to be the oldest creatures on Earth, more than 100 years old. Galapagos tortoises are found only on the islands of the Galapagos Archipelago in the eastern Pacific Ocean, of the coast of equatorial Ecuador.
Galapagos tortoises grow up to 4 feet (1.2 m) long and weigh as much as 660 pounds (300 kg). The Galapagos tortoise has a huge shell (called a carapace), massive legs, and a long neck. The Galapagos tortoise is toothless but has strong jaws and is well adapted to feeding on vegetation.
There are two types of Galapagos tortoise. The first has a big, round “domed” shell, and the second has a slightly smaller “saddleback” shell–that is a saddle-like arch in the shell just above the tortoise’s neck. This adaptation is thought to be the result of where and how tortoises feed. Some live on islands that are grassier with vegetation low to the ground; others live on more arid islands where vegetation such as prickly pear cactus is higher up off the ground; these tortoises can feed only by craning their heads and necks up to nibble the tall-growing cacti so their shell has adapted to this need. (Charles Darwin cited these shell differences to support his theory of natural selection.)
Galapagos tortoises spend most of their time grazing in small herds and basking in pools. Because much of the year is dry on the Galapagos islands, the tortoises have adapted and are able to go for long periods without food or water. When the dry time of the year comes, some Galapagos tortoises migrate from the dry lowlands to the more humid highlands. It takes them three weeks to migrate about 4 miles (6 km).
The large size of the Galapagos tortoises’ shell allows them to store food energy and water for long periods. Their unhurried lifestyle and slow metabolism allow them to go a whole year without eating vegetation or drinking water if necessary.
Galapagos tortoises can live for more than 100 years. One female Galapagos tortoise is known to have lived 170 years. The scientific name of the Galapagos tortoise is Chelnoidis elephantopus.