There are 13 living species of Galapagos tortoises, which are also commonly known as giant tortoises. These prehistoric creatures are said to have first arrived in the archipelago two to three million years ago, migrating from the South American coast and drifting 600 miles to the shores of the Galapagos. These reptiles are endemic to the Galapagos Islands, meaning it is the only place in the world you will get the chance to see them in the wild.
Giant tortoises are one of the longest living land vertebrates, averaging more than a hundred years. The oldest on record lived to be 175! You may be “shocked” to hear that they are also the world’s largest tortoises, with some specimens exceeding five feet in length and reaching more than 500 pounds. That’s the same weight as almost four washing machines!
Giant tortoises have thick legs and small air chambers inside their shells that help hold up their massive bodies. There are two main types: domed tortoises which live in the cooler regions of the archipelago, and saddle-backed tortoises, which live in dry, coastal environments. Saddleback shells have a flared front opening that allows the animals to extend their necks to reach tall cacti. Dominance amongst tortoises is decided by who can stretch their neck and head the highest. They will stand facing each other and compare heights to decide who gets dibs on the best food, resting spots and basking areas.
Galapagos tortoises lead an uncomplicated life, grazing on grass, leaves, and cactus, basking in the sun and resting for nearly 16 hours per day. They can store large amounts of water and have a very slow metabolism. This allows them to survive up to a year without eating or drinking! They play a key role in shaping the ecosystem of the Galapagos by dispersing plants seeds in their dung. They also trample vegetation and create permanent trails and dig holes for their nests. This has earned them the title, ‘the gardeners’ of the Galapagos. Although their shells may look tough, they do have a sensitive side. The surface of the shell or carapace is full of blood vessels and nerves, making it very sensitive to touch. It’s also made of a honeycomb-like structure and is relatively light, allowing the tortoise to be able to walk around. The bottom of the shell, or plastron, is more solid and protects the bottom of the tortoise from the rough terrain below. Tortoises can’t walk out of their shells like you see in cartoons. The ribs and backbone of the tortoise are fused to the bones in its shell.
Giant tortoises reach maturity at about 20 or 25 years old. They typically breed during the hot season, which occurs from January to May. Mating can take several hours, after which the female migrates to an area with dry, sandy ground. There, she digs a hole in which she lays two to 16 eggs. The eggs hatch after around 130 days but scientists are still at a loss as to what they get up to next. It’s a mystery that’s referred to as ‘the lost years’ by conservationists. The tortoises don’t turn up again until they are around five years old and 50cm long. Which is just big enough that the tortoise’s only native predator – the Galápagos hawk (above) – can’t carry them off!