The giant tortoises of Galapagos are among the most famous of the unique fauna of the Islands. I am extremely fascinated of these giant pre-historical animals.
The Galapagos Islands were named for their giant tortoises; the old Spanish word “galapago” meant saddle, a term early explorers used for the tortoises due to the shape of their shells. While giant tortoises once thrived on most of the continents of the world, the Galapagos tortoises now represent one of the remaining two groups of giant tortoises in the entire world — the other group living on Aldabra Atoll in the Indian Ocean. Although there is a great amount of variation in size and shape among Galapagos tortoises, two main morphological forms exist – the domed carapace (left picture) and the saddle-backed carapace (right picture). Source: https://www.galapagos.org/about_galapagos/about-galapagos/biodiversity/tortoises/
The domed tortoises tend to be much larger in size and do not have the upward thrust to the front of their carapace. They live on the larger, higher islands with humid highlands where forage is generally abundant and easily available. So we rented two bicycles and headed for the highlands on Santa Cruz.
It was pretty much up hill all the way to the small town Santa Rosa, where we turned of the main road. As soon as we turned on to the dirt road leading to Ranch El Chato the giant tortoises were everywhere.
It was great to be on the bicycles, because we could just stop every time we saw a tortoise. A lot of taxi’s do a 40 minute trip from Puerto Ayora, but they only stop at the ranch and the nearby lave tunnel. We spend 5-6 hours, and took a lot of pictures.
You can get really close to the tortoises, but always respect the animals. In the right picture you see one of the biggest tortoises that we saw on our way – once again it was just amazing! These tortoises can weigh as much as 417 kg (919 lb) and can grow to be 1.3 m (4 ft 3 in) long. Giant tortoises are among the world’s longest-living animals, with an average lifespan of 100 years or more. Some giant tortoises have lived a life in a zoo, and a few tortoises have lived for about 176 and 255 years.
Saddle-backed shells evolved on the arid islands in response to the lack of available food during drought. The front of the carapace angles upward, allowing the tortoise to extend its head higher to reach the higher vegetation, such as cactus pads. All our pictures of the saddle-back tortoises are from the Darwin Research Center in Puerto Ayora.
Galapagos tortoises are herbivorous, feeding primarily on cactus pads, grasses, and native fruit
Depending on when you visit the Darwin Center the tortoises will be active or inactive. We were lucky to visit around lunch time, and the tortoises had been feed (just ask when the tortoises will be feed next time, and plan your visit according to the feeding). They were really active, walking around and eating. If you visit in the afternoon the tortoises are more likely just to lay on the ground. Also the tortoises in the wild were more active.
A few close ups – notice the deferens between the shells
With the establishment of the Galapagos National Park and the Charles Darwin Foundation in 1959, a systematic review of the status of the tortoise populations began. Only 11 of the 14 originally named populations remained and most of these were endangered if not already on the brink of extinction. The giant tortoises can no longer reproduce in the nature. To avoid total extinction there has been established three breading centers, one on each island: Santa Cruz, Isabela and San Christobal.
In the wild the tortoises seek out a dry places with the right temperature and enough earth to dig a nest. After digging the nest the tortoises will lay 6-14 eggs (this a lot less compared to a sea turtle, that can lay about 100 eggs in one nest). When the nest hatch, the newborns have to scrape away the hardened earth of the nest. It take about 30 days before the newborns reach the surface, during this time they don’t have anything to eat or drink. They survive thanks to a food reserve inside their bodies. When the newborns leave the nest, they have to survive on their own. At present, no tortoise born in the wild manage to survive, therefore the breeding centers are necessary for the tortoises to survive.
These are the threats that makes in impossible for the tortoises to reproduce in the wild
Maybe you have heard about “Lonesome George”. He was a male Pinta Island tortoise (Chelonoidis abingdonii) and the last known individual of the species and died June 24, 2012 his estimated ages was 102 years. George was first seen on the island of pinta on 1 November 1971. The island’s vegetation had been devastated by introduced feral goats, and the indigenous C. abingdonii population had been reduced to a single individual. George was then penned with two females of a different subspecies. Although eggs were produced, none hatched. Unfortunately, no other Pinta tortoises were found. The Pinta tortoise was pronounced functionally extinct as George was in captivity (Source: https://en.wikipedia.org/wiki/Lonesome_George). Today the stuffed Lonesome George are displayed at the Charles Darwin Research Center.
That was all I had about the giant tortoises on Galapagos – love them and hope that they will survive due to the breeding program