All About the Galapagos Islands Tortoises21 Nov 2016, Posted by Galapagos Islands Blog in
The Galapagos tortoises are native to seven of the Galapagos Islands, a volcanic archipelago that is about 620 miles west of the mainland of Ecuador. The islands were named by Spanish explorers in the late 16th century. Because of the giant tortoises found there, they were named Insulae de los Galapagos, which means Islands of the Tortoises in Spanish. Learn about the Galapagos Islands tortoises, the most impressive creatures in the archipelago.
History of Galapagos Tortoises
The Galapagos tortoise is thought to be an ancestral relation to tortoises from mainland South America. There is DNA evidence that the closest living relative to the Galapagos tortoise is the Chaco tortoise that is native to Argentina and Paraguay. It is believed that the tortoises floated from the mainland to the volcanic islands over 5 million years ago. They were able to survive the 620-mile ocean journey because they are buoyant, can extend their necks up for air, and can live for months without fresh water or food.
Over time, the tortoises evolved to meet the needs of their new environment. They populated the other Galapagos Islands by traveling “stepping-stone style” from one to another.
Species of Galapagos Tortoises
Scientists have identified 15 different sub-species of the Galapagos tortoise, although there are only 10 species alive at this time. An 11th sub-species, now extinct, had one member nicknamed “Lonesome George” until he passed on in 2012. Of the 10 remaining species, five inhabit the largest island, Isabella, while there are six subspecies that are on separate, smaller islands. Many of the living subspecies are currently endangered or threatened species, but conservationists are working hard to increase their numbers.
Why are Galapagos Tortoises Endangered?
It is believed that when these giant tortoises were discovered in the 1600s, there were over 250,000 of them. While the lowest numbers were seen in the 1970s at about 3,000, there are currently approximately 20,000 Galapagos tortoises living in the islands. Conservation efforts have had great success with breeding programs to increase the populations.
It is believed that many of the tortoises were hunted by humans for meat and oil. Others may have died off when non-native animals such as pigs, goats and rats were introduced to the islands. In the past 50 years, many subspecies were bred in captivity and released to their native habitats to repopulate those areas.
Learn about the Galapagos Islands Tortoises Size
Galapagos tortoises are quite large, and even their legs and feet are large and thick, resembling that of an elephant. Another important fact to note is that their front feet have five claws while those on the back have only four. Despite their size, the tortoises can pull all four of their feet and their heads inside of their shells for protection.
The actual measurements and weights of these tortoises can vary depending on individuals and subspecies. Some of the smaller tortoises live on the island of Pinzon. The largest of these smaller tortoises weighs in at about 168 pounds with a shell size of about 2 feet. Many of the tortoises on the other islands, however, are much larger. The largest recorded Galapagos tortoise weighed in at approximately 880 pounds, and its shell measured over 6 feet across.
The Shells of the Galapagos Tortoises
The shells, scientifically known as carapaces, are fused with the ribs and are a protective part of the tortoise’s make-up. The shells are dull brown in color and have characteristic patterns that remain the same throughout the tortoise’s life.
Two different shell types are common, depending mostly on where the tortoise lives. Some tortoises have saddleback shells, which are longer than they are wide and arch upwards at the front. When a tortoise brings its front legs and head inside of a saddleback shell, there is a gap, which denotes to scientists that these tortoises have few, if any, natural predators. Other tortoises have a domed shell that is totally concave in shape.
About the Galapagos Islands Tortoises Behaviors and Eating Habits
An important fact about the Galapagos Islands tortoises is that as cold-blooded reptiles, they like to warm up each morning before heading out in search of food. They will often lie in the sun for several hours. In the evening, when they are ready to sleep, they often lie in a shallow pit or in the close quarters of rock caves.
Giant tortoises are herbivores, eating many plants and fruits that are native to the islands they live on and spending a good part of their days foraging for food. As for water, they get most of this from the dew in the grasses and the moisture in the vegetation they eat. They can go for six months to a year without any food or water, living on the fat stored in their bodies.
Life Cycle of Galapagos Tortoises
Mating rituals require males to dominate over other males for the right to mate with a female. The actual process of domination and mating can be somewhat aggressive. Typically, tortoises mate from February to June, but it can occur at any time.
Several months later, the females search for a dry place to build a nest and lay their eggs. They can lay up to 16 eggs per nest. Temperature will determine the gender of the hatchlings. Eggs near the surface, incubated at a slightly warmer temperature, will yield mostly females, while the slightly cooler-incubated eggs, will take longer and will produce mostly males. After digging their way out of the sealed nest, the hatchlings emerge four to eight months later, weighing less than a pound. They stay in the warmer, dryer climates for the first 10-15 years of life, not reaching sexual maturity until possibly 40 years old. As hatchlings, they face much adversity, from encounters with the Galapagos hawks to the possibility of falling into cracked earth. However, those that survive live to be over 100 years old in the wild.