Natural History:
The Galapagos Giant Tortoise is the largest turtle in the world and stretches up to 1.22m in length and weigh as much as 385kg. This large size is due to living on an island rich in resources. Because of the lack of predators and the seemingly unlimited food supply there are no environmental stressors that would cause the tortoises to become smaller as they make the most if what their island home has to offer. By growing to such a large size, the Galapagos Giant Tortoise has filled the niche of large herbivore, a niche filled by large herbivorous mammals in other parts of the world.
The Galapagos Giant Tortoise is endemic to the Galapagos Archipelago although their ancestors likely originated from mainland South America. Often times animals that live close to the coast become lost at sea due to currents and undertows. These animals often land on islands where they colonize the new land and adapt over time. At one point, millions of years ago a relatively normal sized tortoise made its way to the Galapagos where it colonized and its population grew. From this common ancestor many Tortoise subspecies sprouted to suit the different habitats on each island. This occurred as mutations arise normally in a population and if this mutation proved to be advantageous than it would be better able to reproduce and share that mutation with its offspring. Over time that mutation becomes more prevalent within the population and after many small mutations the isolated population of tortoises has adapted a different physiology than tortoises on neighboring islands. Some Tortoises adapted to a desert environment evolved a saddle like structure on the front of the shell and a long neck, the structure on the shell allowed the long neck to stretch upwards to eat tall cacti. Tortoises on more tropical islands such as the Santa Cruz subspecies instead has a shorter neck and no growth on its shell as all the food they need is accessible on the forest floor and a long neck is not needed to reach it. This process of evolving to a habitat by advantageous mutations is known as evolution by natural selection. This theory was described by Charles Darwin after he had visited the Galapagos Islands. On the islands he was fascinated by the difference in tortoise shell shapes and the differing beaks of different birds as they varied on different islands which had different environments.
The Galapagos Islands were at one time a popular stop for sailors to stock up on supplies. before crossing the Atlantic Ocean. When they stopped on the Galapagos they would often take with them Galapagos Giant Tortoises which they would as food. The Tortoises are said to have large amounts of meat and were able to feed the entire crew. They were also able to keep them for long periods of time with little food and water making them idea for sea faring. This practice has unfortunately decimated Giant Tortoise populations however in recent years their population has bounced back due to new conservation methods to protect entire islands, eliminating invasive species and through captive breeding programs. Some species however have gone extinct with the latest being the Pinta Island Giant Tortoise Chelonoidis abingdonii† which went extinct in 2012 when the last known pure form, nicknamed "Lonesome George" passed away.
The Galapagos Giant Tortoise is the largest turtle in the world and stretches up to 1.22m in length and weigh as much as 385kg. This large size is due to living on an island rich in resources. Because of the lack of predators and the seemingly unlimited food supply there are no environmental stressors that would cause the tortoises to become smaller as they make the most if what their island home has to offer. By growing to such a large size, the Galapagos Giant Tortoise has filled the niche of large herbivore, a niche filled by large herbivorous mammals in other parts of the world.
The Galapagos Giant Tortoise is endemic to the Galapagos Archipelago although their ancestors likely originated from mainland South America. Often times animals that live close to the coast become lost at sea due to currents and undertows. These animals often land on islands where they colonize the new land and adapt over time. At one point, millions of years ago a relatively normal sized tortoise made its way to the Galapagos where it colonized and its population grew. From this common ancestor many Tortoise subspecies sprouted to suit the different habitats on each island. This occurred as mutations arise normally in a population and if this mutation proved to be advantageous than it would be better able to reproduce and share that mutation with its offspring. Over time that mutation becomes more prevalent within the population and after many small mutations the isolated population of tortoises has adapted a different physiology than tortoises on neighboring islands. Some Tortoises adapted to a desert environment evolved a saddle like structure on the front of the shell and a long neck, the structure on the shell allowed the long neck to stretch upwards to eat tall cacti. Tortoises on more tropical islands such as the Santa Cruz subspecies instead has a shorter neck and no growth on its shell as all the food they need is accessible on the forest floor and a long neck is not needed to reach it. This process of evolving to a habitat by advantageous mutations is known as evolution by natural selection. This theory was described by Charles Darwin after he had visited the Galapagos Islands. On the islands he was fascinated by the difference in tortoise shell shapes and the differing beaks of different birds as they varied on different islands which had different environments.
The Galapagos Islands were at one time a popular stop for sailors to stock up on supplies. before crossing the Atlantic Ocean. When they stopped on the Galapagos they would often take with them Galapagos Giant Tortoises which they would as food. The Tortoises are said to have large amounts of meat and were able to feed the entire crew. They were also able to keep them for long periods of time with little food and water making them idea for sea faring. This practice has unfortunately decimated Giant Tortoise populations however in recent years their population has bounced back due to new conservation methods to protect entire islands, eliminating invasive species and through captive breeding programs. Some species however have gone extinct with the latest being the Pinta Island Giant Tortoise Chelonoidis abingdonii† which went extinct in 2012 when the last known pure form, nicknamed "Lonesome George" passed away.