The tortoises in the Galapagos Islands all had various shaped shells, indicating that they were different species of the same tortoise group. Tortoises on Pinta Island, for example, had intermediate shells, while those on Hood Island had saddle-backed shells and those on Isabela Island had dome-shaped shells. This shows that the shape of their shell is not always a good guide to determine how closely related two tortoises are. In this case, the tortoises' skin patterns helped scientists to identify them as being members of the same species.
Tortoises live in every country in the world except Antarctica. They are found on all major continents except Australia and Antarctica. They have even been discovered in Greenland! But they are most common in tropical regions with warm temperatures year round. They like it when the temperature is between 50 degrees Fahrenheit and 90 degrees Fahrenheit all year long.
Tortoises get their name because they look like turtles from the side but when you turn them over they are not actually covered with skin like true turtles. Tortoises are herbivores and eat plants all day long. They use their tongues to sweep through the ground looking for food. If they find something tasty, they will grab it with their mouths and carry it back to their nests to feed their babies.
Tortoises are important to humans because they provide food and oil. Their meat is eaten fresh or dried and stored for later consumption or traded.
Tortoises of the Galapagos The shells of Galapagos tortoises varies based on whatever island they live on. Tortoises with saddle-shaped shells have the ability to reach up and consume plant leaves over their heads. These two tortoises reside on distinct islands with varied habitats and food supplies. However, they share similar shapes because of inheritance from a common ancestor.
Saddle-shaped shells are useful for reaching high plants. A tortoise can extend its neck so far that it reaches beyond the limits of its body, allowing it to eat fruit from high in a tree. This shape also allows a tortoise to fit inside its shell when it is dry, which helps protect it from heat stress and rainwater runoff during storms. Although this feature is beneficial, it can also be detrimental to tortoises that lack environmental knowledge. They believe the only way to get water is by pulling it down from the sky through their mouths, which can lead to drowning if there's no release valve.
In conclusion, tortoises with saddle-shaped shells can reach high up in trees where other tortoises cannot. This advantage allows them to eat different foods than those available to smaller tortoises. Additionally, their extended necks allow them to drink when their shells become full of water. Despite these benefits, tortoises with this type of shell can also be prone to flooding due to their inability to regulate their own temperature.
The Galapagos tortoises on each island are distinguished by minor characteristics. Santa Cruz (previously Indefatigable Island) tortoises have "dome-shaped" shells. These shelled animals live on islands where the majority of the flora is near to the ground, eliminating the need for them to elevate their heads to feed. Charles Darwin observed that these tortoises had large ears like those of a camel and used this as evidence of natural selection in action.
Geoffrey Benninghaus notes that there are three major differences between the tortoises of Santa Cruz and those of San Cristobal (which was then known as Ancud Island): 1 The shell of the former is flatter; 2 The ribs on which they lie are more widely spaced; 3 Their necks are shorter. This shows that even within one species, individuals tend to be either big or small, depending on how much food they find available. As well as eating plants, these turtles also eat small animals such as lizards and worms, so are capable of surviving for long periods without eating if the need arises.
These observations led Darwin to propose that each population of tortoise represented a unique evolutionary stage in which larger individuals would be better able to survive due to their greater strength and ability to eat larger meals. He called this process "natural selection".
Tortoises from various islands may be distinguished by the form of their shells, which appear to have developed into two distinct varieties with minor differences. Tortoises with a dome-shaped shell and a short neck live on lushly vegetated islands such as Santa Cruz Island. Those with a flat shell and long neck inhabit more arid islands such as those in the Galapagos Islands.
The shape of the shell is determined by the position in which the embryo develops when the female turtle swallows it in order to protect it from predators. If the egg rolls over onto its side, then the resulting shell shape will be dome-like; if face up, then the shell will be flat.
Also, turtles from different islands tend to be distinctively colored. For example, the chelonians (turtles) found in the Caribbean are generally green or brown while those in Central America are usually yellow or red. This difference in color is probably due to evolutionary pressure putting different traits into animals living on different islands. For example, since plants on small islands can't move away from pests, they develop defenses that aren't available on larger islands where predators keep pest numbers down.
Finally, turtles from various islands may have different abilities for moving about. For example, sea turtles depend on being able to swim to find food and water, so they would not be expected to travel far unless forced to do so.