Land Tortoise Stock Picture I4923417 at FeaturePics
In the 17th century, performed an experiment that involved removing the brain of a land tortoise, which then proceeded to live six months. Freshwater tortoises, when subjected to the same experiment, continued similarly, but did not live so long. Redi also cut the head off a tortoise entirely, and it lived for 23 days.
An estimated 200,000 animals were taken before the 20th century. The relatively immobile and defenceless tortoises were collected and stored live on board ships, where they could survive for at least a year without food or water (some anecdotal reports suggest individuals surviving two years), providing valuable fresh meat, while their diluted urine and the water stored in their neck bags could be used as drinking water. The 17th-century British pirate, explorer, and naturalist wrote, "They are so extraordinarily large and fat, and so sweet, that no pullet eats more pleasantly," while Captain of the British Navy wrote of "the land tortoise which in whatever way it was dressed, was considered by all of us as the most delicious food we had ever tasted." US Navy captain declared, "after once tasting the Galapagos tortoises, every other animal food fell off greatly in our estimation ... The meat of this animal is the easiest of digestion, and a quantity of it, exceeding that of any other food, can be eaten without experiencing the slightest of inconvenience." Darwin was less enthusiastic about the meat, writing "the breast-plate roasted (as the Gauchos do "carne con cuero"), with the flesh on it, is very good; and the young tortoises make excellent soup; but otherwise the meat to my taste is indifferent."
The uses "turtle" to describe all species of the order Testudines, regardless of whether they are land-dwelling or sea-dwelling, and uses "tortoise" as a more specific term for slow-moving terrestrial species. General American usage agrees; turtle is often a general term (although some restrict it to aquatic turtles); tortoise is used only in reference to terrestrial turtles or, more narrowly, only those members of , the family of modern land tortoises; and terrapin may refer to turtles that are small and live in fresh and brackish water, in particular the (). In America, for example, the members of the genus dwell on land, yet are referred to as rather than tortoises.Most land-based tortoises are , feeding on grasses, weeds, leafy greens, flowers, and some fruits, although some omnivorous species are in this family. Pet tortoises typically require diets based on wild grasses, weeds, leafy greens and certain flowers. Certain species consume or and carrion in their normal habitats. Too much protein is detrimental in herbivorous species, and has been associated with shell deformities and other medical problems. As different tortoise species vary greatly in their nutritional requirements, it is essential to thoroughly research the dietary needs of individual tortoises.Australian usage is different from both American and British usage. Land tortoises are not native to Australia, yet traditionally freshwater turtles have been called "tortoises" in Australia. Some Australian experts disapprove of this usage—believing that the term tortoises is "better confined to purely terrestrial animals with very different habits and needs, none of which are found in this country"—and promote the use of the term "freshwater turtle" to describe Australia's primarily aquatic members of the order Testudines because it avoids misleading use of the word "tortoise" and also is a useful distinction from marine turtles.The five populations living on the largest island, Isabela, are the ones that are the subject of the most debate as to whether they are true species or just distinct populations or subspecies. It is widely accepted that the population living on the northernmost volcano, Volcan Wolf, is genetically independent from the four populations to the south and is therefore a separate species. It is thought to be derived from a different colonization event than the others. A colonization from the island of Santiago apparently gave rise to the Volcan Wolf species () while the four southern populations are believed to be descended from a second colonization from the more southerly island of Santa Cruz. Tortoises from Santa Cruz are thought to have first colonized the Sierra Negra volcano, which was the first of the island's volcanoes to form. The tortoises then spread north to each newly created volcano, resulting in the populations living on Volcan Alcedo and then Volcan Darwin. Recent genetic evidence shows that these two populations are genetically distinct from each other and from the population living on Sierra Negra () and therefore form the species (Alcedo) and (Darwin). The fifth population living on the southernmost volcano () is thought to have split off from the Sierra Negra population more recently and is therefore not as genetically different as the other two. Isabela is the most recently formed island tortoises inhabit, so its populations have had less time to evolve independently than populations on other islands, but according to some researchers, they are all genetically different and should each be considered as separate species.