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Researched and devised by Dr. Oliphant Jackson, the Jackson ratio is a method of determining whether a member of the tortoise species Testudo graeca or Testudo hermanni is maintaining its optimum bodyweight, which is necessary for a successful hibernation. The Jackson Ratio is calculated by taking the weight of the tortoise in grams and dividing it by the cube of the length of the tortoise's carapace in centimeters. This is essentially a value of the density of the tortoise in g/cm^3. The optimal value for this ratio is 0.21 with a range of 0.18 - 0.22 being acceptable for hibernation. Values significantly less than this indicate an underweight tortoise and larger values are indicative of overweight tortoises. The Jackson Ratio is expressed as a graph of minimum and optimum weights for a given carapace length. This exhibits the same principle without the maths.
Tortoises are reptile species of the family Testudinidae of the order Testudines. They are particularly distinguished from other turtles by being land-dwelling, while many other turtle species are at least partly aquatic. However, like other turtles, tortoises have a shell to protect from predation and other threats. The shell in tortoises is generally hard, and like other members of the suborder Cryptodira, they retract their necks and heads directly backwards into the shell to protect them.
Hibernation is a state of inactivity and metabolic depression in endotherms. Hibernation refers to a season of heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most commonly occurs during winter months.
A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.
The Tortoise Protection Group (TPG) is a British non-profit organisation founded in January 2007 with the aim of stopping the importation of tortoises into the UK for the commercial pet trade, and to promote high standards of husbandry in tortoise keeping. The mission of the Tortoise Protection Group is to help ensure the survival of tortoises in the wild and to promote high standards of husbandry for tortoise keepers in the UK. Over the last year, it has been working closely with members of Parliament and various charities to bring about a change in legislation, with a petition enlisting thousands of signatures.
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The Geoemydidae are one of the largest and most diverse families in the order Testudines (turtles), with about 70 species. The family includes the Eurasian pond and river turtles and Neotropical wood turtles.
The Bottleneck traveling salesman problem is a problem in discrete or combinatorial optimization. The problem is to find the Hamiltonian cycle in a weighted graph which minimizes the weight of the most weighty edge of the cycle. It was first formulated by Gilmore & Gomory (1964) with some additional constraints, and in its full generality by Garfinkel & Gilbert (1978).
The common snapping turtle is a large freshwater turtle of the family Chelydridae. Its natural range extends from southeastern Canada, southwest to the edge of the Rocky Mountains, as far east as Nova Scotia and Florida. The three species of Chelydra and the larger alligator snapping turtles are the only extant chelydrids, a family now restricted to the Americas. The common snapping turtle, as its name implies, is the most widespread.
The marginated tortoise is a species of tortoise in the family Testudinidae. The species is endemic to Greece, Italy, and the Balkans in Southern Europe. It is the largest European tortoise. The marginated tortoise is herbivorous, and hibernates for the winter.
The Greek tortoise, also known commonly as the spur-thighed tortoise, is a species of tortoise in the family Testudinidae. Testudo graeca is one of five species of Mediterranean tortoises. The other four species are Hermann's tortoise, the Egyptian tortoise, the marginated tortoise, and the Russian tortoise. The Greek tortoise is a very long-lived animal, achieving a lifespan of upwards of 125 years, with some unverified reports of up to 200 years.
Hermann's tortoise is a species in the genus Testudo. Two subspecies are known: the western Hermann's tortoise and the eastern Hermann's tortoise. Sometimes mentioned as a subspecies, T. h. peleponnesica is not yet confirmed to be genetically different from T. h. boettgeri.
The Aldabra giant tortoise, from the islands of the Aldabra Atoll in the Seychelles, is one of the largest tortoises in the world. Historically, giant tortoises were on many of the western Indian Ocean islands, as well as Madagascar, and the fossil record indicates giant tortoises once occurred on every continent and many islands with the exception of Australia and Antarctica. Many of the Indian Ocean species were thought to be driven to extinction by over-exploitation by European sailors, and they were all seemingly extinct by 1840 with the exception of the Aldabran giant tortoise on the island atoll of Aldabra. Although some remnant individuals of A. g. hololissa and A. g. arnoldi may remain in captivity, in recent times, these have all been reduced as subspecies of A. g. gigantea.
The Arakan forest turtle is a rare turtle species which lives only in the Arakan Hills of western Myanmar and the bordering Chittagong Hill Tracts of Bangladesh. The Arakan forest turtle is a semiterrestrial turtle, meaning it can survive in aquatic as well as terrestrial habitats, but as adults, they prefer living in terrestrial habitats.
The Giant Asian pond turtle inhabits rivers, streams, marshes, and rice paddies from estuarine lowlands to moderate altitudes throughout Cambodia and Vietnam and in parts of Laos, Malaysia, Myanmar and Thailand.
The leopard tortoise is a large and attractively marked tortoise found in the savannas of eastern and southern Africa, from Sudan to the southern Cape. It is the only member of the genus Stigmochelys, although in the past it was commonly placed in Geochelone. This tortoise is a grazing species that favors semi-arid, thorny to grassland habitats. In both very hot and very cold weather they may dwell in abandoned fox, jackal, or aardvark holes. Leopard tortoises do not dig other than to make nests in which to lay eggs. Given its propensity for grassland habitats, it grazes extensively upon mixed grasses. It also favors succulents and thistles.
Chersobius signatus is the world's smallest species of tortoise. The species is commonly known as the speckled tortoise and also known locally as the speckled padloper and internationally as the speckled Cape tortoise. A member of the genus Chersobius, it is endemic to South Africa.
The elongated tortoise is a species of tortoise found in Southeast Asia and parts of the Indian Subcontinent, particularly Northeast India.
The Asian forest tortoise, also known commonly as the Asian brown tortoise, is a species of tortoise in the family Testudinidae. The species is endemic to Southeast Asia. It is believed to be among the most primitive of living tortoises, based on molecular and morphological studies.
The Mediterranean tortoises (Testudo) are a genus of tortoises found in North Africa, western Asia, and Europe. Several species are under threat in the wild, mainly from habitat destruction.
The radiated tortoise is a species in the family Testudinidae. Although this species is native to and most abundant in southern Madagascar, it can also be found in the rest of this island, and has been introduced to the islands of Réunion and Mauritius. It is a very long-lived species, with recorded lifespans of at least 188 years. These tortoises are classified as critically endangered by the IUCN, mainly because of the destruction of their habitat and because of poaching.
Kleinmann's tortoise, often called the Egyptian tortoise and occasionally Leith's tortoise, is a critically endangered species of neck-hiding tortoise in the family Testudinidae. The species is endemic to Egypt and Libya. The species was once more widespread, but its numbers are now dwindling. The species is nearly extinct in Egypt, and complete extinction in the wild is a looming threat unless more actions are taken to protect this species.
The Argentine snake-necked turtle, also known commonly as the South American snake-necked turtle is a species of turtle in the family Chelidae. The species is known for the long neck to which its common names refer. Despite appearances, the Argentine snake-necked turtle is probably more closely related to the mata mata than to the Australian snake-necked turtles in the genus Chelodina. H. tectifera is found in northern Argentina, Uruguay, Paraguay, and southern Brazil. Not much is known about it, as it has not been extensively researched. It is a popular pet in the exotic pet trade.
The Armenian tortoise or Araxes tortoise is a subspecies of the common tortoise.
The angonoka tortoise is a critically endangered species of tortoise endemic to Madagascar. It is also known as the angonoka, ploughshare tortoise, Madagascar tortoise, or Madagascar angulated tortoise.