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?Tortoises
A Galápagos Giant Tortoise
A Galápagos Giant Tortoise
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Testudines
Suborder: Cryptodira
Superfamily: Testudinoidea
Family: Testudinidae
Genera

Chersina
Cylindraspis (extinct)
Dipsochelys
Geochelone
Gopherus
Homopus
Indotestudo
Kinixys
Malacochersus
Manouria
Psammobates
Pyxis
Stylemys (extinct)
Testudo

Main article: Turtles

Tortoises or land turtles are land-dwelling reptiles of the family of Testudinidae, order Testudines. Like their marine cousins, the sea turtles, tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The tortoise has both an endoskeleton and an exoskeleton. Tortoises can vary in size from a few centimeters to two meters. Tortoises tend to be diurnal animals with tendencies to be crepuscular depending on the ambient temperatures. They are generally reclusive animals.

Turtles, tortoises and terrapinsEdit

Differences between turtles, tortoises and terrapins

BiologyEdit

BirthEdit

Female tortoises dig nesting burrows in which they lay from one to thirty eggs.[1] Egg laying typically occurs at night, after which the mother tortoise covers her clutch with sand, soil, and organic material. The eggs are left unattended, and depending on the species, take from 60 to 120 days to incubate.[2] The size of the egg depends on the size of the mother and can be estimated by examining the width of the cloacal opening between the carapice and plastron. The plastron of a female tortoise often has a noticeable V-shaped notch below the tail to facilitate passing the eggs. Upon completion of the incubation period, a fully-formed hatchling uses an egg tooth to break out of its shell. It digs to the surface of the nest and begins a life of survival on its own. Hatchlings are born with an embryonic egg sac which serves as a source of nutrition for the first 3 to 7 days until they have the strength and mobility to find food. Juvenile tortoises often require a different balance of nutrients than adults, and therefore may eat foods which a more mature tortoise would not. For example, it is common that the young of a strictly herbivorous species will consume worms or insect larvae for additional protein.

LifespanEdit

File:DesertTortoise.JPG

There are many old wives tales about the age of turtles and tortoises, one of which being that the age of a tortoise can be deduced by counting the number of concentric rings on its carapace, much like the cross-section of a tree. This is not true, since the growth of a tortoise depends highly on the access of food and water. A tortoise that has access to plenty of forage (or is regularly fed by its owner) will grow faster than a Desert Tortoise that goes days without eating.

Tortoises generally have lifespans comparable with those of human beings, and some individuals are known to have lived longer than 150 years. Because of this, they symbolize longevity in some cultures, such as China. The oldest tortoise ever recorded, almost the oldest individual animal ever recorded, was Tu'i Malila, who was presented to the Tongan royal family by the British explorer Captain Cook shortly after its birth in 1777. Tui Malila remained in the care of the Tongan royal family until its death by natural causes on May 19, 1965. This means that upon its death, Tui Malila was 188 years old.[3] The record for the longest-lived vertebrate is exceeded only by one other, a koi named Hanako whose death on July 17, 1977 ended a 215 year life span.[4]

The Alipore Zoo in India was the home to Adwaita, which zoo officials claimed was the oldest living animal until its death on March 23, 2006. Adwaita (sometimes spelled with two d's) was an Aldabra Giant Tortoise brought to India by Lord Wellesley who handed it over to the Alipur Zoological Gardens in 1875 when the zoo was set up. Zoo officials state they have documentation showing that Adwaita was at least 130 years old, but claim that he was over 250 years old (although this has not been scientifically verified). Adwaita was said to be the pet of Robert Clive.[5]

Harriet, a resident at the Australia Zoo in Queensland, was apocryphally thought to have been brought to England by Charles Darwin aboard the Beagle. Harriet died on June 23, 2006, just shy of her 176th birthday.

Timothy, a spur-thighed tortoise, lived to be approximately 165 years old. For 38 years she was carried as a mascot aboard various ships in Britain's Royal Navy. Then in 1892, at age 53 she retired to the grounds of Powderham Castle in Devon. Up to the time of her passing in 2004 she was believed to be the UK's oldest resident.

According to articles published by the Daily Mail and the Times in December 2008, Jonathan, a Seychelles Giant tortoise living on the island of St Helena may be as old as 176[6] or 178 years.[7] If true, he could be the current oldest living animal on Earth.

Sexual dimorphismEdit

Many, though not all, species of tortoises are sexually dimorphic, though the differences between males and females vary from species to species. In some species, males have a longer, more protruding neck plate than their female counterparts, while in others the claws are longer on the females. In most tortoise species, the female tends to be larger than the male. Some believe that males grow quicker, while the female grows slower but larger. The male also has a plastron that is curved inwards to aid reproduction. The easiest way to determine the sex of a tortoise is to look at the tail. The females, as a general rule have a smaller tail which is dropped down whereas the males have a much longer tail which is usually pulled up and to the side of the rear shell.

DietEdit

File:Feeding Tortoise.jpg

Most land based tortoises are herbivores, feeding on grazing grasses, weeds, leafy greens, flowers, and some fruits. Pet tortoises typically require a diet based on alfalfa, clover, dandelions, and some varieties of lettuce. Certain species occasionally consume worms or insects, but too much protein can be detrimental as it can cause shell deformation and other medical problems. Cat or dog foods should not be fed to tortoises, as these do not contain the proper balance of nutrients for a reptile; in particular, they are too high in protein. Additionally, it should not be assumed that all captive tortoises can be fed on the same diet. As different tortoise species vary greatly in their nutritional requirements, even commercial food pellets should be offered only to the species specifically listed on the label or packaging. The best approach to determining the proper diet is to consult a qualified veterinarian, a herpetologist, or a care sheet provided by a reputable source.

TaxonomyEdit

The following species list largely follows Ernst & Barbour (1989), as indicated by The Reptile Database. However, the newly erected genera Astrochelys, Chelonoidis, and Stigmochelys have been retained within Geochelone.

File:SmithTestudoSkeleton.jpg

Tortoises in religionEdit

File:Awatoceanofmilk01.JPG

In Hinduism, Kurma (Sanskrit: कुर्म

) was the second avatar of Vishnu. Like the Matsya Avatara also belongs to the Satya Yuga. Vishnu took the form of a half-man half-tortoise, the lower half being a tortoise. He is normally shown as having four arms. He sat on the bottom of the ocean after the Great Flood. A mountain was placed on his back by the other gods so that they could churn the sea and find the ancient treasures of the Vedic peoples. Tortoise shells were used by ancient Chinese as Oracle Bones to make predictions.

Tortoises in popular cultureEdit

See main article Cultural depictions of turtles and tortoises

GalleryEdit

ReferencesEdit

Further readingEdit

  • Chambers, Paul (2004). A Sheltered Life: The Unexpected History of the Giant Tortoise, London: John Murray.
  • Ernst, C. H.; Barbour, R. W. (1989). Turtles of the World, Washington, DC: Smithsonian Institution Press.
  • Gerlach, Justin (2004). Giant Tortoises of the Indian Ocean, Frankfurt: Chimiara.
  • Kuyl, Antoinette C. van der, et al. (2002). Phylogenetic Relationships among the Species of the Genus Testudo (Testudines: Testudinidae) Inferred from Mitochondrial 12S rRNA Gene Sequences. Molecular Phylogenetics and Evolution 22 (2): 174–183.

External linksEdit

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