Ecology

Associations

Animal / parasite / endoparasite
Angusticaecum holopterum endoparasitises intestine of Testudinidae

Animal / parasite / endoparasite
Atractis dactyluris endoparasitises intestine of Testudinidae
Other: minor host/prey

Animal / parasite / ectoparasite / blood sucker
larva of Hyalomma aegyptium sucks the blood of leg (hind) of Testudinidae
Other: major host/prey

Animal / parasite / endoparasite
Tachygonetria endoparasitises colon of Testudinidae

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Evolution and Systematics

Functional Adaptations

Functional adaptation

Shapes cover curved surfaces efficiently: tortoise
 

The shell of tortoises optimizes material use for a curved surface via hexagonal subunits and filler shapes.

     
  "Inevitably nature is not always exact, despite the precision of the honeycomb. When looking for 120° angles in animal forms it is important to remember another geometric law, which is that flat hexagons will only interlock in a flat plane; they cannot be combined to enclose a space, as can the triangles that constitute the tetrahedron. Where hexagons do occur on curved surfaces -- such as in the beautifully delicate skeletons of some microscopic marine organisms called Radiolaria -- there are always some other shapes and angles inserted to compensate for the curvature. The same is true of the tortoise's shell, where remarkably regular hexagons in the centre are bounded by pentagons (five-sided shapes) which fuse to give a straight edge to the shell; exactly the same happens in insect wings. Three-way junctions also tend to occur where pieces of similar size and shape must be overlapped to cover a surface, as in the feathers of a bird, the scales of a fish, or the scales of a pangolin." (Foy and Oxford Scientific Films 1982:32)
  Learn more about this functional adaptation.
  • Foy, Sally; Oxford Scientific Films. 1982. The Grand Design: Form and Colour in Animals. Lingfield, Surrey, U.K.: BLA Publishing Limited for J.M.Dent & Sons Ltd, Aldine House, London. 238 p.
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
Specimen Records: 101
Specimens with Sequences: 104
Specimens with Barcodes: 98
Species: 34
Species With Barcodes: 34
Public Records: 90
Public Species: 32
Public BINs: 39
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Barcode data

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Wikipedia

Giant tortoise

Giant tortoises are characteristic reptiles of certain tropical islands. Often reaching enormous size—they can weigh as much as 300 kg (660 lbs) and can grow to be 1.3 m (4 ft) long—they live, or lived (some species are recently extinct), in the Seychelles, the Mascarenes and the Galapagos. Today, the world's largest population inhabits Aldabra Atoll in Seychelles, where there are approximately 150,000 individuals. Although appearing similar, the tortoises represent separate branches of evolution. The Seychelles and Mascarenes tortoises derive from nearby Madagascar, while the Galapagos tortoises came from nearby Ecuador.

Although often considered examples of island gigantism, prior to the arrival of Homo sapiens giant tortoises also occurred in non-island locales, as well as on a number of other, more accessible islands. During the Pleistocene, and mostly during the last 50,000 years, tortoises of the mainland of southern Asia (Colossochelys atlas),[1] North[1] and South America,[2] Australia (Meiolania), Indonesia,[1] Madagascar (Dipsochelys),[1] and even the island of Malta[1] became extinct. The giant tortoises formerly of Africa died out somewhat earlier, during the late Pliocene.[3] While the timing of the disappearances of various extinct giant tortoise species seems to correlate with the arrival of humans, direct evidence for human involvement in these extinctions is usually lacking; however, such evidence has been obtained in the case of Meiolania damelipi in Vanuatu.[4][5] One interesting relic is the shell of an extinct giant tortoise found in a submerged sinkhole in Florida with a wooden spear piercing it, carbon dated to 12,000 years ago.[6]

These animals belong to an ancient group of reptiles, appearing about 250 million years ago. In the Upper Cretaceous, 70 or 80 million years ago some already became gigantic. About 1 million years ago tortoises reached the Galápagos Islands. Since 100,000 years ago most of the gigantic species began to disappear. Only 250 years ago there were at least 20 species and subspecies in islands of the Indian Ocean and 14 or 15 subspecies in the Galápagos Islands.

During the 16th and 17th centuries, the Galápagos were frequented by buccaneers preying on Spanish treasure ships. Filling a ship's hold with tortoises was an easy way to stock up on food, a tradition that was continued by whalers in the centuries that followed: "'whaling skippers were almost lyrical in their praise of tortoise meat, terming it far more delicious than chicken, pork or beef'. They said the meat of the giant tortoise was 'succulent meat and the oil from their bodies as pure as butter, but best of all, the giants could hibernate in a ship’s damp for a year or more.'"[7]

Today, only one of the species of the Indian Ocean survives in the wild, the Aldabra giant tortoise (two more are claimed to exist in captive or re-released populations, but some genetic studies have cast doubt on the validity of these as separate species) and 11 subspecies in the Galápagos.

Giant tortoises are among the world's longest-living animals, with an average lifespan of 100 years or more. The Madagascar radiated tortoise Tu'i Malila was 188 at death in Tonga in 1965. Harriet (initially thought to be one of the three Galápagos tortoises brought back to England from Charles Darwin's Beagle voyage but later shown to be from an island not even visited by Darwin) was reported by the Australia Zoo to be 176 years old when she died in 2006. Also, on 23 March 2006, an Aldabra giant tortoise named Adwaita died at Alipore Zoological Gardens in Kolkata. He was brought to the zoo in the 1870s from the estate of Lord Clive and is thought to have been around 255 years old when he died. Around the time of its discovery, they were caught and killed for food in such large quantities that they became virtually extinct by 1900. Giant tortoises are now under strict conservation laws and are categorised as threatened species.

Species and subspecies[edit]

Gallery Galápagos Tortoise Conservation - (Chelonoidis nigra)[edit]

See also[edit]

Notes[edit]

  1. ^ a b c d e Hansen, D. M.; Donlan, C. J.; Griffiths, C. J.; Campbell, K. J. (April 2010). "Ecological history and latent conservation potential: large and giant tortoises as a model for taxon substitutions". Ecography (Wiley) 33 (2): 272–284. doi:10.1111/j.1600-0587.2010.06305.x. Retrieved 2011-02-26. 
  2. ^ Cione, A. L.; Tonni, E. P.; Soibelzon, L. (2003). "The Broken Zig-Zag: Late Cenozoic large mammal and tortoise extinction in South America". Rev. Mus. Argentino Cienc. Nat., n.s. 5 (1): 1–19. ISSN 1514-5158. Retrieved 2011-02-06. 
  3. ^ Harrison, T. (2011). "Tortoises (Chelonii, Testudinidae)". Paleontology and Geology of Laetoli: Human Evolution in Context, Vol. 2: Fossil Hominins and the Associated Fauna. Vertebrate Paleobiology and Paleoanthropology. Springer Science+Business Media. pp. 479–503. doi:10.1007/978-90-481-9962-4_17. ISBN 978-90-481-9961-7. 
  4. ^ White, A. W.; Worthy, T. H.; Hawkins, S.; Bedford, S.; Spriggs, M. (16 August 2010). "Megafaunal meiolaniid horned turtles survived until early human settlement in Vanuatu, Southwest Pacific". Proc. Natl. Acad. Sci. USA 107 (35): 15512–15516. doi:10.1073/pnas.1005780107. Retrieved 2011-08-30. 
  5. ^ Keim, Brandon (17 August 2010). "Extinct, King Koopa-Style Giant Turtle Found on Pacific Island". Wired.  (Popular presentation of some material from the PNAS article)
  6. ^ http://www6.miami.edu/miami-magazine/spring01/time.html
  7. ^ "Floreana History – Pre 1900’s". Diving The Galapagos blog for. DiveTheGalapagos.com. 28 July 2009. Retrieved 2011-02-26. 
  8. ^ Raferty, Isolde. "Lonesome George, last-of-its-kind Galapagos tortoise, dies". MSNBC.com. Retrieved 2012-06-24. 

References[edit]

  • IUCN 2006. 2006 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 20 May 2006.
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Tortoise

Tortoise!<-- This template has to be "warmed up" before it can be used, for some reason -->

Tortoises (Testudinidae) or land turtles are a family of land-dwelling reptiles of the order of Turtles (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 are usually diurnal animals with tendencies to be crepuscular depending on the ambient temperatures. They are generally reclusive animals.

Contents

Use of the term "tortoise"

Adult male tortoise, South Africa

Although the word "tortoise" is used by biologists in reference to the family Testudinidae only, in common usage it is used to describe many land-dwelling turtles. The inclusiveness of the term depends on the variety of English being used.

  • British English normally describes these reptiles as "tortoises" if they live on land.
  • American English tends to use the word "tortoise" for land-dwelling species, including members of Testudinidae, as well as other species such as box tortoises, though use of "turtle" by default is as common.
  • Australian English uses "tortoise" for terrestrial species, including semi-aquatic species that live near ponds and streams. Traditionally a "tortoise" has feet (including webbed feet) while a "turtle" has flippers.

Biology

Birth

Young tortoise

Female tortoises dig nesting burrows in which they lay from one to thirty eggs.[2] 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.[3] 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 carapace and plastron. The plastron of a female tortoise often has a noticeable V-shaped notch below the tail which facilitates 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.

Lifespan

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 accessibility 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, and one of the oldest individual animals ever recorded, was Tu'i Malila, which 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.[4] 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 226 year life span.[5]

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.[6]

Harriet, was a resident at the Australia Zoo in Queensland from 1987 to her death in 2006, it was believed that she was brought to England by Charles Darwin aboard the Beagle and then on to Australia by John Clements Wickham[7][8]. 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[9] or 178 years.[10] If this is true, he could be the current oldest living animal on Earth.

Sexual dimorphism

Many 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.

General information

Giant tortoises move very slowly on dry land, at only 0.17 miles per hour (0.27 km/h).[11]

Diet

A baby tortoise feeding on lettuce.

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 wild grasses, weeds and certain flowers. Certain species occasionally consume worms or insects, but too much protein is 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 it is essential to thoroughly research the dietary needs of your individual tortoise. Commercial tortoise pellets should not be offered as despite their claims they are not formulated to meet the nutritional needs of any type of tortoise. Large pellets have been known to rupture the oesophagus which begins the onset of choking and can cause a slow painful death. The best approach to determining the proper diet is to consult a qualified veterinarian specialising in chelonian care.

Taxonomy

The following species list largely follows Rhodin et al., 2010[12], this is a work in progress.

Skeleton of a tortoise
Fossil of the extinct Ergilemys insolitus
Achilemys cassouleti, the most primitive testudine[13]

Family Testudinidae Batsch 1788[14]

Subfamily Testudininae

Subfamily Xerobatinae Agassiz, L. 1857.[16]

In religion

The bas-relief from Angkor Wat, Cambodia, shows Samudra manthan-Vishnu in the centre, his turtle avatar Kurma below, asuras and devas to left and right.

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.

Cultural depictions


Gallery

See also

References

  1. ^ Gray, J.E.. "A synopsis of the genera of reptiles and amphibia, with a description of some new species". Annals of Philosophy 2 (10): 193–217. 
  2. ^ Andy Highfield. "Tortoise Trust Egg F.A.Q". Tortoisetrust.org. http://www.tortoisetrust.org/articles/eggfaq.html. Retrieved 2009-04-07. 
  3. ^ Andy Highfield. "Tortoise egg incubation". Tortoisetrust.org. http://www.tortoisetrust.org/articles/eggfaq.html. Retrieved 2009-04-07. 
  4. ^ "Tortoise Believed to Have Been Owned by Darwin Dies at 176 - Science News | Science & Technology | Technology News". FOXNews.com. 2006-06-26. http://www.foxnews.com/story/0,2933,200831,00.html. Retrieved 2009-04-07. 
  5. ^ Hanako
  6. ^ "World | South Asia | 'Clive of India's' tortoise dies". BBC News. 2006-03-23. http://news.bbc.co.uk/1/hi/world/south_asia/4837988.stm. Retrieved 2009-04-07. 
  7. ^ Thomson, S. , S. Irwin , and T. Irwin . 1995. Harriet, the Galapagos tortoise: disclosing one and a half centuries of history. Intermontanus 4 (5):33–35.
  8. ^ Thomson, S. , S. Irwin , and T. Irwin . 1996. Harriet: La tortuga de Galápagos. Reptilia 2 (4):46–49.
  9. ^ Jonathan the 176-year-old tortoise revealed as world's oldest animal in Boer War photo Daily Mail, December 5, 2008
  10. ^ Boer War memento puts years on Jonathan the tortoise. The Times, December 4, 2008
  11. ^ 2003 Grolier Encyclopedia, The Great Book of Knowledge, The Speed of Animals, pp. 278
  12. ^ Anders G.J. Rhodin, Peter Paul van Dijk, John B. Iverson, and H. Bradley Shaffer. 2010. Turtles of the World, 2010 Update: Annotated Checklist of Taxonomy, Synonymy, Distribution, and Conservation Status
  13. ^ http://eobatagur.ifrance.com/pub/claudetong1.pdf
  14. ^ Batsch, A.J.G.C. 1788. Versuch einer Anleitung zur Kenntniss und Geschichte der Thiere und Mineralien. Erster Theil. Allgemeine Geschichte der Natur; besondre der Säugthiere, Vögel, Amphibien und Fische. Jena: Akademischen Buchandlung, 528 pp.
  15. ^ Austin, J.J., Arnold, E.N. 2001 Ancient mitochondrial DNA and morphology elucidate an extinct island radiation of Indian Ocean giant tortoises (Cylindraspis). Proceedings: Biological Sciences, Volume 268, Number 1485, Pages: 2515-2523.
  16. ^ Agassiz, L. 1857. Contributions to the natural history of the United States of America. Vol. 1. Little, Brown and Co., Boston. 452p.

Further reading

  • Chambers, Paul (2004). A Sheltered Life: The Unexpected History of the Giant Tortoise. London: John Murray. ISBN 0719565286. 
  • 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, AC; Ph Ballasina, DL; Dekker, JT; Maas, J; Willemsen, RE; Goudsmit, J; et al. (Feb 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. doi:10.1006/mpev.2001.1052. ISSN 1055-7903. PMID 11820839. 
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