Tortoises ( ) are reptiles of the family Testudinidae of the order Testudines (Latin for "tortoise"). Like other testudines, tortoises have a turtle 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 backward into the shell to protect them.
Tortoises can vary in size with some species, such as the Galápagos giant tortoise, growing to more than in length, whereas others like the speckled Cape tortoise have shells that measure only long.
Terminology
Differences exist in usage of the common terms
turtle, tortoise, and
terrapin, depending on the variety of English being used; usage is inconsistent and contradictory.
[Simoons, Frederick J. (1991). Food in China: A Cultural and Historical Inquiry. CRC Press. . p. 358.] These terms are common names and do not reflect precise biological or taxonomic distinctions.
[Burton, Maurice and Burton, Robert (2002). International Wildlife Encyclopedia. Marshall Cavendish. . p. 2796.] American Society of Ichthyologists and Herpetologists 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; tortoise is used only in reference to terrestrial turtles or, more narrowly, only those members of Testudinidae, 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 diamondback terrapin (
Malaclemys terrapin).
[Orenstein, Ronald Isaac (2001). Turtles, Tortoises and Terrapins: Survivors in Armor. Firefly Books. ][ What is the difference between turtles, terrapins, and tortoises? , North Carolina Aquariums (July 1997).][Dawkins, Richard (2009). . Free Press. . p. 174.] In America, for example, the members of the genus
Terrapene dwell on land, yet are referred to as
rather than tortoises.
British and International English usage, by contrast, tends not to use "turtle" as a generic term for all members of the order, and also applies the term "tortoises" broadly to all land-dwelling members of the order Testudines, regardless of whether they are actually members of the family Testudinidae.[ Endangered Wildlife and Plants of the World, Vol. 1. Marshall Cavenish. (2001). . p. 1476.]
Australian usage is different from both American and British usage.[Romanowski, Nick (2010). Wetland Habitats: A Practical Guide to Restoration and Management. CSIRO Publishing. . p. 134.] 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.
Biology
Life cycle
Most species of tortoises lay small clutch sizes, seldom exceeding 20 eggs, and many species have clutch sizes of only 1–2 eggs. Incubation is characteristically long in most species, the average incubation period are between 100 and 160.0 days. 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.
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. They are hatched with an embryonic egg sac which serves as a source of nutrition for the first three to seven days until they have the strength and mobility to find food. Juvenile tortoises often require a different balance of nutrients than adults, so may eat foods which a more mature tortoise would not. For example, the young of a strictly
herbivory species commonly will consume
or insect
for additional protein.
The number of concentric rings on the carapace, much like the cross-section of a tree, can sometimes give a clue to how old the animal is, but, since the growth 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) with no seasonal variation will have no noticeable rings. Moreover, some tortoises grow more than one ring per season, and in some others, due to wear, some rings are no longer visible.
Tortoises generally have one of the longest lifespans of any animal, and some individuals are known to have lived longer than 150 years.
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 (also spelled Addwaita) 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. West Bengal officials said records showed Adwaita was at least 150 years old, but other evidence pointed to 250. Adwaita was said to be the pet of Robert Clive.
Harriet was a resident at the Australia Zoo in Queensland from 1987 to her death in 2006; she was believed to have been brought to England by Charles Darwin aboard the HMS Beagle and then on to Australia by John Clements Wickham.
Timothy, a female spur-thighed tortoise, lived to be about 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 death in 2004, she was believed to be the United Kingdom's oldest resident.
Jonathan, a Seychelles giant tortoise living on the island of St Helena, may be as old as years.[ Meet Jonathan, St Helena's 182-year-old giant tortoise BBC, March 13, 2014]
DNA analysis of the of the long-lived tortoises, Lonesome George, the iconic last member of Chelonoidis abingdonii, and the Aldabra giant tortoise Aldabrachelys gigantea led to the detection of lineage-specific variants affecting DNA repair genes that might contribute to their long lifespan.
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.
The male plastron 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 smaller tails, dropped down, whereas the males have much longer tails which are usually pulled up and to the side of the rear shell.
Brain
The brain of a tortoise is extremely small. Red-footed tortoises, from Central and South America, do not have an area in the brain called the
hippocampus, which relates to emotion, learning, memory and spatial navigation. Studies have shown that red-footed tortoises may rely on an area of the brain called the medial cortex for emotional actions, an area that humans use for actions such as decision making.
Distribution
Tortoises are found from southern North America to southern South America, around the Mediterranean basin, across Eurasia to Southeast Asia, in sub-Saharan Africa, Madagascar, and some Pacific islands. They are absent from
Australasia. They live in diverse habitats, including deserts, arid grasslands, and scrub to wet evergreen forests, and from sea level to mountains. Most species, however, occupy semiarid habitats.
Many large islands are or were characterized by species of . Part of the reason for this is that tortoises are good at oceanic dispersal. Despite being unable to swim, tortoises are able to survive long periods adrift at sea because they can survive months without food or fresh water. Tortoises have been known to survive oceanic dispersals of more than 740 km.
Today there are only two living species of giant tortoises, the Aldabra giant tortoise on Aldabra Atoll and the dozen subspecies of Galapagos giant tortoise found on the Galapagos Islands. However, until recently could be found on nearly every major island group, including the Bahamas, the Greater Antilles (including Cuba and Hispaniola), the Lesser Antilles, the , Malta, the Seychelles, the Mascarene Islands (including Mauritius and Reunion), and Madagascar. Most of these tortoises were wiped out by human arrival. Many of these giant tortoises are not closely related (belonging to different genera such as Megalochelys, Chelonoidis, Centrochelys, Aldabrachelys, Cylindraspis, and Hesperotestudo), but are thought to have independently evolved large body size through convergent evolution. Giant tortoises are notably absent from Australasia and many south Pacific islands, but the distantly related Meiolaniidae stem turtles are thought to have filled the same niche. are also known from the Oligocene-Pliocene of mainland North America, South America, Europe, Asia, and Africa, but are all now extinct, which is also attributed to human activity.
Diet
Tortoises are generally considered to be strict
herbivory, feeding on grasses, weeds, leafy greens, flowers, and some fruits. However, hunting and eating of birds has been observed on occasion.
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. Different tortoise species vary greatly in their nutritional requirements.
Behavior
Communication in tortoises is different from many other reptiles. Because they are restricted by their shell and short limbs, visual communication is not a strong form of communication in tortoises. Tortoises use
Olfaction to determine the sex of other tortoises so that they can find a potential mate. Tactile communication is important in tortoises during combat and courtship. In both combat and courtship, tortoises use ramming to communicate with other individuals.
Taxonomy
This species list largely follows Turtle Taxonomy Working Group (2021)
and the Turtle Extinctions Working Group (2015).
(
Seychelles).]] (
Astrochelys radiata)]]
Family Testudinidae Batsch 1788
[August 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.]
-
Alatochelon
-
Aldabrachelys Loveridge and Williams 1957:166
-
Aldabrachelys gigantea Aldabra giant tortoise.
-
A. g. gigantea Aldabra tortoise.
-
A. g. arnoldi Arnold's giant tortoise.
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A. g. daudinii Daudin's giant tortoise.
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A. g. hololissa Domed Seychelles giant tortoise.
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Extinction Aldabrachelys abrupta Late Holocene, extinct circa 1200 AD
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Extinction Aldabrachelys grandidieri Late Holocene, extinct circa 884 AD
-
( Chelonoidis carbonarius)]] ( Chelonoidis niger)]] Astrochelys Gray, 1873:4
-
Astrochelys radiata, radiated tortoise
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angonoka, angonoka tortoise, (Madagascan) plowshare tortoise
-
Centrochelys Gray 1872:5
[Gray, John Edward. (1872). "Appendix to the Catalogue of Shield Reptiles in the Collection of the British Museum. Part I. Testudinata (Tortoises)". London: British Museum, 28 pp.]
-
Centrochelys atlantica
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Centrochelys burchardi Tenerife giant tortoise
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Centrochelys marocana
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Centrochelys robusta Maltese giant tortoise
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Centrochelys sulcata, African spurred tortoise, sulcata tortoise
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Centrochelys vulcanica Gran Canaria giant tortoise
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Chelonoidis Fitzinger 1835:112
[
]
-
Chelonoidis alburyorum Abaco tortoise, Late Pleistocene, extinct c. 1400 CE
-
Chelonoidis carbonarius, red-footed tortoise
-
Chelonoidis chilensis, Chaco tortoise, Argentine tortoise or southern wood tortoise
-
Chelonoidis cubensis Cuban giant tortoise
-
Chelonoidis denticulatus Brazilian giant tortoise, yellow-footed tortoise
-
C. dominicensis Dominican giant tortoise
-
Chelonoidis lutzae Lutz's giant tortoise, Late Pleistocene
-
Chelonoidis monensis Mona tortoise
-
( Chersina angulata)]] Chelonoidis niger Galapagos giant tortoise
[ Testudinidae, The Reptile Database]
-
Chelonoidis sellovii Southern Cone giant tortoise, Pleistocene
-
Chelonoidis sombrerensis Sombrero giant tortoise, Late Pleistocene
-
( Chersobius signatus)]] Chersina Gray 1830:5
-
Chersina angulata, angulated tortoise, South African bowsprit tortoise
-
Cheirogaster Bergounioux 1935:78
-
† Cheirogaster gymnesica Late Pliocene to Early Pleistocene
-
† Cheirogaster schafferi Pliocene to Early Pleistocene
-
'' fossil]] Chersobius Fitzinger, 1835
-
Chersobius boulengeri, Karoo padloper, Karoo dwarf tortoise, Boulenger's Cape tortoise
-
Chersobius signatus, speckled padloper tortoise
-
Chersobius solus, Nama padloper, Berger's Cape tortoise
-
† Cylindraspis Fitzinger 1835:112
-
† Cylindraspis indica, synonym Cylindraspis borbonica, Reunion giant tortoise
-
† Cylindraspis inepta, saddle-backed Mauritius giant tortoise or Mauritius giant domed tortoise
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† Cylindraspis peltastes, domed Rodrigues giant tortoise
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† Cylindraspis triserrata, domed Mauritius giant tortoise or Mauritius giant flat-shelled tortoise
-
† Cylindraspis vosmaeri, saddle-backed Rodrigues giant tortoise
-
( Geochelone elegans)]] Ergilemys Ckhikvadze, 1984
-
Ergilemys bruneti
-
Ergilemys insolitus
-
Ergilemys saikanensis
-
( Gopherus polyphemus)]] Geochelone Fitzinger 1835:112
-
Geochelone elegans, Indian star tortoise
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Geochelone platynota, Burmese star tortoise
-
Gopherus Rafinesque 1832:64
-
Desert tortoise, Mojave desert tortoise, Agassiz's desert tortoise
-
Texas tortoise, Texas tortoise, Berlandier's tortoise
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Bolson tortoise, Bolson tortoise
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Gopherus morafkai, Sonoran desert tortoise, Morafka's desert tortoise
-
Gopherus polyphemus, gopher tortoise
-
Gopherus evgoodei, Sinaloan desert tortoise, Goode's thornscrub tortoise
-
Hadrianus
-
Hadrianus corsoni (syn. H. octonarius)
-
Hadrianus robustus
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Hadrianus schucherti
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Hadrianus utahensis
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Hesperotestudo
-
Hesperotestudo alleni
-
Hesperotestudo angusticeps
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Hesperotestudo brontops
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Hesperotestudo equicomes
-
Hesperotestudo impensa
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Hesperotestudo incisa
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Hesperotestudo johnstoni
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Hesperotestudo kalganensis
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Hesperotestudo niobrarensis
-
Hesperotestudo orthopygia
-
Hesperotestudo osborniana
-
Hesperotestudo percrassa
-
Hesperotestudo riggsi
-
Hesperotestudo tumidus
-
Hesperotestudo turgida
-
Hesperotestudo wilsoni
-
( Homopus areolatus)]] Homopus Duméril and Bibron 1834:357
[Duméril, André Marie Constant and Bibron, Gab riel. 1834. Erpétologie Générale ou Histoire Naturelle Complète des Reptiles. Tome Premier. Paris: Roret, 439 pp.]
-
Homopus areolatus, common padloper, parrot-beaked tortoise, beaked Cape tortoise
-
Homopus femoralis, greater padloper, greater dwarf tortoise
-
( Indotestudo elongata)]] Indotestudo Lindholm, 1929
-
Indotestudo elongata, elongated tortoise, yellow-headed tortoise
-
Indotestudo forstenii, Forsten's tortoise, East Indian tortoise
-
Indotestudo travancorica, Travancore tortoise
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( Kinixys lobatsiana)]] Kinixys
-
Kinixys belliana, Bell's hinge-back tortoise
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Kinixys erosa, forest hinge-back tortoise, serrated hinge-back tortoise
-
Kinixys homeana, Home's hinge-back tortoise
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Kinixys lobatsiana, Lobatse hinge-back tortoise
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Kinixys natalensis, Natal hinge-back tortoise
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Kinixys spekii, Speke's hinge-back tortoise
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Malacochersus Lindholm 1929:285
-
( Manouria impressa)]] Manouria Gray 1854:133
-
Manouria emys, Asian giant tortoise, brown tortoise (mountain tortoise)
-
Manouria impressa, impressed tortoise
-
Megalochelys Falconer, H. and Cautley, P.T. 1837.
-
Megalochelys atlas, Atlas tortoise, Extinct – Pliocene to Pleistocene
-
Megalochelys cautleyi, Cautley's giant tortoise
-
( Psammobates tentorius)]]'' ]] Psammobates Fitzinger 1835:113
-
Psammobates geometricus, geometric tortoise
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Psammobates oculifer, serrated tent tortoise, Kalahari tent tortoise
-
Psammobates tentorius, African tent tortoise
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Pyxis Bell 1827:395
-
spider tortoise, (Madagascan) spider tortoise
-
Pyxis planicauda, flat-backed spider tortoise, (Madagascan) flat-tailed tortoise, flat-tailed spider tortoise
-
Stigmochelys Gray, 1873
-
Stylemys
-
Titanochelon
-
Titanochelon gymnesica (Bate, 1914) Balearic Islands, Pliocene
-
Titanochelon bolivari (Hernandez-Pacheco, 1917) (type) Iberian Peninsula, Miocene
-
Titanochelon bacharidisi (Vlachos et al., 2014) Greece, Bulgaria, Late Miocene
-
Titanochelon perpiniana (Deperet 1885) France, Pliocene
-
Titanochelon schafferi (Szalai, 1931) Samos, Greece, Miocene
-
Titanochelon vitodurana (Biedermann 1862) Switzerland, Early Miocene
-
Titanochelon kayadibiensis Karl, Staesche & Safi, 2021, Anatolia, Miocene
-
Titanochelon eurysternum (Gervais, 1848–1852) France, Miocene ( Testudo graeca)]]
-
Titanochelon ginsburgi (de Broin, 1977 ) France, Miocene
-
Titanochelon leberonensis (Depéret, 1890) France, Miocene
-
Testudo
-
Testudo graeca, Greek tortoise, spur-thighed tortoise, Moorish tortoise
-
Testudo hermanni, Hermann's tortoise
-
Russian tortoise, Russian tortoise
-
Testudo kleinmanni, Egyptian tortoise, including Negev tortoise
-
Testudo marginata, marginated tortoise
Phylogeny
A molecular phylogeny of tortoises, following Le et al. (2006: 525):
A separate phylogeny via mtDNA analysis was found by Kehlmaier et al. (2021):
In 2023 Kehlmaier again recovered a very similar phylogeny to the 2021 one, which further reaffirmed the evolutionary distinctiveness of the extinct Cylindraspis, but swapped the position of Gopherus and Manouria, making Gopherus the most basal genus.
In human culture
In religion
In
Hinduism,
Kurma () was the second
Avatar of
Vishnu. Like the
Matsya , Kurma 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
deity so they could churn the sea and find the ancient treasures of the
Vedic period peoples.
In Judaism, tortoises are seen as unclean animals.[ Leviticus 11] Early Christians also viewed tortoises as unclean.
In Chinese and Japanese folk religion, tortoises are considered . Tortoise shells were used by ancient Chinese as oracle bones to make predictions.
In Ancient Greek mythology, Hermes crafts the first lyre from a tortoise.
In space: the 1968 trip to the Moon
In September, 1968, two
became the first animals to fly to and circle the Moon. Their Zond 5 mission brought them back to Earth safely.
As pets
As food
Gallery
File:Tortoise-Hatchling.jpg|Baby Testudo marginata emerges from its egg
File:Baby tortoise.jpg|Baby tortoise, less than a day old
File:Tortoise closeup.jpg|Young, 20-year-old leopard tortoise feeding on grass
File:Aldabra.giant.tortoise.arp.jpg|Aldabra giant tortoise, Geochelone gigantea
File:Leopards tortoise.jpg|22-year-old leopard tortoise
File:Geochelone sulcata -Oakland Zoo -feeding-8a.jpg|African spurred tortoise from the Oakland Zoo
File:Tortoise mating.jpg|Pair of African spurred tortoises mate in a zoo
File:TurtleRideIfrog.jpg|Boy rides a tortoise at a zoo
File:Small tortoises mating.webm|Video of tortoises mating
File:Young Hermann's Tortoise.jpg|Young Testudo hermanni
See also
Further reading
External links
