Turtle
Overview
 
Turtles are reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

s of the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Testudines (the crown group
Crown group
A crown group is a group consisting of living representatives, their ancestors back to the most recent common ancestor of that group, and all of that ancestor's descendants. The name was given by Willi Hennig, the formulator of phylogenetic systematics, as a way of classifying living organisms...

 of the superorder Chelonia), characterised by a special bony
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...

 or cartilaginous
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

 shell developed from their rib
Rib
In vertebrate anatomy, ribs are the long curved bones which form the rib cage. In most vertebrates, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax...

s that acts as a shield
Shield
A shield is a type of personal armor, meant to intercept attacks, either by stopping projectiles such as arrows or redirecting a hit from a sword, mace or battle axe to the side of the shield-bearer....

. "Turtle" may either refer to the Testudines as a whole, or to particular Testudines which make up a form taxon
Form taxon
Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships...

 that is not monophyletic.

The order Testudines includes both extant (living) and extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

 species. The earliest known turtles date from 215 million
Million
One million or one thousand thousand, is the natural number following 999,999 and preceding 1,000,001. The word is derived from the early Italian millione , from mille, "thousand", plus the augmentative suffix -one.In scientific notation, it is written as or just 106...

 years ago, making turtles one of the oldest reptile groups and a more ancient group than lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...

s, snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...

s and crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...

s.
Discussions
Encyclopedia
Turtles are reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

s of the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Testudines (the crown group
Crown group
A crown group is a group consisting of living representatives, their ancestors back to the most recent common ancestor of that group, and all of that ancestor's descendants. The name was given by Willi Hennig, the formulator of phylogenetic systematics, as a way of classifying living organisms...

 of the superorder Chelonia), characterised by a special bony
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...

 or cartilaginous
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

 shell developed from their rib
Rib
In vertebrate anatomy, ribs are the long curved bones which form the rib cage. In most vertebrates, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax...

s that acts as a shield
Shield
A shield is a type of personal armor, meant to intercept attacks, either by stopping projectiles such as arrows or redirecting a hit from a sword, mace or battle axe to the side of the shield-bearer....

. "Turtle" may either refer to the Testudines as a whole, or to particular Testudines which make up a form taxon
Form taxon
Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships...

 that is not monophyletic.

The order Testudines includes both extant (living) and extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

 species. The earliest known turtles date from 215 million
Million
One million or one thousand thousand, is the natural number following 999,999 and preceding 1,000,001. The word is derived from the early Italian millione , from mille, "thousand", plus the augmentative suffix -one.In scientific notation, it is written as or just 106...

 years ago, making turtles one of the oldest reptile groups and a more ancient group than lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...

s, snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...

s and crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...

s. Of the many species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 alive today, some are highly endangered
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

.

Like other reptiles, turtles are ectotherm
Ectotherm
An ectotherm, from the Greek εκτός "outside" and θερμός "hot", refers to organisms that control body temperature through external means. As a result, organisms are dependent on environmental heat sources and have relatively low metabolic rates. For example, many reptiles regulate their body...

s—their internal temperature varies according to the ambient environment, commonly called cold-blooded
Poikilotherm
A poikilotherm is an organism whose internal temperature varies considerably. It is the opposite of a homeotherm, an organism which maintains thermal homeostasis. Usually the variation is a consequence of variation in the ambient environmental temperature...

. However, leatherback sea turtle
Leatherback Sea Turtle
The leatherback sea turtle is the largest of all living sea turtles and the fourth largest modern reptile behind three crocodilians. It is the only living species in the genus Dermochelys. It can easily be differentiated from other modern sea turtles by its lack of a bony shell. Instead, its...

s have noticeably higher body temperature than surrounding water because of their high metabolic rate.

Like other amniote
Amniote
The amniotes are a group of tetrapods that have a terrestrially adapted egg. They include synapsids and sauropsids , as well as their fossil ancestors. Amniote embryos, whether laid as eggs or carried by the female, are protected and aided by several extensive membranes...

s (reptiles, dinosaurs, birds, and mammals), they breathe air and do not lay eggs underwater, although many species live in or around water. The largest turtles are aquatic.

Anatomy and morphology

The largest living chelonian is the leatherback sea turtle (Dermochelys coriacea), which reaches a shell length of 200 centimetres (6.6 ft) and can reach a weight of over 900 kilograms (1,984.2 lb). Freshwater turtles are generally smaller, but with the largest species, the Asian softshell turtle Pelochelys cantorii
Pelochelys cantorii
The Cantor's giant softshell turtle or Asian giant softshell turtle is a species of fresh water turtle. The turtle has a broad head and small eyes close to the tip of its snout. The carapace is smooth and olive colored...

, a few individuals have been reported up to 200 centimetres (6.6 ft). This dwarfs even the better-known alligator snapping turtle
Alligator Snapping Turtle
The alligator snapping turtle is one of the largest freshwater turtles in the world. It is not closely related to, but is often associated with the common snapping turtle. They are the sole living member of the genus Macrochelys--while common snappers are in the genus Chelydra...

, the largest chelonian in North America, which attains a shell length of up to 80 centimetres (2.6 ft) and weighs as much as 113.4 kilograms (250 lb).
Giant tortoises of the genera Geochelone
Geochelone
Geochelone is a genus of tortoises.Geochelone tortoises, which are also known as typical tortoises or terrestrial turtles, can be found in Africa and Asia. They primarily eat plants.The genus consists of three extant species:...

, Meiolania
Meiolania
Meiolania is an extinct genus of cryptodire turtle from the Oligocene to Holocene, with the last relict populations at New Caledonia which survived until 2,000 years ago....

, and others were relatively widely distributed around the world into prehistoric times, and are known to have existed in North and South America, Australia, and Africa. They became extinct at the same time as the appearance of man, and it is assumed humans hunted them for food. The only surviving giant tortoise
Giant tortoise
Giant tortoises are characteristic reptiles of certain tropical islands. Often reaching enormous size—they can weigh as much as 300 kg and can grow to be 1.3 m long—they live, or lived , in the Seychelles, the Mascarenes and the Galapagos...

s are on the Seychelles
Seychelles
Seychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar....

 and Galápagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...

, and can grow to over 130 centimetres (51.2 in) in length, and weigh about 300 kilograms (661.4 lb).

The largest ever chelonian was Archelon ischyros
Archelon
Archelon is a genus of extinct sea turtle, the largest that has ever been documented.-Discovery:...

, a Late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 sea turtle known to have been up to 4.6 metres (15 ft) long.

The smallest turtle is the speckled padloper tortoise
Speckled Padloper Tortoise
The speckled padloper or speckled Cape tortoise is the world’s smallest tortoise. It is endemic to South Africa....

 of South Africa. It measures no more than 8 centimetres (3.1 in) in length and weighs about 140 grams (4.9 oz). Two other species of small turtles are the American mud turtle
Mud turtle
The Eastern Mud Turtle, or Kinosternon subrubrum is a small semi-aquatic, generally freshwater turtle. Turtles are members of the phylum Chordata and the class Reptilia. The eastern mud turtle lives in the southeastern parts of the United States...

s and musk turtles
Sternotherus
Sternotherus is a genus of aquatic turtles known commonly as musk turtles.-Description:They are very similar to the American mud turtles, but tend to have a more domed carapace, with a distinctive keel down the center of it...

 that live in an area that ranges from Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

 to South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

. The shell length of many species in this group is less than 13 centimetres (5.1 in) in length.

Neck folding

Turtles are divided into two groups, according to how they evolved a solution to the problem of withdrawing their necks into their shells (something the ancestral Proganochelys
Proganochelys
Proganochelys quenstedti is the second oldest turtle species discovered to date, known only from fossils found in Germany and Thailand in strata from the late Triassic, dating to approximately 210 million years ago...

 could not do): the Cryptodira
Cryptodira
Cryptodira is the taxonomic suborder of Testudines that includes most living tortoises and turtles. Cryptodira differ from Pleurodira in that they lower their necks and pull the heads straight back into the shells; instead of folding their necks sideways along the body under the shells' margins...

, which can draw their necks in while contracting it under their spine; and the Pleurodira
Pleurodira
The Pleurodira are one of the two living suborders of turtles, the other being the Cryptodira. In many cases in the nomenclature of animals, ranks such as suborder are considered of little importance apart from nomenclatural or taxonomic reasons. However, this is not the case with the suborders of...

, which contract their necks to the side.

Head

Most turtles that spend most of their lives on land have their eyes looking down at objects in front of them. Some aquatic turtles, such as snapping turtles and soft-shelled turtles, have eyes closer to the top of the head. These species of turtles can hide from predators in shallow water, where they lie entirely submerged except for their eyes and nostrils. Sea turtles possess glands near their eyes that produce salty tears that rid their body of excess salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

 taken in from the water they drink.

Turtles are thought to have exceptional night vision due to the unusually large number of rod cell
Rod cell
Rod cells, or rods, are photoreceptor cells in the retina of the eye that can function in less intense light than can the other type of visual photoreceptor, cone cells. Named for their cylindrical shape, rods are concentrated at the outer edges of the retina and are used in peripheral vision. On...

s in their retinas. Turtles have color vision with a wealth of cone subtypes with sensitivities ranging from the near ultraviolet (UV A) to red. Some land turtles have very poor pursuit movement abilities, which are normally reserved for predators that hunt quick moving prey, but carnivorous turtles are able to move their heads quickly to snap.

Turtles have a rigid beak. Turtles use their jaw
Jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...

s to cut and chew food. Instead of teeth, the upper and lower jaws of the turtle are covered by horny ridges. Carnivorous turtles usually have knife-sharp ridges for slicing through their prey. Herbivorous turtles have serrated-edged ridges that help them cut through tough plants. Turtles use their tongues to swallow food, but they cannot, unlike most reptiles, stick out their tongues to catch food.

Shell

The upper shell of the turtle is called the carapace. The lower shell that encases the belly is called the plastron. The carapace and plastron are joined together on the turtle's sides by bony structures called bridges. The inner layer of a turtle's shell is made up of about 60 bones that include portions of the backbone and the ribs, meaning the turtle cannot crawl out of its shell. In most turtles, the outer layer of the shell is covered by horny scales called scute
Scute
A scute or scutum is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects.-Properties:...

s that are part of its outer skin, or epidermis. Scutes are made up of a fibrous protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 called keratin
Keratin
Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...

 that also makes up the scales of other reptiles. These scutes overlap the seams between the shell bones and add strength to the shell. Some turtles do not have horny scutes. For example, the leatherback sea turtle and the soft-shelled turtles have shells covered with leathery skin instead.

The rigid shell means turtles cannot breathe as other reptiles do, by changing the volume of their chest cavity via expansion and contraction of the ribs. Instead, turtles breathe in two ways. First, they employ buccal pumping
Buccal pumping
Buccal pumping is a method of respiration in which the animal moves the floor of the mouth in a rhythmic manner that is externally apparent.This method has several stages. These will be described for an animal starting with lungs in a deflated state: First, the glottis is closed, and the...

, pulling air into their mouth, then pushing it into the lungs via oscillations of the floor of the throat. Secondly, by contracting the abdominal muscles that cover the posterior opening of the shell, the internal volume of the shell increases, drawing air into the lungs, allowing these muscles to function in much the same way as the mammalian diaphragm.

The shape of the shell gives helpful clues to how a turtle lives. Most tortoises have a large, dome-shaped shell that makes it difficult for predators to crush the shell between their jaws. One of the few exceptions is the African pancake tortoise
Pancake tortoise
The pancake tortoise is a flat-shelled tortoise native to Tanzania and Kenya. Its name is derived from the flat shape of its shell. It is the only member of the genus Malacochersus.-Description:...

, which has a flat, flexible shell that allows it to hide in rock crevices. Most aquatic turtles have flat, streamlined shells which aid in swimming and diving. American snapping turtles
Chelydridae
Chelydridae is a family of turtles which has seven extinct and two extant genera. The extant genera are Chelydra the snapping turtles, and its larger relative Macrochelys, of which the Alligator Snapping Turtle is the only species. Both are endemic to the Western Hemisphere...

 and musk turtles
Sternotherus
Sternotherus is a genus of aquatic turtles known commonly as musk turtles.-Description:They are very similar to the American mud turtles, but tend to have a more domed carapace, with a distinctive keel down the center of it...

 have small, cross-shaped plastrons that give them more efficient leg movement for walking along the bottom of ponds and streams.

The color of a turtle's shell may vary. Shells are commonly colored brown, black, or olive green. In some species, shells may have red, orange, yellow, or grey markings and these markings are often spots, lines, or irregular blotches. One of the most colorful turtles is the eastern painted turtle
Painted Turtle
The painted turtle is the most widespread native turtle of North America. It lives in slow-moving fresh waters, from southern Canada to Louisiana and northern Mexico, and from the Atlantic to the Pacific. The turtle is the only species of the genus Chrysemys, which is part of the pond turtle...

 which includes a yellow plastron and a black or olive shell with red markings around the rim.

Tortoises, being land-based, have rather heavy shells. In contrast, aquatic and soft-shelled turtles have lighter shells that help them avoid sinking in water and swim faster with more agility. These lighter shells have large spaces called fontanelle
Fontanelle
A fontanelle is an anatomical feature on an infant's skull.-Anatomy:Fontanelles are soft spots on a baby's head which, during birth, enable the bony plates of the skull to flex, allowing the child's head to pass through the birth canal. The ossification of the bones of the skull causes the...

s between the shell bones. The shells of leatherback sea turtles are extremely light because they lack scutes and contain many fontanelles.

Skin and molting

As mentioned above, the outer layer of the shell is part of the skin; each scute (or plate) on the shell corresponds to a single modified scale. The remainder of the skin is composed of skin with much smaller scales, similar to the skin of other reptiles. Turtles do not molt their skins all at once, as snakes do, but continuously, in small pieces. When kept in aquaria, small sheets of dead skin can be seen in the water (often appearing to be a thin piece of plastic) having been sloughed off when the animal deliberately rubs itself against a piece of wood or stone. Tortoises also shed skin, but a lot of dead skin is allowed to accumulate into thick knobs and plates that provide protection to parts of the body outside the shell.

By counting the rings formed by the stack of smaller, older scutes on top of the larger, newer ones, it is possible to estimate the age of a turtle, if one knows how many scutes are produced in a year. This method is not very accurate, partly because growth rate is not constant, but also because some of the scutes eventually fall away from the shell.

Limbs

Terrestrial tortoises have short, sturdy feet. Tortoises are famous for moving slowly, in part because of their heavy, cumbersome shell, which restricts stride length.

The amphibious turtles normally have limbs similar to those of tortoises, except the feet are webbed and often have long claw
Claw
A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...

s. These turtles swim using all four feet in a way similar to the dog paddle, with the feet on the left and right side of the body alternately providing thrust. Large turtles tend to swim less than smaller ones, and the very big species, such as alligator snapping turtles, hardly swim at all, preferring to simply walk along the bottom of the river or lake. As well as webbed feet, turtles have very long claws, used to help them clamber onto riverbanks and floating logs, upon which they like to bask
Ectotherm
An ectotherm, from the Greek εκτός "outside" and θερμός "hot", refers to organisms that control body temperature through external means. As a result, organisms are dependent on environmental heat sources and have relatively low metabolic rates. For example, many reptiles regulate their body...

. Male turtles tend to have particularly long claws, and these appear to be used to stimulate the female while mating. While most turtles have webbed feet, some, such as the pig-nosed turtle, have true flippers, with the digits being fused into paddles and the claws being relatively small. These species swim in the same way as sea turtles (see below).

Sea turtles are almost entirely aquatic and have flippers
Flipper (anatomy)
A flipper is a typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example penguins , cetaceans A flipper is a typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example penguins (also called...

 instead of feet. Sea turtles fly through the water, using the up-and-down motion of the front flippers to generate thrust; the back feet are not used for propulsion, but may be used as rudder
Rudder
A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...

s for steering. Compared with freshwater turtles, sea turtles have very limited mobility on land, and apart from the dash from the nest to the sea as hatchlings, male sea turtles normally never leave the sea. Females must come back onto land to lay eggs. They move very slowly and laboriously, dragging themselves forwards with their flippers.

Ecology and life history

Although many turtles spend large amounts of their lives underwater, all turtles and tortoises breathe air, and must surface at regular intervals to refill their lungs. They can also spend much of their lives on dry land. Aquatic respiration in Australian freshwater turtles is currently being studied. Some species have large cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...

l cavities that are lined with many finger-like projections. These projections, called papillae, have a rich blood supply, and increase the surface area of the cloaca. The turtles can take up dissolved oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 from the water using these papillae, in much the same way that fish use gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

s to respire.

Turtles lay eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

, like other reptiles, which are slightly soft and leathery. The eggs of the largest species are spherical, while the eggs of the rest are elongated. Their albumen is white and contains a different protein from bird eggs, such that it will not coagulate when cooked. Turtle eggs prepared to eat consist mainly of yolk. In some species, temperature determines whether an egg develops into a male or a female
Temperature-dependent sex determination
Temperature-dependent sex determination is type of environmental sex determination in which the temperatures experienced during embryonic development determine the sex of the offspring. It is most prevalent and common among amniote vertebrates that are classified under the reptile class, but is...

: a higher temperature causes a female, a lower temperature causes a male. Large numbers of eggs are deposited in holes dug into mud or sand. They are then covered and left to incubate by themselves. When the turtles hatch, they squirm their way to the surface and head toward the water. There are no known species in which the mother cares for the young.

Sea turtles lay their eggs on dry, sandy beaches. Immature sea turtles are not cared for by the adults. Turtles can take many years to reach breeding age, and in many cases breed every few years rather than annually.

Researchers have recently discovered a turtle’s organs do not gradually break down or become less efficient over time, unlike most other animals. It was found that the liver, lungs, and kidneys of a centenarian turtle are virtually indistinguishable from those of its immature counterpart. This has inspired genetic researchers to begin examining the turtle genome for longevity genes.

Systematics and evolution

The first proto-turtles are believed to have existed in the late Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

 Period of the Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...

 era, about 220 million years ago, and their shell, which has remained a remarkably stable body plan
Body plan
A body plan is the blueprint for the way the body of an organism is laid out. An organism's symmetry, its number of body segments and number of limbs are all aspects of its body plan...

, is thought to have evolved from bony extensions of their backbones and broad ribs that expanded and grew together to form a complete shell that offered protection at every stage of its evolution, even when the bony component of the shell was not complete. This is supported by fossils of the freshwater Odontochelys semitestacea or "half-shelled turtle with teeth", from the late Triassic, which have been found near Guangling in southwest China. Odontochelys displays a complete bony plastron and an incomplete carapace, similar to an early stage of turtle embryonic development. Prior to this discovery, the earliest-known fossil turtles were terrestrial and had a complete shell, offering no clue to the evolution of this remarkable anatomical feature. By the late Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

, turtles had radiated widely, and their fossil history becomes easier to read.

Their exact ancestry has been disputed. It was believed they are the only surviving branch of the ancient evolutionary grade
Evolutionary grade
In alpha taxonomy, a grade refers to a taxon united by a level of morphological or physiological complexity. The term was coined by British biologist Julian Huxley, to contrast with clade, a strictly phylogenetic unit.-Definition:...

 Anapsid
Anapsid
An anapsid is an amniote whose skull does not have openings near the temples.While "anapsid reptiles" or "anapsida" are traditionally spoken of as if they were a monophyletic group, it has been suggested that several groups of reptiles that had anapsid skulls may be only distantly related...

a, which includes groups such as procolophonid
Procolophonid
The Procolophonids - family Procolophonidae - are a group of small reptiles. Skulls have been discovered, roughly 5 cm in diameter....

s, millerettid
Millerettid
The millerettids are an extinct group of anapsids that lived in South Africa during the Upper Permian. They were small insectivores and probably resembled modern lizards in appearance and lifestyle.-External links:*...

s, protorothyrids
Protorothyrididae
Protorothyrididae is a family of small, lizard-like reptiles. Their skulls did not have fenestrae, as is also true of modern turtles and tortoises. Protorothyridids lived from the Late Carboniferous to Early Permian periods, in what is now North America. Many genera of primitive reptiles were...

, and pareiasaur
Pareiasaur
The Pareiasaurs - Family Pareiasauridae - are a clade of medium-sized to large herbivorous anapsid reptiles that flourished during the Permian period....

s. All anapsid skulls lack a temporal opening, while all other extant amniote
Amniote
The amniotes are a group of tetrapods that have a terrestrially adapted egg. They include synapsids and sauropsids , as well as their fossil ancestors. Amniote embryos, whether laid as eggs or carried by the female, are protected and aided by several extensive membranes...

s have temporal openings (although in mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s the hole has become the zygomatic arch
Zygomatic arch
The zygomatic arch or cheek bone is formed by the zygomatic process of temporal bone and the temporal process of the zygomatic bone , the two being united by an oblique suture; the tendon of the Temporalis passes medial to the arch to gain insertion into the coronoid process...

). The millerettids, protorothyrids, and pareiasaurs became extinct in the late Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

 period, and the procolophonoids during the Triassic.

However, it was later suggested the anapsid-like turtle skull may be due to reversion
Reversion
Reversion may refer to:*Reversion *Reversion *Reversion *Reversion *Series reversion, in mathematics*Reversion, in evolutionary biology...

 rather than to anapsid descent. More recent morphological phylogenetic
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...

 studies with this in mind placed turtles firmly within diapsid
Diapsid
Diapsids are a group of reptiles that developed two holes in each side of their skulls, about 300 million years ago during the late Carboniferous period. Living diapsids are extremely diverse, and include all crocodiles, lizards, snakes, and tuatara...

s, slightly closer to Squamata
Squamata
Squamata, or the scaled reptiles, is the largest recent order of reptiles, including lizards and snakes. Members of the order are distinguished by their skins, which bear horny scales or shields. They also possess movable quadrate bones, making it possible to move the upper jaw relative to the...

 than to Archosaur
Archosaur
Archosaurs are a group of diapsid amniotes whose living representatives consist of modern birds and crocodilians. This group also includes all extinct non-avian dinosaurs, many extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most...

ia. All molecular studies have strongly upheld the placement of turtles within diapsids; some place turtles within Archosauria, or, more commonly, as a sister group to extant archosaurs. Reanalysis of prior phylogenies suggests they classified turtles as anapsids both because they assumed this classification (most of them studying what sort of anapsid turtles are) and because they did not sample fossil and extant taxa broadly enough for constructing the cladogram
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...

. Testudines were suggested to have diverged from other diapsids between 200 and 279 million years ago, though the debate is far from settled.

The earliest known fully shelled turtle is the late-Triassic Proganochelys
Proganochelys
Proganochelys quenstedti is the second oldest turtle species discovered to date, known only from fossils found in Germany and Thailand in strata from the late Triassic, dating to approximately 210 million years ago...

. The genus species already had many advanced turtle traits, and thus probably had many millions of years of preceding turtle evolution and species in its ancestry. It did lack the ability to pull its head into its shell (and it had a long neck), and had a long, spiked tail ending in a club, a body form similar to that of ankylosaurs, resulting from convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...

.

Turtles are divided into two extant suborders, the Cryptodira
Cryptodira
Cryptodira is the taxonomic suborder of Testudines that includes most living tortoises and turtles. Cryptodira differ from Pleurodira in that they lower their necks and pull the heads straight back into the shells; instead of folding their necks sideways along the body under the shells' margins...

 and the Pleurodira
Pleurodira
The Pleurodira are one of the two living suborders of turtles, the other being the Cryptodira. In many cases in the nomenclature of animals, ranks such as suborder are considered of little importance apart from nomenclatural or taxonomic reasons. However, this is not the case with the suborders of...

. The Cryptodira is the larger of the two groups and includes all the marine turtles, the terrestrial tortoises, and many of the freshwater turtles. The Pleurodira are sometimes known as the side-necked turtles, a reference to the way they withdraw their heads into their shells. This smaller group consists primarily of various freshwater turtles.

Turtle genera with basal or uncertain phylogenetic position

  • Genus †Australochelys (Chelonia incertae sedis)
  • Genus †Murrhardtia (Chelonia incertae sedis)
  • Genus †Palaeochersis (Chelonia incertae sedis)
  • Genus †Chinlechelys (Proganochelydia or basal Testudines)
  • Genus †Chelycarapookus (Testudines incertae sedis)
  • Genus †Chitracephalus (Testudines incertae sedis)
  • Genus †Neusticemys (Testudines incertae sedis)
  • Genus †Scutemys (Testudines incertae sedis)

Suborder †Proganochelydia

  • Genus †Odontochelys
    Odontochelys
    Odontochelys semitestacea is an extinct turtle species, the oldest known one. It is the only known species in the genus Odontochelys and the family Odontochelyidae. O. semitestacea was first described from three 220 million year-old specimens excavated in Triassic deposits in Guizhou,...

     (tentatively placed here)
  • Genus †Proganochelys
    Proganochelys
    Proganochelys quenstedti is the second oldest turtle species discovered to date, known only from fossils found in Germany and Thailand in strata from the late Triassic, dating to approximately 210 million years ago...


Suborder Cryptodira

Basal genera
  • Genus †Kayentachelys
    Kayentachelys
    Kayentachelys is an extinct genus of cryptodire turtle from the Early Jurassic Kayenta Formation of northern Arizona. Kayentachelys was approximately wide and in length. It lived in an environment dominated by streams and dunes....

  • Genus †Indochelys

Infraorder †Paracryptodira
Paracryptodira
The Paracryptodira are an extinct infraorder of the Testudines, an order of reptiles which includes tortoises, turtles and terrapins. Initially treated as suborder sister to the Cryptodira, they are now known to be a very primitive lineage inside the Cryptodira according to the most common use of...

  • Basal and incertae sedis
    • Family †Kallokibotiidae
    • Family †Mongolochelyidae
    • Family †Pleurosternidae
    • Family †Solemydidae
  • Superfamily †Baenoidea
    • Family †Baenidae
      Baenidae
      Baenidae is an extinct family of cryptodiran turtles.-External links:* http://www.nhm.org/site/sites/default/files/dinosaur_institute/pdf/NHM_DI_proytecto_dino_Erika_Canola_Baenidae_Turtle_experience.pdf...

    • Family †Macrobaenidae
    • Family †Neurankylidae

Infraorder Eucryptodira
  • Basal and incertae sedis
    • †"Sinemys" wuerhoensis
    • Genus †Chubutemys (Meiolaniidae?)
    • Genus †Hangaiemys (Macrobaenidae?)
    • Genus †Judithemys
    • Genus †Osteopygis
    • Genus †Planetochelys
    • Family Chelydridae
      Chelydridae
      Chelydridae is a family of turtles which has seven extinct and two extant genera. The extant genera are Chelydra the snapping turtles, and its larger relative Macrochelys, of which the Alligator Snapping Turtle is the only species. Both are endemic to the Western Hemisphere...

       (snapping turtles)
    • Family †Eurysternidae
    • Family †Macrobaenidae
    • Family †Meiolaniidae
      Meiolaniidae
      Meiolaniidae is an extinct family of large, possibly herbivorous turtles with heavily armored heads and tails. They are best known from the last surviving genus, Meiolania, which lived in the rainforests of Australia from the Oligocene until the Pleistocene, and relict populations that lived on...

       (horned turtles)
    • Family †Plesiochelyidae
    • Family †Sinemydidae
    • Family †Xinjiangchelyidae
  • Superfamily Chelonioidea (sea turtles)
    • Family †Protostegidae
      Protostegidae
      Protostegidae is a family of extinct marine turtles that lived during the Mesozoic Era. The family includes some of the largest sea turtles that ever existed. The largest, Archelon, had a head a meter long...

    • Family †Thalassemyidae
    • Family †Toxochelyidae 
    • Family Cheloniidae
      Cheloniidae
      Cheloniidae is a family of turtles belonging to the sea turtle superfamily Chelonioidea.-Extant genera:*Genus Caretta**Loggerhead sea turtle *Genus Chelonia**Green sea turtle *Genus Eretmochelys...

       (green sea turtles and relatives)
    • Family Dermochelyidae
      Dermochelyidae
      Dermochelyidae is a family of turtles which has eight extinct and one extant genera.-Classification of known genera:*Subfamily Desmatochelyinae** Corochelys ** Desmatochelys *Subfamily Allopleuroninae ** Allopleuron ** Eosphargis...

       (leatherback sea turtles)
  • Superfamily Testudinoidea
    Testudinoidea
    Testudinoidea is a superfamily within the suborder Cryptodira of the order Testudines. It includes the families of pond turtles ; Asian turtles ; the Big-headed turtle and tortoises ....

    • Family †Haichemydidae
    • Family †Lindholmemydidae
    • Family †Sinochelyidae
    • Family Platysternidae (big-headed turtle)
    • Family Emydidae
      Emydidae
      Emydidae, commonly called the pond turtles or marsh turtles, is a family of turtles. Previously, several species of Asian box turtle were classified in the family. However, revised taxonomy has separated them to a different family. Now, Emydidae, with the exception of two species of pond turtle,...

       (pond
      Pond turtle
      Pond turtle may refer to:* Emydidae, a family of pond turtles** Emys, a genus of Emydidae*** European pond turtle *** Sicilian pond turtle *** Western pond turtle...

      , box
      Box turtle
      The box turtle , or box tortoise is a genus of turtle native to North America . The 12 taxa which are distinguished in the genus are distributed over four species. It is largely characterized by having a domed shell, which is hinged at the bottom, allowing the animal to close its shell tightly to...

       and water turtles)
    • Family Geoemydidae
      Geoemydidae
      Geoemydidae is the largest and most diverse family in the order Testudines with about 70 species. It includes the Eurasian pond and river turtles and Neotropical wood turtles.-Characteristics:...

       (Asian river turtles, Asian leaf turtle
      Asian Leaf Turtle
      The Asian leaf turtle Cyclemys dentata is a species of turtle found in Southeast Asia. They are quite common in the pet trade with its carapace resembling that of a Cuora amboinensis hybrid.- Feeding :...

      s, Asian box turtles and roofed turtles)
    • Family Testudinidae (true tortoises)
  • Superfamily Trionychoidea
    Trionychoidea
    Trionychia is a superfamily of turtles which encompasses the species that are commonly referred to as softshelled turtles as well as some others. They are found throughout the temperate regions of the world....

    • Family †Adocidae
    • Family Carettochelyidae (pignose turtles)
    • Family Dermatemydidae (river turtles)
    • Family Kinosternidae
      Kinosternidae
      Kinosternidae is a family of mostly small turtles that includes the mud turtles and musk turtles. The family Kinosternidae contains 25 species within 4 genera, but taxonomic reclassification is an ongoing process so many sources vary on the exact numbers of species and subspecies...

       (mud turtles)
    • Family Trionychidae
      Trionychidae
      Trionychidae is a taxonomic family which comprises a number of turtle genera commonly known as softshells. They are also sometimes called pancake turtles. Softshells consist of some of the world's largest fresh water turtles, though many can adapt to living in highly brackish areas. Members of this...

       (softshell turtles)

Suborder Pleurodira

  • Basal and incertae sedis
    • Family †Araripemydidae
    • Family †Proterochersidae
    • Family Chelidae
      Chelidae
      The Chelidae are one of the three living families of the turtle suborder Pleurodira and are commonly called the Austro-South American Side Neck turtles. The Family is distributed in Australia, New Guinea, parts of Indonesia and throughout most of South America. It is a large family of turtles with...

       (Austro-American sideneck turtles)
  • Superfamily Pelomedusoidea
    • Family †Bothremydidae
      Bothremydidae
      Bothremydidae is an extinct family of side-necked turtle. They belong to sub-order Pleurodira and order Testudines. Bothremydidae lived in fresh water and were amphibious. They were actively mobile omnivores.-Taxonomy:...

    • Family Pelomedusidae
      Pelomedusidae
      Pelomedusidae is a family of freshwater turtles, native to eastern and southern Africa. They range in size from to in shell length, and are generally roundish in shape...

       (African sideneck turtles)
    • Family Podocnemididae
      Podocnemididae
      Podocnemididae is a family of turtles native to Madagascar and northern South America. They are side-necked turtles , which means they do not retract their heads backwards, but hide it sideways....

       (Madagascan big-headed and American sideneck river turtles)

Turtle, tortoise, or terrapin

Although the word turtle is widely used to describe all members of the order Testudines, it is also common to see certain members described as terrapins, tortoises or sea turtles, as well. Precisely how these alternative names are used, if at all, depends on the type of English being used.
  • British English
    British English
    British English, or English , is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere...

     normally describes these reptiles as turtles if they live in the sea; terrapins if they live in fresh or brackish water
    Brackish water
    Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...

    ; or tortoises if they live on land. However, there are exceptions to this where American or Australian common names are in wide use, as with the Fly River turtle.
  • American English
    American English
    American English is a set of dialects of the English language used mostly in the United States. Approximately two-thirds of the world's native speakers of English live in the United States....

     tends to use the word turtle as a general term for all species. "Tortoise" is used for most land-dwelling species, including the family Testudinidae and box tortoises. Oceanic species are usually referred to as sea turtles. The name "terrapin" is typically reserved only for the brackish water diamondback terrapin
    Diamondback terrapin
    The diamondback terrapin or simply terrapin, is a species of turtle native to the brackish coastal swamps of the eastern and southern United States. It belongs to the monotypic genus, Malaclemys...

    , Malaclemys terrapin; the word terrapin being derived from the Algonquian
    Algonquian languages
    The Algonquian languages also Algonkian) are a subfamily of Native American languages which includes most of the languages in the Algic language family. The name of the Algonquian language family is distinguished from the orthographically similar Algonquin dialect of the Ojibwe language, which is a...

     word for this animal.
  • Australian English
    Australian English
    Australian English is the name given to the group of dialects spoken in Australia that form a major variety of the English language....

     uses turtle for both the marine and freshwater species, but tortoise for the terrestrial species.

To avoid confusion, the word "chelonian" is popular among veterinarians, scientists, and conservationists working with these animals as a catch-all name for any member of the superorder Chelonia, which includes all turtles, tortoises and terrapins living and extinct, as well as their immediate ancestors. It is based on the Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

 word χελώνη, chelōnē; Modern Greek
Modern Greek
Modern Greek refers to the varieties of the Greek language spoken in the modern era. The beginning of the "modern" period of the language is often symbolically assigned to the fall of the Byzantine Empire in 1453, even though that date marks no clear linguistic boundary and many characteristic...

 χελώνα, chelōna; meaning turtle/tortoise.

Some languages do not have this problem, as all of these are referred to by the same name. For example, in Spanish
Spanish language
Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...

, the word "tortuga" is used for turtles, tortoises and terrapins, though the type they belong to is usually specified and added to the name, as "marina" for sea turtles, "de río", for freshwater species and "terrestre" for tortoises.

Distribution

Seven species of marine turtles are found worldwide. Of these, five have been recorded in Europe.

Fossil record

Neonate sized turtle fossils have been documented in the scientific literature
Scientific literature
Scientific literature comprises scientific publications that report original empirical and theoretical work in the natural and social sciences, and within a scientific field is often abbreviated as the literature. Academic publishing is the process of placing the results of one's research into the...

.

Genomics

Turtles possess diverse chromosome numbers (2N = 28-66) and a myriad of chromosomal rearrangements have occurred during evolution.

As pets

Turtles, particularly small terrestrial and freshwater turtles, are commonly kept as pets. Among the most popular are Russian tortoise
Russian Tortoise
The Russian tortoise, Horsfield's tortoise or Central Asian tortoise is a species of tortoise that is a popular pet...

s, spur-thighed tortoises, and red-eared slider
Red-eared slider
The red-eared slider is a semiaquatic turtle belonging to the family Emydidae. It is a subspecies of pond slider. It is the most popular pet turtle in the United States and also popular in the rest of the world...

s.

In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, due to the ease of contracting salmonellosis
Salmonellosis
Salmonellosis is an infection with Salmonella bacteria. Most people infected with Salmonella develop diarrhea, fever, vomiting, and abdominal cramps 12 to 72 hours after infection. In most cases, the illness lasts four to seven days, and most people recover without treatment...

 through casual contact with turtles, the U.S. Food and Drug Administration (FDA) established a regulation in 1975 to discontinue the sale of turtles under 4 inches.
It is illegal in every state in the U.S. for anyone to sell any turtles under 4 inches (10.2 cm) long. Many stores and flea markets still sell small turtles due to a loophole in the FDA regulation which allows turtles under 4 inches to be sold for educational purposes.

Some states have other laws and regulations regarding possession of red-eared sliders as pets because they are looked upon as invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....

 or pests where they are not native, but have been introduced through the pet trade. As of July 1, 2007, it is illegal in Florida to sell any wild type red-eared slider. Unusual color varieties such as albino and pastel red-eared sliders, which are derived from captive breeding, are still allowed for sale.

As food, traditional medicine, and cosmetics

The flesh of turtles was, and still is, considered a delicacy in a number of cultures. Turtle soup
Turtle soup
Turtle soup is soup or stews made from the flesh of the turtle. The dish exists in many cultures and is viewed as a luxury or delicacy.The green turtle was commonly used for turtle soup in the United States and United Kingdom. Soup made from the snapping turtle was found mainly in the United States...

 has been a prized dish in Anglo-American cuisine,
and still remains so in some parts of Asia. Gopher tortoise stew was popular with some groups in Florida.

Turtles remain a part of the traditional diet on the island of Grand Cayman
Grand Cayman
Grand Cayman is the largest of the three Cayman Islands and the location of the nation's capital, George Town. In relation to the other two Cayman Islands, it is approximately 75 miles southwest of Little Cayman and 90 miles southwest of Cayman Brac.-Geography:Grand Cayman encompasses 76% of...

, so much so that when wild stocks became depleted, a turtle farm
Turtle farming
Turtle farming is the practice of raising turtles and tortoises of various species commercially. Raised animals are sold for use as gourmet food, traditional medicine ingredients, or as pets...

 was established specifically to raise sea turtle
Sea turtle
Sea turtles are marine reptiles that inhabit all of the world's oceans except the Arctic.-Distribution:...

s for their meat. The farm also releases specimens to the wild as part of an effort to repopulate the Caribbean Sea.

Fat from turtles is also used in the Caribbean and in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 as a main ingredient in cosmetics, marketed under its Spanish name crema de tortuga.

Turtle plastrons (the part of the shell that covers a tortoise from the bottom) are widely used in traditional Chinese medicine
Traditional Chinese medicine
Traditional Chinese Medicine refers to a broad range of medicine practices sharing common theoretical concepts which have been developed in China and are based on a tradition of more than 2,000 years, including various forms of herbal medicine, acupuncture, massage , exercise , and dietary therapy...

; according to statistics, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

 imports hundreds of tons of plastrons every year. A popular medicinal preparation based on powdered turtle plastron (and a variety of herbs) is the guilinggao
Guilinggao
Guīlínggāo, also known as Tortoise Jelly or Turtle Jelly, is a jelly-like Chinese medicine, also sold as a dessert...

 jelly; these days, though, it is typically made with only herbal ingredients.

Conservation status

In February 2011, the IUCN/SSC Tortoise and Freshwater Turtle Specialist Group published a report about the top 25 species of turtles most likely to become extinct, with a further 40 species at very high risk of becoming extinct. This list excludes sea turtles, however both the leatherback and the Kemp's ridley
Kemp's Ridley
Kemp's ridley sea turtle , or Atlantic ridley sea turtle is the rarest sea turtle and is critically endangered. It is one of two living species in the genus Lepidochelys Kemp's ridley sea turtle (Lepidochelys kempii), or Atlantic ridley sea turtle is the rarest sea turtle and is critically...

 would make the top 25 list. The report is due to be updated in four years time allowing to follow the evolution of the list.
Between 48 to 54% of all 328 of their species considered threatened, turtles and tortoises are at a much higher risk of extinction than many other vertebrates. Of the 263 species of freshwater and terrestrial turtles, 117 species are considered Threatened, 73 are either Endangered or Critically Endangered and 1 is Extinct. Of the 58 species belonging to the Testudinidae family, 33 species are Threatened, 18 are either Endangered or Critically Endangered, 1 is Extinct in the wild and 7 species are Extinct. 71% of all tortoise species are either gone or almost gone.
Asian species are the most endangered, closely followed by the five endemic species from Madagascar. Turtles face many threats, including habitat destruction, harvesting for consumption and pet trade.
The high extinction risk for Asian species is primarily due to the long-term unsustainable exploitation of turtles and tortoises for consumption and traditional Chinese medicine, and to a lesser extent for the international pet trade.

Efforts have been made by Chinese entrepreneurs to satisfy increasing demand for turtle meat as gourmet food and traditional medicine with farmed turtles, instead of wild-caught ones; according to a study published in 2007, over a thousand turtle farms operated in China. Turtle farms in Oklahoma
Oklahoma
Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...

 and Louisiana
Louisiana
Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...

 raise turtles for export to China as well.

Nonetheless, wild turtles continue to be caught and sent to market in large number (as well as to turtle farms, to be used as breeding stock), resulting in a situation described by conservationists as "the Asian turtle crisis". In the words of the biologist George Amato, "the amount and the volume of captured turtles... vacuumed up entire species from areas in Southeast Asia", even as biologists still did not know how many distinct turtle species live in the region. About 75% of Asia's 90 tortoise and freshwater turtle species are estimated to have become threatened.

Harvesting wild turtles is legal in a number of states in the USA. In one of these states, Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

, just a single seafood company in Fort Lauderdale was reported in 2008 as buying about 5,000 pounds of softshell turtles a week. The harvesters (hunters) are paid about $2 a pound; some manage to catch as many as 30–40 turtles (500 pounds) on a good day. Some of the catch gets to the local restaurants, while most of it is exported to Asia. The Florida Fish and Wildlife Conservation Commission
Florida Fish and Wildlife Conservation Commission
The Florida Fish and Wildlife Conservation Commission is a Florida government agency charged with managing the state's fish and wildlife resources, regulating Florida's fisheries and wildlife, and enforcing related laws...

 estimated in 2008 that around 3,000 pounds of softshell turtles were exported each week via Tampa International Airport
Tampa International Airport
Tampa International Airport is a major public airport located six nautical miles west of the central business district of Tampa, in Hillsborough County, Florida, United States. This airport is publicly owned by Hillsborough County Aviation Authority...

.

Nonetheless, the great majority of turtles exported from the USA are farm raised. According to one estimate by the World Chelonian Trust, about 97% of 31.8 million animals harvested in the U.S. over a three-year period (November 4, 2002 – November 26, 2005) were exported. It has been estimated (presumably, over the same 2002–2005 period) that about 47% of the US turtle exports go to People's Republic of China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

 (predominantly to Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...

), another 20% to Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

, and 11% to Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

.

See also

  • Adwaita
    Adwaita
    Adwaita was the name of a male Aldabra giant tortoise in the Alipore Zoological Gardens of Kolkata, India...

    —a giant turtle that was reportedly 250 years old when it died in 2006
  • Araripemys arturi
    Araripemys arturi
    Araripemys is an extinct turtle genus, of which a fossil has been found in Brazil, supposed to be 120 million years old. According to the dating of this fossil, it therefore lived in the Early Cretaceous Period, the third period of the Mesozoic era....

  • Turtle racing
    Turtle racing
    Turtle racing is a popular event in which participants typically place turtles in the center of a circle and watch them walk around until one of them crosses out of the circle...



External links

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