Turtles are reptiles Reptiles, or members of the class Reptilia, are air-breathing, cold-blooded amniotes that have skin covered in scales or scutes as opposed to hair or feathers. They are tetrapods and lay amniote eggs, whose embryos are surrounded by the amnion membrane. Modern reptiles inhabit every continent with the exception of Antarctica, and four living of the order The Latin suffix -formes meaning "having the form of" is used for the scientific name of orders of birds and reptiles, but not for those of mammals and invertebrates Testudines (the crown group A crown group is the smallest monophyletic group, or "clade", to contain the last common ancestor of all extant members, and all of that ancestor's descendants. Extinct organisms can still be part of a crown group: for instance, the extinct dodo is still descended from the last common ancestor of all living birds, so falls within the of the superorder The Latin suffix -formes meaning "having the form of" is used for the scientific name of orders of birds and reptiles, but not for those of mammals and invertebrates Chelonia), characterised by a special bony Bones are rigid organs that form part of the endoskeleton of vertebrates. They function to move, 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. Because bones come in a variety of shapes and have a complex internal and external structure or cartilaginous Cartilage is a type of dense connective tissue. It is composed of specialized cells called chondrocytes that produce a large amount of extracellular matrix composed of collagen fibers, abundant ground substance rich in proteoglycan, and elastin fibers. Cartilage is classified in three types, elastic cartilage, hyaline cartilage and fibrocartilage, shell An exoskeleton is an external skeleton that supports and protects an animal's body, in contrast to the internal endoskeleton of, for example, a human. Some animals, such as the tortoise, have both an endoskeleton and an exoskeleton. In popular usage, many of the larger kinds of exoskeletons are known as "shells" developed from their ribs In vertebrate anatomy, ribs are the long curved bones which form the ribcage. In most vertebrates, ribs surround the chest (Greek:θώραξ, Latin thorax) and protect the lungs, heart, and other internal organs of the thorax. In some animals, especially snakes, ribs may provide support and protection for the entire body that acts as a shield A shield is a protective device, meant to intercept attacks. The term often refers to a device that is held in the hand/arm, as opposed to armour or a bullet proof vest. "Turtle" may either refer to the Testudines as a whole, or to particular Testudines which make up a form taxon In general taxonomy, it is a kind of wastebasket taxon, either a taxon that is not a natural group but united by shared plesiomorphies, or a presumably artificial group of organisms whose true relationships are not known, being obscured by ecomorphological similarity. Well-known form taxa of this kind include "ducks", "fish", & that is not monophyletic In common cladistic usage, a monophyletic group is a clade, consisting of an ancestor and all its descendants. The term is synonymous with the uncommon term holophyly—see also sea turtle The superfamily Chelonioidea has a worldwide distribution; sea turtles can be found in all oceans except for the polar regions.[citation needed] Some species travel between oceans. The Flatback turtle is found solely on the northern coast of Australia, terrapin The diamondback terrapin belongs to order Chelonia along with all other extant turtles. Malaclemys terrapin is the only member of the genus, and is closely related to large genus of North American map turtles, Graptemys. Malaclemys has been divided into seven different subspecies, but these divisions are generally not supported by molecular, tortoise Tortoises or land turtles are land-dwelling reptiles of the family of Testudinidae, order Testudines. Like their marine cousins, the sea turtles, tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The tortoise has both an endoskeleton, and the discussion below.

The order Testudines includes both extant (living) and extinct In biology and ecology, extinction is the death of a species or group of taxa. The moment of extinction is generally considered to be the death of the last individual of that species . Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena species. The earliest known turtles date from 215 million One million or one thousand thousand, is the natural number following 999,999 and preceding 1,000,001. The name is derived from Italian, where mille was 1,000, and 1,000,000 became milione, "a large thousand"[citation needed] years ago,[1] making turtles one of the oldest reptile groups and a more ancient group than lizards Lizards are a very large and widespread group of squamate reptiles, with nearly 5,000 species, ranging across all continents except Antarctica as well as most oceanic island chains. The group, traditionally recognized as the suborder Lacertilia, is defined as all extant members of the Lepidosauria which are neither sphenodonts (i.e., Tuatara) nor and snakes 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. Like lizards, from which they evolved, they have loosely articulated skulls and most can. About 300 species There are many definitions of what kind of unit a species is . A common definition is that of a group of organisms capable of interbreeding and producing fertile offspring, and separated from other such groups with which interbreeding does not (normally) happen. Other definitions may focus on similarity of DNA or morphology. Some species are are alive today, and some are highly endangered 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. An endangered species is usually a taxonomic species, but may be another evolutionary significant unit. The International Union for Conservation of Nature has.

Like other reptiles, turtles are ectotherms Ectothermic 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 temperature by basking in the sun. Many ectotherms are more specifically poikilothermic—varying their internal temperature according to the ambient environment, commonly called cold-blooded. Like other amniotes The amniotes are a group of tetrapod vertebrates that have a terrestrially adapted egg. They include mammals, birds and reptiles, 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. In humans, these membranes include the amniotic sac that (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.

Contents

Anatomy and morphology

Chelonia mydas in Kona, Hawaii The State of Hawaii ( /həˈwaɪ.iː/ or /həˈwaɪʔiː/ in English; Hawaiian: Mokuʻāina o Hawaiʻi) is a state in the United States, located on an archipelago in the central Pacific Ocean southwest of the continental United States, southeast of Japan, and northeast of Australia. The state was admitted to the Union on August 21, 1959, making it

The largest chelonian is the great leatherback sea turtle The leatherback 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 carapace is covered by skin and oily flesh. Dermochelys, which reaches a shell length of 200 centimetres (6.6 ft) and can reach a weight of over 900 kilograms (2,000 lb). Freshwater turtles are generally smaller, but with the largest species, the Asian softshell turtle Pelochelys cantorii, a few individuals have been reported up to 200 centimetres (6.6 ft). This dwarfs even the better-known Alligator Snapping Turtle The Alligator Snapping Turtle is one of the largest freshwater turtles in the world. It is a larger and less aggressive relative of the Common Snapping Turtle. The epithet temminckii is in honor of Dutch zoologist Coenraad Jacob Temminck, the largest chelonian in North America, which attains a shell length of up to 80 centimetres (2.6 ft) and a weight of about 60 kilograms (130 lb). Giant tortoises of the genera Geochelone, Meiolania, 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 that humans hunted them for food. The only surviving giant tortoises Giant tortoises are characteristic reptiles of certain tropical islands. They occur in such places as Madagascar, the Seychelles, Mauritius, Réunion, the Galápagos Islands, Sulawesi, Timor, Flores and Java, 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. However, giant tortoises are on the Seychelles Seychelles , officially the Republic of Seychelles (French: République des Seychelles; Creole: Repiblik Sesel), is an archipelago nation of 115 islands in the Indian Ocean, some 1,500 kilometres (930 mi) east of mainland Africa, northeast of the island of Madagascar. Other nearby island countries and territories include Zanzibar to the west, and Galápagos Islands Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, 972 km west of continental Ecuador. It is a UNESCO World Heritage site: wildlife is its most notable feature and can grow to over 130 centimetres (51 in) in length, and weigh about 300 kilograms (660 lb).[2]

The largest ever chelonian was Archelon ischyros, a Late Cretaceous The Cretaceous , usually abbreviated K for its German translation Kreide, is a geologic period and system from circa 145.5 ± 4 to 65.5 ± 0.3 million years ago (Ma). In the geologic timescale, the Cretaceous follows on the Jurassic period and is followed by the Paleogene period. It is the youngest period of the Mesozoic era, and at 80 million sea turtle known to have been up to 4.6 metres (15 ft) long.[3]

The smallest turtle is the Speckled Padloper Tortoise 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 turtles and musk turtles that live in an area that ranges from Canada Canada is a country occupying most of upper North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean. It is the world's second largest country by total area and shares the world's longest common border with the United States to the south and northwest to South America South America is the southern continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean; North America and the Caribbean Sea lie to the. The shell length of many species in this group is less than 13 centimetres (5.1 in) in length.

A turtle with eyes closer to the end of the head. Keeping only the nostrils and the eyes above the water surface. African Spurred Tortoise in the zoo of Sharm el-Sheikh Sharm el Sheikh , is a city situated on the southern tip of the Sinai Peninsula, in South Sinai Governorate, Egypt, on the coastal strip between the Red Sea and Mount Sinai Turtle at a zoo in the Czech republic The Czech Republic /ˈtʃɛk rɨˈpʌblɪk/ (Czech: Česká republika, pronounced [ˈtʃɛskaː ˈrɛpuˌblɪka] ( listen), short form Česko [ˈtʃɛskɔ]) is a landlocked country in Central Europe. The country borders Poland to the northeast, Germany to the west and northwest, Austria to the south and Slovakia to the east. The capital and

Neck folding

Turtles are broken down into two groups, according to how they evolved a solution to the problem of withdrawing their neck into their shell (something the ancestral Proganochelys Proganochelys quenstedtii 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. It has several synonyms, including Chelytherium , Psammochelys ("Sand Turtle"), Stegochelys ("Roof Turtle") and could not do): the Cryptodira, which can draw their neck in while contracting it under their spine; and the Pleurodira, which contract their neck to the side.

Head

Most turtles that spend most of their life 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 is a dietary mineral composed primarily of sodium chloride that is essential for animal life, but toxic to most land plants. Salt flavor is one of the basic tastes, an important preservative and a popular food seasoning taken in from the water they drink.

Turtles are thought to have exceptional night vision due to the unusually large number of rod cells 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 photoreceptor, cone cells. Because they are more light sensitive, rods are responsible for night vision. Named for their cylindrical shape, rods are concentrated at the outer edges of the retina and are used in 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 Pursuit movement is the ability of the eyes to smoothly follow a moving object. It is one of two ways that visual animals can voluntarily shift gaze, the other being saccadic eye movements. Pursuit differs from the vestibulo-ocular reflex, which only occurs during movements of the head and serves to stabilize gaze on a stationary object. Most 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 jaws In arthropods, the jaws are chitinous and oppose laterally, and may consist of mandibles, chelicerae, or loosely, pedipalps 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 A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids as well as vertebrates such as chelonians, order Testudines, turtles and tortoises. The lower shell that encases the belly is called the plastron The plastron is the nearly flat part of the shell structure of a turtle or tortoise, what one would call the belly, similar in composition to the carapace; with an external layer of horny material divided into plates called scutes and an underlying layer of interlocking bones. 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 includes 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 scutes that are part of its outer skin, or epidermis The epidermis is composed of 4-5 layers depending on the region of skin being considered. Those layers in descending order are the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. The term Malpighian layer refers to both the basal and spinosum layers. Scutes are made up of a fibrous protein Proteins are organic compounds made of amino acids arranged in a linear chain. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In called keratin Keratins are a family of fibrous structural proteins; tough and insoluble, they form the hard but mineralized structures found in reptiles, birds, amphibians, and mammals. They are rivaled as biological materials in toughness only by chitin 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 that 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, 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 the 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 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 There are two extant species of the family Chelydridae: Chelydra serpentina, the Common Snapping Turtle, and its larger relative Macrochelys temminckii, the Alligator Snapping Turtle . Both are endemic to the Western Hemisphere and musk turtles 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 is a reptile that is common in southern Canada, the United States, and northern Mexico and is related to other water turtles such as sliders and cooters. This turtle lives in ponds, lakes, marshes, and in slow-moving rivers that have soft, muddy bottoms. The maximum carapace size, or shell length, for painted turtles is 10 inches (25 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 fontanelles A fontanelle is an anatomical feature on an infant's skull. 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 cause the fontanelles to close over by a child's second birthday. The between the shell bones. The shell of a leatherback turtle is extremely light because they lack scutes and contain many fontanelles.

Skin and molting

Snapping Turtle Tail. Blue Hills Reservation, Massachusetts

As mentioned above, the outer layer of the shell is part of the skin, each scute (or plate) on the shell corresponding 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 and terrapins do not molt their skins all in one go, 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 you know how many scutes are produced in a year.[4] 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 that the feet are webbed and often have long claws A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end of the leg or tarsus for gripping a surface as the creature walks. However, the word "claws" is most often used in. These turtles swim using all four feet in a way similar to the dog paddle It was the first swimming stroke used by ancient man, believed to have been learned by observing animals swim. Prehistoric cave paintings in Egypt show figures doing what appears to be the doggy 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 also have very long claws, used to help them clamber onto riverbanks and floating logs, upon which they like to bask. 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 A flipper is typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example most fish , as well as certain mammals (cetaceans, pinnipeds), reptiles (turtles, and the now extinct plesiosaurs, mosasaurs, ichthyosaurs, and metriorhynchids), and birds (penguins) 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 rudders A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft,or other conveyance that moves through a fluid . 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. A rudder operates by redirecting the fluid past the hull or fuselage, thus 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 cloacal 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 from the water using these papillae, in much the same way that fish use gills to respire.

Turtles lay eggs, 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 than 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: 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.[5]

Systematics and evolution

Main article: List of Testudines families "Chelonia" (Testudines) from Ernst Haeckel's Kunstformen der Natur, 1904

The first proto-turtles are believed to have existed in the early Triassic Period of the Mesozoic era, about 220 million years ago, and their shell, which has remained a remarkably stable 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, the "half-shelled turtle with teeth", have been found near Guangling in south-west China, which displays a complete bony plastron and an incomplete carapace, similar to an early stage of turtle embryonic development.[6] Prior to this discovery, the earliest fossil turtles were terrestrial and had a complete shell, offering no clue to the evolution of this remarkable anatomical feature. By the late Jurassic, turtles had radiated widely, and their fossil history becomes easier to read.

Their exact ancestry is disputed. It was believed that they are the only surviving branch of the ancient clade Anapsida, which includes groups such as procolophonids, millerettids, protorothyrids, and pareiasaurs. All anapsid skulls lack a temporal opening, while all other extant amniotes have temporal openings (although in mammals the hole has become the zygomatic arch). The millerettids, protorothyrids, and pareiasaurs became extinct in the late Permian period, and the procolophonoids during the Triassic.[7]

However, it was recently suggested that the anapsid-like turtle skull may be due to reversion rather than to anapsid descent. More recent morphological phylogenetic studies with this in mind placed turtles firmly within diapsids, slightly closer to Squamata than to Archosauria.[8] All molecular studies have strongly upheld the placement of turtles within diapsids, though some place turtles closer to Archosauria than Squamata.[9] Reanalysis of prior phylogenies suggests that 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. As of 2003, the consensus is that Testudines diverged from other diapsids between 200 and 279 million years ago.[10]

The earliest known fully-shelled turtle is the late-Triassic Proganochelys, though this 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, implying an ancestry occupying a similar niche to the ankylosaurs (though only through parallel evolution).

Turtles are divided into three suborders, one of which, the Paracryptodira, is extinct. The two extant suborders are the Cryptodira and the Pleurodira. 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.

Basal and incertae sedis chelonians

Suborder †Proganochelydia

Fossil of Proganochelys quenstedti, one of the oldest true turtles presently known. Unlike modern Testudines, Proganochelys was not able to hide its head under the shell.

Suborder Cryptodira

Basal genera

Infraorder †Paracryptodira

Infraorder Eucryptodira

The African Helmeted Turtle (Pelomedusa subrufa) is a pleurodire. Pleurodires hide their head sideways.

Suborder Pleurodira

Turtle, tortoise, or terrapin?

Different animals are called turtles, tortoises, or terrapins in different varieties of English

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.

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 word χελώνη (chelone, modern Greek χελώνα), meaning tortoise.

As pets

Wikibooks has a book on the topic of Keeping Pet Turtles

Turtles, particularly small terrestrial and freshwater turtles, are commonly kept as pets. Among the most popular are Russian Tortoises, Spur-thighed Tortoises, and Red-eared sliders (or Red-eared terrapin).[12]

In the United States, due to the ease of contracting salmonella 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 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. [13][14]

Some states have other laws and regulations regarding possession of Red-eared Sliders (abbreviated as RES) as pets because they are looked upon as invasive species 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 RES. Unusual color varieties such as albino and pastel RES, which are derived from captive breeding, are still allowed for sale. [15]

As food

The window of a restaurant serving guilinggao, decorated with a 龜 ('turtle') character

The flesh of turtles was, and still is, considered a delicacy in a number of cultures. Turtle soup has been a prized dish in Anglo-American cuisine, and still remains so in some parts of the Far East.

Guilinggao jelly was a Chinese medicine preparation containing powdered shell of a certain turtle species; these days, though, it is typically made with only herbal ingredients.

Harvesting wild turtles is legal in Florida, and a single seafood company in Fort Lauderdale was reported (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 the Far East; Florida Fish and Wildlife Conservation Commission estimates (2008) that around 3,000 pounds of softshell turtles are exported each week via Tampa International Airport.[16]

Gallery

Closeup head-on view of a common snapping turtle (Chelydra serpentina), taken near the St. Lawrence River in northern New York State

Turtle in the backyard of a Florida Resident.

In culture

Main article: Cultural depictions of turtles and tortoises

See also

Further reading

References

  1. ^ "Archelon-Enchanted Learning Software". Enchantedlearning.com. http://www.enchantedlearning.com/subjects/dinosaurs/dinos/Archelon.shtml. Retrieved on 2009-03-14.
  2. ^ Michael J. Connor. "CTTC's Turtle Trivia". Tortoise.org. http://www.tortoise.org/general/wildfaqs.html#largest. Retrieved on 2009-03-14.
  3. ^ "Marine Turtles". Oceansofkansas.com. http://www.oceansofkansas.com/Turtles.html. Retrieved on 2009-03-14.
  4. ^ "Anatomy and Diseases of the Shells of Turtles and Tortoises". Peteducation.com. http://www.peteducation.com/article.cfm?articleid=2700. Retrieved on 2009-03-14.
  5. ^ All but Ageless, Turtles Face Their Biggest Threat: Humans
  6. ^ Li C, Wu XC, Rieppel O, Wang LT, Zhao LJ (November 2008). "An ancestral turtle from the Late Triassic of southwestern China". Nature 456 (7221): 497–501. doi:10.1038/nature07533. PMID 19037315.
  7. ^ "Introduction to Procolophonoidea". Ucmp.berkeley.edu. http://www.ucmp.berkeley.edu/anapsids/procolophonoidea.html. Retrieved on 2009-03-14.
  8. ^ Rieppel O, DeBraga M (1996). "Turtles as diapsid reptiles". Nature 384: 453–5. doi:10.1038/384453a0.
  9. ^ Zardoya R, Meyer A (November 1998). "Complete mitochondrial genome suggests diapsid affinities of turtles". Proc. Natl. Acad. Sci. U.S.A. 95 (24): 14226–31. doi:10.1073/pnas.95.24.14226. PMID 9826682. PMC: 24355. http://www.pnas.org/cgi/pmidlookup?view=long&pmid=9826682.
  10. ^ McGeoch DJ, Gatherer D (January 2005). "Integrating reptilian herpesviruses into the family herpesviridae". J. Virol. 79 (2): 725–31. doi:10.1128/JVI.79.2.725-731.2005. PMID 15613300.
  11. ^ http://www.bartleby.com/61/1/T0120100.html
  12. ^ David Alderton (1986). An Interpret Guide to Reptiles & Amphibians, Salamander Books Ltd., London & New York.
  13. ^ GCTTS FAQ: "4 Inch Law", actually an FDA regulation
  14. ^ Turtles intrastate and interstate requirements; FDA Regulation, Sec. 1240.62, page 678 part d1.
  15. ^ Turtle ban begins today; New state law, newszap.com, 2007-07-01. Retrieved 2007-07-06.
  16. ^ "China Gobbling Up Florida Turtles", By Craig Pittman, St. Petersburg Times. Published: Thursday, October 9, 2008

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Categories: Turtles | Testudinidae

 

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'Turtle' News
Rehabilitated sea turtle - WAVY-TV
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Rehabilitated sea turtle

WAVY-TV

"Kermit," a green sea turtle rehabilitated after being found on the beach with trash lodged in his throat, was released back to his natural habitat Monday ...

Stranded sea turtle released in Sandbridge WVEC.com (subscription)



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Frugal and Fabulous: Giveaway: Turtle Chex Mix Bars!

(Lindsay)

Fri, 03 Jul 2009 14:00:00 GM

Have you heard of Chex Mixes New . Turtle. Bars? Oh.My.Goodness!​ If you like cereal bars you are in for a treat! These bars are made of caramel covered Corn Chex and Wheat Chex with chocolate, peanuts and pretzels mixed in! Yum! ...

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'Turtle' Answers
How can I tell if my turtle has somanilla shedding?
Q. Theres white stuff that keeps showing up in the tank and i was reading that turtles can carry diseases... I'm a little worried that it might. I mean it might not. Also how do you tell if a turtle is a male or female?
Asked by twiztedtinx - Fri May 16 10:13:38 2008 - - 2 Answers - 0 Comments

A. Salmonella is too small to see. Assume that your turtle has it and wash your hands after touching it or its water. The white stuff might be fungus or it might be any one of a number of different types of crud. When your turtle is old enough, look at its tail from underneath. Find the vent. If it is under the rim of the upper shell, you have either a female or an immature male. If it is beyond the rim, you have a mature male.
Answered by oikos - Sat May 17 12:04:40 2008

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