Health and Illnesses in Pet Turtles Pets4Homes

Health and Illnesses in Pet Turtles Pets4Homes

Turtles are diapsids of the particular order Testudines (or Chelonii) seen as a a special bony or cartilaginous shell created from their ribs plus acting as a shield. "Turtle" may refer in order to the order as the whole (American English) or even to fresh-water and sea-dwelling testudines (British English). The particular order Testudines includes both extant (living) and wiped out species. The earliest identified members of this team date from 220 mil years ago, making turtles one of the earliest reptile groups and a more ancient group than snakes or crocodilians. Associated with the 356 known species alive today, some are usually highly endangered.

Turtles are ectotherms—animals commonly called cold-blooded—meaning that their internal heat varies according to the ambient environment. However, because of their high metabolic rate, leatherback sea turtles have a body temp that is noticeably increased than that of the particular surrounding water. Turtles are usually classified as amniotes, together with other reptiles, wild birds, and mammals. Like other amniotes, turtles breathe air and do not lay down eggs underwater, although several species live in or around water. The study of turtles is known as cheloniology, after the Greek word for turtle. It is usually also sometimes called testudinology, after the Latin title for turtles.

Differences can be found in usage of the particular common terms turtle, tortoise, and terrapin, according to the range of English being utilized. These terms are common names and don't reflect exact biological or taxonomic variations.

Turtle may either refer to the order as a whole, or to particular turtles that create up a form taxon which is not monophyletic, or might be restricted to only marine species. Tortoise usually refers to any land-dwelling, non-swimming chelonian. Terrapin can be used in order to describe several species of small, edible, hard-shell turtles, typically those found in brackish waters.

In Northern America, all chelonians are commonly called turtles. Tortoise is used only in reference to fully terrestrial turtles or, more narrowly, only those members of Testudinidae, your family of modern land tortoises. Terrapin may refer to small semi-aquatic turtles that live in refreshing and brackish water, particularly the diamondback terrapin (Malaclemys terrapin). Although the users of the genus Terrapene dwell mostly on land, these people are known as box turtles rather than tortoises. The American Society of Ichthyologists and Herpetologists uses "turtle" to describe all species of the order Testudines, whether or not they are land-dwelling or even sea-dwelling, and uses "tortoise" like a more specific expression for slow-moving terrestrial varieties.

In the United Empire, the word turtle is used for water-dwelling species, including ones known in the US as terrapins, but not for terrestrial species, which are known only as tortoises.

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Eastern Box Turtle Info Turtle

The word chelonian is usually popular among veterinarians, scientists, plus conservationists working with these animals being a catch-all name for any member of the particular superorder Chelonia, including just about all turtles living and extinct, as well as their immediate ancestors. Chelonia is usually based on the Ancient greek word for turtles, χελώνη chelone; Greek χέλυς chelys "tortoise" is also used in the formation of scientific names of chelonians. Testudines, on the other hands, is based on the particular Latin word for tortoise, testudo. Terrapin comes from an Algonquian word regarding turtle.

Some languages perform not have this variation, as all of these are known by the same name. For instance , within Spanish, the word tortuga is used for turtles, tortoises, and terrapins. The sea-dwelling turtle is tortuga marina, a freshwater species tortuga de río, plus a tortoise tortuga terrestre.

The largest living chelonian is the leatherback ocean turtle (Dermochelys coriacea), which usually reaches a shell duration of 200 cm (6. six ft) and can reach a weight of more than 900 kg (2, 500 lb). Freshwater turtles are usually generally smaller, but along with the largest species, the particular Asian softshell turtle Pelochelys cantorii, a few people have been reported up to 200 cm (6. 6 ft). This dwarfs even the better-known alligator snapping turtle, the biggest chelonian in North The united states, which attains a covering length of up to 80 cm (2. six ft) and weighs as much as 113. 4 kg (250 lb).

Large tortoises of the genera Geochelone, Meiolania, and others were relatively widely distributed all over the world into prehistoric times, and they are known to have existed in North and South America, Australia, and Africa. They became vanished at the same time as the appearance associated with man, and it is usually assumed humans hunted them for food. The just surviving giant tortoises are on the Seychelles and Galápagos Islands and may develop to over 130 cm (51 in) in length, and weigh about 300 kg (660 lb).

The particular largest ever chelonian has been Archelon ischyros, a Late Cretaceous sea turtle identified to have been up to 4. 6 m (15 ft) long.

Black marsh turtle Wikipedia

The smallest turtle is the speckled padloper tortoise of South Africa. It measures no more than 8 cm (3. 1 in) in length and weighs about 140 g (4. 9 oz). Two other species of small turtles are the particular American mud turtles and musk turtles that live in an area that ranges from Canada to South America. The shell length of many species within this group is less than 13 cm (5. 1 in) long.

Turtles are divided into 2 groups, according to how they retract their necks into their shells (something the ancestral Proganochelys could not do). The mechanism of throat retraction differs phylogenetically: the particular suborder Pleurodira retracts side to side aside, anterior to make girdles, while the suborder Cryptodira retracts straight back again, between shoulder girdles. These types of motions are largely because of to the morphology and arrangement of cervical backbone. Of all recent turtles, the cervical column is made up of nine joints plus eight vertebrae, which are individually independent. Since these vertebrae are not joined and are rounded, the neck is more versatile, being able to bend in the backwards and sideways directions. The major function and evolutionary implication of neck retraction will be thought to be for feeding rather than security. Neck retraction and reciprocal extension allows the turtle to reach out further in order to capture prey while going swimming. Neck expansion creates suction once the head is thrust forward and the oropharynx is expanded, and this particular morphology suggests the retraction function is for feeding purposes as the suction helps catch prey. The particular protection the shell offers the head when it is retracted is therefore not the main function of retraction, thus is an exaptation. As with regard to the difference between the two methods of retraction, both Pleurodirans and Cryptodirans use the quick expansion of the neck as a method of predation, so the difference in retraction mechanism is not due in order to a difference in environmental niche.

Head

Most turtles that spend most of their lives on land get their eyes looking straight down at objects in front side of them. Some marine turtles, such as nipping turtles and soft-shelled turtles, have eyes closer in order to the top of the mind. These types of turtle can hide from predators within shallow water, where they will lie entirely submerged except for their eyes and nostrils. Near their eyes, sea turtles possess glands that produce salty tears that rid themselves of excess salt taken in from the water they consume.

Turtles have rigid beaks and use their jaws to cut and chew food. Instead of getting teeth, that they appear in order to have lost about 150-200 million years ago, the upper and lower jaws of the turtle are covered by horny side rails. Carnivorous turtles usually have got knife-sharp ridges for cutting through their prey. Herbivorous turtles have serrated-edged side rails that help them cut through tough plants. They will use their tongues in order to swallow food, but as opposed to most reptiles, they can not stay out their tongues to catch food.

ShellMajor article: Turtle shellTop of the shell of the turtle is known as the carapace. The particular lower shell that encases the belly is known as 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 upward of about 60 bone fragments that include portions associated with the backbone and the ribs, meaning the turtle cannot crawl away from its shell. In most turtles, the outer layer from the shell is covered simply by horny scales called scutes which are part of its outer skin, or epidermis. Scutes comprise of the particular fibrous protein keratin that will also makes up the scales of other reptiles. These scutes overlap the seams between the covering bones and add strength towards the shell. Some turtles do not possess horny scutes; regarding example, the leatherback ocean turtle and the soft-shelled turtles have shells covered with leathery skin instead.

The shape of the cover gives helpful clues about how exactly a turtle lives. Many tortoises have a big, dome-shaped shell that can make it difficult for predators to crush the shell between their jaws. A single of the few exclusions is the African hot cake tortoise, which has the flat, flexible shell that will allows it to hide in rock crevices. Most aquatic turtles have toned, streamlined shells, which aid in swimming and diving. American snapping turtles and musk turtles have small, cross-shaped plastrons that give all of them more efficient leg motion for walking along the particular bottom of ponds and streams. Another exception is usually the Belawan Turtle (Cirebon, West Java), which has sunken-back soft-shell.

The color of the turtle's shell may vary. Shells are commonly colored brown, black, or olive green. In some species, covers may have red, lemon, yellow, or grey markings, often spots, lines, or even irregular blotches. Probably the most colourful turtles is the eastern painted turtle, which contains a yellow plastron and a black or olive shell with red markings around the rim.

Tortoises, being land-based, have rather heavy shells. In comparison, aquatic and soft-shelled turtles have lighter shells that help them avoid going in water and go swimming faster with more agility. These lighter shells have large spaces called fontanelles between the shell our bones. The shells of leatherback sea turtles are incredibly lighting because they lack scutes and contain many fontanelles.

It has been recommended by Jackson (2002) that the turtle shell can function as pH barrier. To endure through anoxic conditions, such as wintertime periods trapped beneath glaciers or within anoxic mud at the end of ponds, turtles utilize two general physiological mechanisms. In the case of prolonged periods of anoxia, it has been shown that the turtle covering both releases carbonate buffers and uptakes lactic acid.

turtles The Wild World of Zoobooks

Respiration Turtles

Respiration, for many amniotes, is achieved by the particular contraction and relaxation of specific muscles (i. e. intercostals, abs, and/or a diaphragm) attached with an inner rib-cage that can expand or contract the entire body wall thus assisting airflow out and in of the lungs. The ribs of Chelonians, however, are fused with their carapace and exterior to their pelvic plus pectoral girdles, a function unique among turtles. This rigid shell is not capable of expansion, plus by rendering their rib-cage immobile, Testudines have experienced to evolve special adaptations for respiration.

Turtle pulmonary ventilation occurs by making use of specific groups of abdominal muscle tissue attached to their viscera and shell that draw the lungs ventrally during inspiration, where air is usually drawn in via a negative pressure gradient (Boyle's Law). In expiration, the particular contraction from the transversus abdominis is the driving push by propelling the viscera into the lungs and expelling air under optimistic pressure. Conversely, the calming and flattening of the particular oblique abdominis muscle pulls the transversus back straight down which, once again, draws air flow back into the lungs. Important auxiliary muscles utilized for ventilatory processes are the pectoralis, which is used in conjunction with the transverse abdominis during inspiration, as well as the serratus, which moves with all the abdominal oblique associated expiration.

The lungs of Testudines are multi-chambered plus attached their entire length down the carapace. The number of chambers can vary between taxa, though most commonly they have three lateral compartments, three medial chambers, and another terminal chamber. As previously mentioned, the act of specific abdominal muscles pulling straight down the viscera (or pushing back up) is exactly what allows for respiration in turtles. Specifically, it is usually the turtles large liver organ that pulls or pushes on the lungs. Ventral to the lungs, in the coelomic cavity, the liver of turtles is attached directly to the correct lung, and their abdomen is directly attached in order to the left lung simply by the ventral mesopneumonium, which is attached to their liver by the ventral mesentery. When the liver is drawn down, inspiration begins. Assisting the lungs is the post-pulmonary septum, that is discovered in all Testudines, and is thought to prevent the particular lungs from collapsing.

Marine turtles characteristics, key to the 7 marine species, ecology, habitat and range, behavior

Turtles Skin and molting

As described above, the outer coating of the shell will be part of the pores and skin; each scute (or plate) on the shell refers to a single modified scale. The remainder associated with the skin has a lot smaller scales, similar to the pores and skin of other reptiles. Turtles do not molt their skins all at once as snakes do, but continuously in small items. When turtles are held in aquaria, small sheets of dead skin can be seen in the water (often appearing to be a thin item of plastic) having already been sloughed off when the particular animals deliberately rub by themselves against a piece of wood or even stone. Tortoises also shed skin, but 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 created by the stack associated with smaller, older scutes along with the larger, newer ones, you are able to estimate the age of a turtle, when one knows how many scutes are produced in per year. This method is not very accurate, partly because growth rate is not constant, but also since some of the scutes eventually fall away from the shell.

Turtles Limbs

Terrestrial tortoises have short, sturdy feet. Tortoises are well-known for moving slowly, simply because of their weighty, cumbersome shells, which limit stride length.

Skeleton of snapping turtle (Chelydra serpentina)

Amphibious turtles normally have got limbs similar to those of tortoises, except that the particular feet are webbed plus often have long claws. These turtles swim using all four feet in a way similar in order to the dog paddle, with the feet on the particular left and right side of the body alternately providing drive. Large turtles tend to swim less than smaller ones, and the very big species, such because alligator snapping turtles, hardly swim at all, preferring in order to walk across the bottom associated with the river or lake. As well as webbed feet, turtles have extremely long claws, used to help them clamber onto riverbanks and floating records upon which they bask. Male turtles tend to have particularly long claws, and these look like used to stimulate the woman while mating. While most turtles have webbed foot, some, such as the pig-nosed turtle, have true flippers, with the digits being fused into paddles as well as the paws being relatively small. These types of species swim in the same way because sea turtles do (see below).

Sea turtles are usually almost entirely aquatic plus have flippers instead associated with feet. Sea turtles travel through the water, using the up-and-down motion of the particular front flippers to generate drive; the back feet aren't used for propulsion yet can be utilized as rudders with regard to steering. Compared with freshwater turtles, sea turtles have very limited mobility on land, and in addition to the dash from the nest to the sea as hatchlings, man sea turtles normally never leave the sea. Women must come back onto land to lay eggs. They move very slowly and laboriously, dragging themselves forwards with their flippers.

Habits of Turtles

Senses of Turtles are thought to have exceptional night vision because of the unusually large amount of rod cells in their retinas. Turtles have got color vision with a wealth of cone subtypes with sensitivities ranging through the near ultraviolet (UVA) to red. Some property turtles have very bad pursuit movement abilities, which usually are normally found only in predators that search quick-moving prey, but carnivorous turtles are able in order to move their heads quickly to snap.

Turtles Communication

The Arrau turtle has a sizable vocal repertoire.

While typically thought of because mute, turtles make different sounds when communicating. Tortoises might be vocal when dating and mating. Various species of both freshwater plus sea turtles emit numerous types of calls, usually short and low frequency, from the time they are in the egg to when they are adults. These types of vocalizations may serve in order to create group cohesion when migrating.

Turtle Intelligence

See also: Animal knowledge

It offers been reported that wood turtles are better compared to white rats at understanding to navigate mazes. Situation studies exist of turtles playing. They are doing, however, possess a very low encephalization quotient (relative brain in order to body mass), and their particular hard shells enable them to live without fast reflexes or elaborate predator prevention strategies. In the laboratory, turtles (Pseudemys nelsoni) may learn novel operant jobs and have demonstrated a long lasting memory of at least 7. 5 months.

Turtle Mating Strategies

An instance of mounting behavior in turtles

Turtles are known for displaying a wide variety of mating actions, however , they are not known for forming pair-bonds or for being component of a social team. Once fertilization has occurred and an offspring offers been produced, neither parent will provide care with regard to the offspring once it can hatched. Females generally outnumber males in various turtle species (such as Eco-friendly turtles), and thus, most males will participate in multiple copulation with multiple partners throughout their lifespan. However, due to the sexual dimorphism present in most turtle species, males must develop different courting strategies or use alternate methods to gain access to a potential mate. Most terrestrial varieties have males that are larger than females, and fighting between males often establishes a hierarchical order in which the higher upward the order an person is, the better the particular chance is of the person getting access to the potential mate. For the majority of semi-aquatic species and bottom-walking aquatic species, combat happens less often. Males that belong to semi-aquatic and bottom-walking species instead often make use of their larger size advantage to forcibly mate having a female. In fully aquatic species, males are frequently smaller than females plus therefore they cannot use the same strategy as their semi-aquatic relatives, which relies on overwhelming the females with strength. Males in this group resort to using courtship displays in an try to gain mating access to a female.

Combating Between Males Turtles

Saddle back again Galapagos tortoise

Wood turtles is surely an example of the terrestrial species where the particular males have a hierarchical ranking system based upon dominance through fighting, and it's shown that the males with the greatest rank and thus the most wins in battles have the most children.

Galapagos tortoises are one more example of a varieties which has a hierarchical rank that is determined by dominance displays, and entry to food and partners is regulated by this dominance hierarchy. Two man saddle backs most usually compete for access to cactus trees, that is their source of food. The winner is the individual who stretches their neck of the guitar the highest, which individual gets access to the cactus tree, which may attract potential mates.

Pressure Mating Turtles

Male (left) plus female (right) radiated tortoise

The male scorpion mud turtle is an example of a bottom-walking marine species that relies on overpowering females with its larger size as a mating strategy. The male techniques the female from the back, and often resorts to aggressive methods like gnawing at the female's tail or hind limbs, followed by a mounting behavior in which usually the male clasps the particular edges of her carapace with his forelimbs and hind limbs to keep her in position. The man follows this action by laterally waving his mind and sometimes biting the female's head in a good attempt to get the girl to withdraw her go to her shell. This reveals her cloaca, and with it exposed, the man can attempt copulation by seeking to insert his grasping tail.

Male radiated tortoises may also be known to use the force mating strategy wherein they use encircling vegetation to trap or even prevent females from escaping, then pin them down for copulation.

Turtles Courtship Shows

Red-eared sliders are a good example of a fully aquatic species where the male performs a courtship behavior. Within this case the male extends his forelegs using the palms facing out and flutters his forelegs within the female's face. Female options are important in this technique, and the females of some species, such as green sea turtles, aren't usually receptive. As a result, they've progressed certain behaviors to prevent the male's attempts at copulation, such as swimming away, confronting the male followed by biting, or even a refusal position in which the female presumes a vertical position with her limbs widely outspread and her plastron dealing with the male. If the water is too superficial to perform the refusal position, the females will resort to beaching by themselves, which is a verified deterrent method, as the males is not going to follow them ashore.

Ecology and life history of turtles

Sea turtle swimming

Although several turtles spend large quantities of their lives marine, all turtles and tortoises breathe air and must surface at regular periods to refill their lungs. They can also spend much or all of their lives on dry land. Aquatic respiration within Australian freshwater turtles is usually currently being studied. A few species have large cloacal cavities that are lined numerous finger-like projections. These projections, called papillae, possess a rich blood provide and raise the surface area of the cloaca. The particular turtles can take upward dissolved oxygen from the water providing a few papillae, in much the same method that fish use gills to respire.

Like some other reptiles, turtles lay eggs that are slightly gentle and leathery. The eggs from the greatest species are usually spherical while the ovum of the rest are elongated. Their albumen will be white and contains an alternative protein from bird eggs, such that it will not coagulate when cooked. Turtle eggs ready to eat consist mainly of yolk. In some species, heat determines whether an egg develops into a male or even a female: a higher temperature causes a female, the lower temperature causes a male. Large numbers of ovum are deposited in openings dug into mud or sand. They are then covered and left to incubate by themselves. Depending upon the species, the eggs will typically take 70–120 days to hatch. When the turtles hatch, they squirm their way to the surface and head toward the water. There are no known species in which the mom cares for her youthful.

Sea turtles lay their particular eggs on dry, sandy beaches. Immature sea turtles are not cared regarding 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 lately discovered a turtle's organs tend not to steadily break down or become less efficient over time, unlike the majority of other animals. It was found that the liver, lungs, and kidneys of a centenarian turtle are usually virtually indistinguishable from those of its immature equal. This has inspired genetic researchers to start evaluating the turtle genome regarding longevity genes.

A group of turtles is known as a bale.

Turtles Diet

A green sea turtle grazing on

A turtle's diet differs greatly determined by the atmosphere by which it lives. Mature turtles typically eat marine plants; (citation needed) invertebrates such as insects, snails, and worms; and have been reported to occasionally consume dead marine animals. Several small freshwater species are carnivorous, eating small fish and an array of aquatic life. However, protein is important to turtle growth plus juvenile turtles are purely carnivorous.

Sea turtles generally feed on jellyfish, sponges, and other soft-bodied organisms. Some species with better jaws have been observed to eat shellfish, while others, such as the green sea turtle, do not eat meat at all plus, instead, have a diet largely made up of algae.

Systematics and evolution of Turtles

Primary article: Turtle classification

See|Observe|Notice} also: List of Testudines family members

Life restoration associated with Odontochelys semitestacea, the oldest known turtle relative along with a partial shell

"Chelonia" from Ernst Haeckel's Kunstformen der Natur, 1904

Dependent on body fossils, the first proto-turtles are believed to have existed in the particular late Triassic Period of the Mesozoic era, about 220 million years ago, and their shell, which has remained a remarkably stable body plan, will be thought to have evolved through bony extensions of their backbones and broad steak that expanded and increased together to form a complete shell that offered protection at every phase of its evolution, also when the bony component of the shell was not complete. This is backed by fossils of the freshwater Odontochelys semitestacea or "half-shelled turtle with teeth", from the late Triassic, which have been discovered near Guangling in southwest China. Odontochelys displays a complete bony plastron and an incomplete carapace, similar to an early stage of turtle embryonic growth. Just before this discovery, the particular earliest-known fossil turtle forefathers, like Proganochelys, were terrestrial and had a complete covering, offering no clue in order to the evolution of the impressive anatomical feature. From the past due Jurassic, turtles had radiated widely, and their precious history becomes better to go through.

Their specific ancestry offers been disputed. It has been believed they are the particular only surviving branch associated with the ancient evolutionary grade Anapsida, which includes organizations such as procolophonids, millerettids, protorothyrids, and pareiasaurs. All anapsid skulls lack a temporary opening while all other extant amniotes have temporary openings (although in mammals, the hole has turn out to be the zygomatic arch). The millerettids, protorothyrids, and pareiasaurs became extinct in the late Permian period plus the procolophonoids during the Triassic.

However , it was later recommended 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, somewhat closer to Squamata in order to Archosauria.[55][56] All molecular studies possess strongly upheld the placement of turtles within diapsids; some place turtles within Archosauria, or, more commonly, as a sister group to extant archosaurs,[58][59][60][61] though an analysis conducted by Lyson et al. (2012) recovered turtles because the sister group of lepidosaurs instead. Reanalysis of before phylogenies suggests that they will classified turtles as anapsids both simply because they assumed this classification (most of all of them studying what sort associated with anapsid turtles are) and because they did not really sample fossil and extant taxa broadly enough regarding constructing the cladogram. Testudines were suggested to have diverged from other diapsids between 200 and 279 million years ago, though the particular debate is far through settled. Even the traditional placement of turtles outside Diapsida cannot be dominated out at this point. A combined analysis associated with morphological and molecular data conducted by Lee (2001) found turtles to become anapsids (though a connection with archosaurs couldn't be statistically rejected).[64] Similarly, a morphological research conducted by Lyson ainsi que al.. (2010) recovered them as anapsids most closely related to Eunotosaurus. The molecular analysis of 248 nuclear genes from sixteen vertebrate taxa shows that turtles are a sister group to birds and crocodiles (the Archosauria).[66] The date of splitting up of turtles and parrots and crocodiles was estimated to be 255 mil years ago. The most current common ancestor of living turtles, corresponding towards the divided between Pleurodira and Cryptodira, was estimated to have happened around 157 million years ago. The oldest conclusive crown-group turtle (member from the modern clade Testudines) may be the species Caribemys oxfordiensis from the late Jurassic period (Oxfordian stage). Through utilizing the first genomic-scale phylogenetic analysis associated with ultraconserved elements (UCEs) to check into the placement of turtles within reptiles, Crawford ou al. (2012) also suggest that turtles are a sister group to parrots and crocodiles (the Archosauria).

The first genome-wide phylogenetic analysis was completed simply by Wang et al. (2013). Using the draft genomes of Chelonia mydas and Pelodiscus sinensis, the group used the largest turtle data set to date in their own analysis and concluded that turtles are likely the sister group of crocodilians and birds (Archosauria). This particular placement within the diapsids suggests that the turtle lineage lost diapsid head characteristics as it now possesses an anapsid-like skull.

The earliest known fully shelled member of the particular turtle lineage is the particular late Triassic Proganochelys. This particular genus already possessed numerous advanced turtle traits, and thus probably indicates many millions of years of preceding turtle evolution; this particular is further supported simply by evidence from fossil paths from the Early Triassic of the United Says (Wyoming and Utah) plus from the Middle Triassic of Germany, indicating that proto-turtles already existed as early as the first Triassic. Proganochelys lacked the opportunity to pull its head into the shell, had a long neck, and had a long, spiked tail closing in a club. While this body form is similar to that of ankylosaurs, it resulted from convergent advancement.

Turtles are divided directly into two extant suborders: Cryptodira and Pleurodira. The Cryptodira is the larger associated with the two groups and includes all the sea turtles, the terrestrial tortoises, and lots of of the fresh water turtles. The Pleurodira are usually sometimes known as the particular side-necked turtles, a reference to the way they retract their heads to their shells. This particular smaller group consists primarily of various freshwater turtles.