149-503: Chelonii - Oppel, 1811 Chlonopteria - Rafinesque, 1814 Cheloniae - Schmid, 1819 Edigitata - Haworth, 1825 Oiacopodae - Wagler, 1828 Pterodactyli - Mayer, 1849 Sea turtles (superfamily Chelonioidea ), sometimes called marine turtles , are reptiles of the order Testudines and of the suborder Cryptodira . The seven existing species of sea turtles are the flatback , green , hawksbill , leatherback , loggerhead , Kemp's ridley , and olive ridley . Six of
298-869: A critically endangered species in 2006 and is listed as endangered under the US Endangered Species Act . It is listed in Appendix II of the Convention on International Trade in Endangered Species (CITES) meaning international trade is regulated by the CITES permit system, and local laws are in place to control hunting. The non-governmental conservation organisation the Turtle Survival Alliance (TSA) has conducted at least two hickatee workshops in Belize in
447-441: A bacterial lung infection. D. mawii is herbivorous ; it is a generalist, feeding on aquatic plants , floating plants, shoreline emergents, bank vegetation and grasses depending on the habitat. Typically, these include Russell river grass ( Paspalum paniculatum ), among others. It will also eat fruit and flowers opportunistically. During the rainy season the waters rise a few metres, sometimes many, in some places this brings
596-574: A bony secondary palate which completely separates the oral and nasal cavities. The necks of turtles are highly flexible, possibly to compensate for their rigid shells. Some species, like sea turtles, have short necks while others, such as snake-necked turtles , have long ones. Despite this, all turtle species have eight neck vertebrae , a consistency not found in other reptiles but similar to mammals . Some snake-necked turtles have both long necks and large heads, limiting their ability to lift them when not in water. Some turtles have folded structures in
745-724: A drastic cull from over-harvesting, followed by population expansions. As it is almost certain the Ancient Maya were engaged in long distance trade in this turtle species and consumed large amounts, it was deemed most probable that the Maya were responsible for this (see section on interaction with humans below). Even today, turtles have been found trapped in small isolated ponds (called aguadas in Guatemala) where they would be unlikely to naturally disperse to, or in areas they do not naturally occur, likely moved there by people in order to harvest them at
894-477: A frequent flood, when nests are often submerged. In the culture of the Ancient Mayan civilisation this species and turtles in general had numerous uses such as being used in warfare, as musical instruments and as food, with this species likely being consumed by the elites during feasts. The Maya probably exported these turtles to areas where they do not occur, based on their shell remains in kitchen middens. There
1043-513: A hot day, and to fall naturally to around 29 °C (84 °F) by night. Some giant tortoises seek out shade to avoid overheating on sunny days. On Grand Terre Island , food is scarce inland, shade is scarce near the coast, and the tortoises compete for space under the few trees on hot days. Large males may push smaller females out of the shade, and some then overheat and die. Adult sea turtles, too, have large enough bodies that they can to some extent control their temperature. The largest turtle,
1192-523: A later date. Although most haplotypes were relatively closely related, there was one highly divergent haplotype which only showed up in four samples from Sarstún and Salinas, divergent enough to represent a possible new hyper-critically endangered cryptic species . Hydrological reproductive barriers between populations may have led to the main lineages splitting in the Pliocene to Pleistocene (3.73–0.227 million years ago), generally enough time to accumulate
1341-484: A less clear differentiation. Although some genetic structure was evident, most locations showed a high rate of mixing of different lineages, with two main closely related mitochondrial haplotypes dominating the population. Three divergent mitochondrial lineages were found: an extremely rare one dubbed '1D' only found in four samples from Sarstún and Salinas on the southeast edge of the Grijalva-Usumacinta basin,
1490-409: A low, flattened, smooth carapace with a median keel present in juveniles, it is usually a uniform brown, almost black, grey or olive in colour. The plastron is usually white to yellow, though may acquire substrate staining in some areas. In juveniles, a distinctive keel is found down the centre of the carapace, and the outer edges have serrations. These features are lost as the turtle ages. Its skin
1639-440: A major part of the otter diets, they hypothesise that otter predation is not significant, and also state that while there was ample evidence for otter predation in one part of Belize, this was the only place they had seen it occur. Campbell in 1998 notes that the otter is itself not common enough for this to be an issue. Especially large juveniles and subadults are preyed upon by otters in Belize. Otter predation can be recognised by
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#17328691835821788-419: A more fusiform body plan than their terrestrial or freshwater counterparts. This tapering at both ends reduces volume and means that sea turtles cannot retract their head and limbs into their shells for protection, unlike many other turtles and tortoises. However, the streamlined body plan reduces friction and drag in the water and allows sea turtles to swim more easily and swiftly. The leatherback sea turtle
1937-416: A propulsive force twice as large, and swim six times as fast, as freshwater turtles. The swimming efficiency of young marine turtles is similar to that of fast-swimming fish of open water, like mackerel . Compared to other reptiles, turtles tend to have reduced tails, but these vary in both length and thickness among species and between sexes. Snapping turtles and the big-headed turtle have longer tails;
2086-432: A rather random spatial distribution within one to three metres along a constantly shifting shoreline, the nests are extremely difficult to locate for humans, and finding eggs is very uncommon. In 1989 and 1990, despite nightly searches by a team during two seasons, only two nests were located. Polisar was never able to witness nesting himself, but three accounts from local hunters had the animals nesting within 1.5 metres from
2235-757: A second northernmost 'Papaloapan' lineage restricted to the Papaloapan basin in the state of Veracruz , to the west of the Sierra de Santa Marta and the Isthmus of Tehuantepec , and a third widespread 'central' lineage that was found in all studied localities. It appeared as if a formerly clear phylogeographical pattern had been obscured by transport and introductions of turtle populations from one waterway to another, i.e. secondary blurring by large-scale gene flow between populations. Low haplotype diversity at some localities indicated prehistoric population bottlenecks , possibly after
2384-607: A sex bias in dispersal. Also the populations from Sibun River , Lake Salpetén and Laguna Sacnab , all near the eastern edge of the distribution, were relatively well-differentiated from the remaining populations. This was thought to be due to losses of genetic variability from recent genetic drift and/or demographic isolation. All the other populations had high levels of gene flow, even between areas separated by geographic distances of more than 300 km. The study found that this suggests likely thousands of years of human-mediated trade, but that it might also just mean that this species
2533-517: A similar distribution have phylogeographic structure revealed in their genomes , with the population often being split into at least three subgroups representing the three main Atlantic hydrological basins of this region, the Papaloapan , Coatzacoalcos and Grijalva - Usumacinta . A 2011 study of the mitochondrial DNA (mtDNA) of extant populations throughout the range of this species, however, revealed
2682-485: A similar feeding strategy as otters, and typically target nesting females, other reports has them as predators of the eggs and hatchlings. Other predators of the eggs and hatchlings are coati ( Nasua narica ) and birds are also known to eat the eggs and hatchlings, namely the rails Aramides cajanea and Rallus longirostris , limpkins ( Aramus guarauna ) and the herons Butorides virescens , Nycticorax nycticorax and Nyctanassa violacea . A possible predator
2831-404: A softshell turtle may dive underwater and bury itself under the sea floor. If a predator persists, the turtle may bite or discharge from its cloaca. Several species produce foul-smelling chemicals from musk glands. Other tactics include threat displays and Bell's hinge-back tortoise can play dead . When attacked, big-headed turtle hatchlings squeal, possibly startling the predator. Turtles are
2980-461: A species may change with age, sex, and season, and may also differ between populations. In many species, juveniles are generally carnivorous but become more herbivorous as adults. With Barbour's map turtle , the larger female mainly eats mollusks while the male usually eats arthropods . Blanding's turtle may feed mainly on snails or crayfish depending on the population. The European pond turtle has been recorded as being mostly carnivorous much of
3129-401: A specific area, such as a beach, leaving the eggs to hatch unattended. The young turtles leave that area, migrating long distances in the years or decades in which they grow to maturity, and then return seemingly to the same area every few years to mate and lay eggs, though the precision varies between species and populations. This "natal homing" has appeared remarkable to biologists, though there
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#17328691835823278-541: A traditional feast food in the Tabasco community, where it is considered a mark of cultural identity. D. mawii is primarily prepared for the religious festivities of Lent and Semana Santa . In Belize these turtles are a culturally important food and popularly served as a traditional dish especially around the festivities of Easter, Christmas and La Ruta Maya, which is a canoe race in March attended by many people. A recipe from
3427-419: A turtle is unique among vertebrates and serves to protect the animal and provide shelter from the elements. It is primarily made of 50–60 bones and consists of two parts: the domed, dorsal (back) carapace and the flatter, ventral (belly) plastron . They are connected by lateral (side) extensions of the plastron. The carapace is fused with the vertebrae and ribs while the plastron is formed from bones of
3576-483: A week fed with commercial pellets for tilapia fish, Melampodium divaricatum and Eichhornia crassipes , sometimes with the odd vegetable. The reproductive adult females were injected with calcium supplements twice a year (March, after the end of the oviposition period, and June–July at the beginning of the courtship period). The Mexican government has stimulated the breeding of this species in captivity, and as of 2009 fourteen farms were officially registered with
3725-647: A worldwide distribution in the Jurassic and Cretaceous . The specific name , mawii , is in honour of the collector of the type specimen , Lieutenant Mawe of the British Navy. This species is usually vernacularly called tortuga blanca in Spanish, because it can be readily distinguished when prepared as food. When the meat of this turtle is cooked, it turns a white colour, unlike the more common turtle meat ( Trachemys scripta ), which colours dark. Many species sharing
3874-450: A worm-like appendage on its tongue that it uses to lure fish into its mouth. Tortoises are the most herbivorous group, consuming grasses, leaves, and fruits. Many turtle species, including tortoises, supplement their diet with eggshells, animal bones, hair, and droppings for extra nutrients. Turtles generally eat their food in a straightforward way, though some species have special feeding techniques. The yellow-spotted river turtle and
4023-463: Is a heavily exploited turtle; it is primarily harvested for its meat, exploitation of nesting females and their eggs is inconsequential because the nests are extremely hard to find. The species has been overhunted because it is valued by local people as a food, thus the meat fetches good prices. The turtle is now uncommon from much of its former range in southern Mexico. It was assessed by the IUCN as being
4172-492: Is a relatively large-bodied species, with records of 60 cm (24 in) straight carapace length and weights of 22 kg (49 lb); although most individuals are smaller. This is a herbivorous and almost completely aquatic turtle that does not even surface to bask. Bizarrely for reptiles, the eggs can remain viable even after being underwater for weeks -in the recent past, some scientists mistakenly claimed it nests underwater, likely due to visiting Central America during
4321-421: Is an absence of a clear phylogeographical pattern between the lineages and the collection localities, with different mitochondrial lineages interspersed amongst each other, which shows probable large-scale gene flow between populations. This can be explained by colonisation of the area by imported animals. Haplotype diversity was furthermore found to be quite low in some populations, which was explained as likely
4470-511: Is capable of moving great distances during its life. Besides microsatellite regions another part of the nuclear DNA was looked at, a 779 bp fragment of first intron of the RNA protein R35, with four haplotypes found. This revealed no phylogeographic structure: the main haplotype was common across the distribution, and the four individuals from Sarstún and Salinas all had this haplotype. The overall pattern
4619-501: Is clearly an extreme underestimate, as only the surface area of large water bodies and rivers was taken into account, and the lowest densities found in the area were used in the calculations in order to be conservative. Very high turtle densities were captured in Laguna Peru in 2007 and 2009. D. mawii is a nocturnal , completely aquatic turtle that does not bask or leave the water, except to lay eggs. The most significant predator
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4768-543: Is completely different in the alligator snapping turtle ( Macrochelys temminckii ), which is also often caught, but in which gene flow between populations is very low, but the mixed lineages are somewhat similar to the diamondback terrapin ( Malaclemys terrapin ), with translocations during the early twentieth century, or the radiated tortoise ( Geochelone radiata ) and gopher tortoises ( Gopherus polyphemus ), which show contemporary population structuring influenced by recent releases. The 2013 study concluded that as there
4917-504: Is experimental evidence that the embryos of Mauremys reevesii can move around inside their eggs to select the best temperature for development, thus influencing their sexual destiny. In other species, sex is determined genetically . The length of incubation for turtle eggs varies from two to three months for temperate species, and four months to over a year for tropical species. Species that live in warm temperate climates can delay their development . Hatching young turtles break out of
5066-462: Is genetic evidence that the Mayans and other ancient peoples may have hunted the turtle to local extinction in areas it now occurs in, and that some modern turtle populations stem from turtles introduced into waterways from elsewhere. The turtle also had mythological symbolism, although the true nature of Ancient Mayan myth has been largely obscured by time. Among the modern communities inheriting this land
5215-539: Is high during this period but significantly decreases when they reach adulthood. Most species grow quickly during their early years and slow down when they mature. Turtles can live long lives. The oldest living turtle and land animal is said to be a Seychelles giant tortoise named Jonathan , who turned 187 in 2019. A Galápagos tortoise named Harriet was collected by Charles Darwin in 1835; it died in 2006, having lived for at least 176 years. Most wild turtles do not reach that age. Turtles keep growing new scutes under
5364-399: Is highest in a horizontal band with retinal cells packed about twice as densely as elsewhere. This gives the best vision along the visual horizon. Sea turtles do not appear to use polarized light for orientation as many other animals do. The deep-diving leatherback turtle lacks specific adaptations to low light, such as large eyes, large lenses, or a reflective tapetum . It may rely on seeing
5513-400: Is important in some species, and female green sea turtles are not always receptive. As such, they have evolved behaviors to avoid the male's attempts at copulation, such as swimming away, confronting the male followed by biting or taking up a refusal position with her body vertical, her limbs widely outspread, and her plastron facing the male. If the water is too shallow for the refusal position,
5662-598: Is known from fossils is Nichollsemys from the Early Cretaceous ( Albian ) of Canada . In 2022, the giant fossil species Leviathanochelys was described from Spain . This species inhabited the oceans covering Europe in the Late Cretaceous and rivaled the concurrent giant protostegids such as Archelon and Protostega as one of the largest turtles to ever exist. Unlike the protostegids, which have an uncertain relationship to modern sea turtles, Leviathanochelys
5811-473: Is now plentiful evidence for it, including from genetics. How sea turtles navigate to their breeding beaches remains unknown. One possibility is imprinting as in salmon , where the young learn the chemical signature, effectively the scent, of their home waters before leaving, and remember that when the time comes for them to return as adults. Another possible cue is the orientation of the Earth's magnetic field at
5960-426: Is often complex in aquatic species, both marine and freshwater, but simpler in the semi-aquatic mud turtles and snapping turtles. A male tortoise bobs his head, then subdues the female by biting and butting her before mounting. The male scorpion mud turtle approaches the female from the rear, and often resorts to aggressive methods such as biting the female's tail or hind limbs, followed by a mounting. Female choice
6109-453: Is possibly a fourth type of cone that detects ultraviolet , as hatchling sea turtles respond experimentally to ultraviolet light, but it is unknown if they can distinguish this from longer wavelengths. A freshwater turtle, the red-eared slider , has an exceptional seven types of cone cell. Sea turtles orient themselves on land by night, using visual features detected in dim light. They can use their eyes in clear surface water, muddy coasts,
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6258-595: Is predominantly the same colour as the shell, with reddish or peach-coloured markings around the neck and underside. Adult males can often be differentiated from females by yellow (although sometimes cream or reddish-brown) markings on the top of their heads, as opposed to the uniformly dull-coloured heads of females, and longer, thicker tails. D. mawii lives in Atlantic-draining larger rivers and lakes in Central America, from southern Mexico through Belize to
6407-412: Is the jaguar ( Panthera onca ), which feeds on turtles in general by cracking the shell open to scoop out the contents. D. mawii hosts a number of specialised parasites . The fluke Caballerodiscus resupinatus is found in the intestine and C. tabascensis in the intestine and stomach, both have been found in Tabasco and Veracruz, Parachiorchis parviacetabulatus recorded from the intestine
6556-558: Is the largest sea turtle, reaching 1.4 to more than 1.8 m (4.6 to 5.9 ft) in length and weighing between 300 and 640 kg (661 to 1,411 lbs). Other sea turtle species are smaller, ranging from as little as 60 cm (2 ft) long in the case of the Kemp's ridley, which is the smallest sea turtle species, to 120 cm (3.9 ft) long in the case of the green turtle, the second largest. The skulls of sea turtles have cheek regions that are enclosed in bone. Although this condition appears to resemble that found in
6705-472: Is the leatherback. For each of the seven species of sea turtles, females and males are the same size. As adults, it is possible to tell male turtles from female turtles by their long tails with a cloacal opening near the tip. Adult female sea turtles have shorter tails, with a cloacal opening near the base. Hatchling and sub-adult turtles do not exhibit sexual dimorphism ; it is not possible to determine their sex by looking at them. In general, sea turtles have
6854-505: Is the only extant member of the family Dermochelyidae . Fossil evidence of marine turtles goes back to the Late Jurassic (150 million years ago) with genera such as Plesiochelys , from Europe. In Africa, the first marine turtle is Angolachelys , from the Turonian of Angola. A lineage of unrelated marine testudines, the pleurodire (side-necked) bothremydids , also survived well into
7003-501: Is the otter ( Lontra longicaudis ). Vogt et al . stated in 2011 that these otters are known to be able to keep turtle populations low in some cases by hindering recruitment , whereas Platt and Rainwater in 2011 claim that they are the first to register otter predation in this species, and note that because other otter species in Canada or Europe are not significant predators of other species of turtles and turtles are not believed to form
7152-557: Is thickened and used for butting and ramming during combat. Shells vary in flexibility. Some species, such as box turtles , lack the lateral extensions and instead have the carapace bones fully fused or ankylosed together. Several species have hinges on their shells, usually on the plastron, which allow them to expand and contract. Softshell turtles have rubbery edges, due to the loss of bones. The leatherback turtle has hardly any bones in its shell, but has thick connective tissue and an outer layer of leathery skin. The turtle's skull
7301-433: Is thought to be a true sea turtle of the superfamily Chelonioidea. Sea turtles' limbs and brains have evolved to adapt to their diets. Their limbs originally evolved for locomotion, but more recently evolved to aid them in feeding. They use their limbs to hold, swipe, and forage their food. This helps them eat more efficiently. Below is a cladogram showing the phylogenetic relationships of living and extinct sea turtles in
7450-497: Is thought to prevent them from collapsing. During exhalation, the contraction of the transversus abdominis muscle propels the organs into the lungs and expels air. Conversely, during inhalation, the relaxing and flattening of the oblique abdominis muscle pulls the transversus back down, allowing air back into the lungs. Although many turtles spend large amounts of their lives underwater, all turtles breathe air and must surface at regular intervals to refill their lungs. Depending on
7599-551: Is unique among living amniotes (which includes reptiles, birds and mammals); it is solid and rigid with no openings for muscle attachment ( temporal fenestrae ). Muscles instead attach to recesses in the back of the skull. Turtle skulls vary in shape, from the long and narrow skulls of softshells to the broad and flattened skull of the mata mata . Some turtle species have developed large and thick heads, allowing for greater muscle mass and stronger bites. Turtles that are carnivorous or durophagous (eating hard-shelled animals) have
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#17328691835827748-503: The Ancient Greek word χελώνη ( chelone ) 'tortoise'. Testudines is the official order name due to the principle of priority . The term chelonian is used as a formal name for members of the group. The largest living species of turtle (and fourth-largest reptile ) is the leatherback turtle , which can reach over 2.7 m (8 ft 10 in) in length and weigh over 500 kg (1,100 lb). The largest known turtle
7897-467: The Guatemalan - Honduran border. In Mexico it occurs in the states of Veracruz , Tabasco , Campeche , the north of Oaxaca , the north of Chiapas and the south of Quintana Roo , primarily in the hydrological basins of the Papaloapan , Coatzacoalcos and Grijalva - Usumacinta River systems. In Guatemala the species occurs from southern and central Petén Department , south to Lago de Izabal and
8046-809: The Late Cretaceous and Cenozoic , members of the pleurodire families Bothremydidae and Podocnemididae became widely distributed in the Northern Hemisphere due to their coastal habits. The oldest known soft-shelled turtles and sea turtles appeared during the Early Cretaceous . Tortoises originated in Asia during the Eocene . A late surviving group of stem-turtles, the Meiolaniidae , survived in Australasia into
8195-705: The Middle Triassic , and Eorhynchochelys of the Late Triassic lacked carapaces and plastrons but had shortened torsos, expanded ribs, and lengthened dorsal vertebrae. Also in the Late Triassic, Odontochelys had a partial shell consisting of a complete bony plastron and an incomplete carapace. The development of a shell reached completion with the Late Triassic Proganochelys , with its fully developed carapace and plastron. Adaptations that led to
8344-516: The Pleistocene and Holocene . Hickatee The hickatee ( Dermatemys mawii ) or in Spanish tortuga blanca ('white turtle'), also called the Central American river turtle , is the only living species in the family Dermatemydidae . The species is found in the Atlantic drainages of Central America, specifically Belize , Guatemala , southern Mexico and probably Honduras . It
8493-602: The Pleurodira (side necked turtles) and Cryptodira (hidden necked turtles), which differ in the way the head retracts. There are 360 living and recently extinct species of turtles, including land-dwelling tortoises and freshwater terrapins . They are found on most continents, some islands and, in the case of sea turtles , much of the ocean. Like other amniotes (reptiles, birds , and mammals ) they breathe air and do not lay eggs underwater, although many species live in or around water. Turtle shells are made mostly of bone ;
8642-513: The Secretaría del Medio Ambiente y Recursos Naturales , holding a few dozen to a few hundred turtles each. As a generalist herbivore fodder costs are low. However, growth rates are low. In 2011 some US scientists mused that commercial breeding might be cost effective using experimental aquatic polyculture systems with the turtles as a secondary income source, and shrimp as the main crop. The turtles could graze on weeds and grasses, and do not harm
8791-570: The bioluminescence of prey when hunting in deep water. Turtles have no ear openings; the eardrum is covered with scales and encircled by a bony otic capsule , which is absent in other reptiles. Their hearing thresholds are high in comparison to other reptiles, reaching up to 500 Hz in air, but underwater they are more attuned to lower frequencies. The loggerhead sea turtle has been shown experimentally to respond to low sounds, with maximal sensitivity between 100 and 400 Hz. Turtles have olfactory (smell) and vomeronasal receptors along
8940-403: The brackish -living diamondback terrapin secrete excess salt in a thick sticky substance from their tear glands . Because of this, sea turtles may appear to be "crying" when on land. Turtles, like other reptiles, have a limited ability to regulate their body temperature . This ability varies between species, and with body size. Small pond turtles regulate their temperature by crawling out of
9089-402: The coracoid . Both the shoulder and pelvic girdles of turtles are located within the shell and hence are effectively within the rib cage. The trunk ribs grow over the shoulder girdle during development. The shell is covered in epidermal (outer skin) scales known as scutes that are made of keratin , the same substance that makes up hair and fingernails. Typically, a turtle has 38 scutes on
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#17328691835829238-596: The larynx or glottis that vibrate to produce sound. Other species have elastin -rich vocal cords . Due to their heavy shells, turtles are slow-moving on land. A desert tortoise moves at only 0.22–0.48 km/h (0.14–0.30 mph). By contrast, sea turtles can swim at 30 km/h (19 mph). The limbs of turtles are adapted for various means of locomotion and habits and most have five toes. Tortoises are specialized for terrestrial environments and have column-like legs with elephant-like feet and short toes. The gopher tortoise has flattened front limbs for digging in
9387-411: The mtDNA of extant populations throughout the range of this species indicated that the population was likely highly impacted during Mayan times, and may have even been extirpated from certain areas, only to be restocked from other waterways. The mitochondrial divergences likely represent hydrological reproductive barriers between populations that may have existed for up to three million years, but there
9536-475: The nuclear DNA aimed to resolve this. This 2013 study found no sign of a recent bottleneck in the fifteen locations sampled, indicating that harvesting going for the past half century had not yet had an effect on genomic diversity, possibly a long generation time and delayed sexual maturity of D. mawii buffering against loss of genetic diversity despite population size reduction. The Sarstún and Salinas populations in general were not strongly differentiated from
9685-422: The painted turtle may filter feed by skimming the water surface with their mouth and throat open to collect particles of food. When the mouth closes, the throat constricts and water is pushed out through the nostrils and the gap in between the jaws. Some species employ a "gape-and-suck method" where the turtle opens its jaws and expands its throat widely, sucking the prey in. The diet of an individual within
9834-400: The pig-nosed turtle are the most specialized for swimming. Their front limbs have evolved into flippers while the shorter hind limbs are shaped more like rudders. The front limbs provide most of the thrust for swimming, while the hind limbs serve as stabilizers. Sea turtles such as the green sea turtle rotate the front limb flippers like a bird's wings to generate a propulsive force on both
9983-407: The shoulder girdle , sternum , and gastralia (abdominal ribs). During development, the ribs grow sideways into a carapacial ridge, unique to turtles, entering the dermis (inner skin) of the back to support the carapace. The development is signaled locally by proteins known as fibroblast growth factors that include FGF10 . The shoulder girdle in turtles is made up of two bones, the scapula and
10132-531: The snapping turtles (Chelydridae), musk turtles (Kinosternidae), and hickatee ( Dermatemyidae ) of the Americas, which alongside the sea turtles constitute the clade Americhelydia . The oldest possible representative of the lineage ( Panchelonioidea ) leading to modern sea turtles was possibly Desmatochelys padillai from the Early Cretaceous. Desmatochelys was a protostegid , a lineage that would later give rise to some very large species but went extinct at
10281-465: The "Polka Dot Ancestor" by Olivier Rieppel. The theory accounted for the evolution of fossil pareiasaurs from Bradysaurus to Anthodon , but not for how the ribs could have become attached to the bony dermal plates. More recent discoveries have painted a different scenario for the evolution of the turtle's shell. The stem -turtles Eunotosaurus of the Middle Permian , Pappochelys of
10430-447: The 1950s or 1960s advises pouring boiling water over the chopped pieces of hickatee to remove the thin skin, seasoning the meat with thyme, black pepper, onion, garlic and vinegar and letting it marinate overnight, cooking in hot oil, mixing with coconut cream and serving with rice. In the Petén highlands of Guatemala it is the most esteemed turtle because of its delicious flesh. D. mawii
10579-459: The 1980s, there was a general decrease in overall numbers and sighting localities. Interviews with locals indicate the 1993 laws are largely ineffective, hunting continues to be performed with in some areas with hundreds of turtles being caught in small parts of the Belize River , and the traditional Easter dish of the country continues to be served in rural restaurants. In 1997 Polisar claimed it
10728-427: The 238 turtles tested in 2011 had the more common central mitochondria, for conservation purposes. Although mtDNA can reveal deep genetic structure in populations, as it is only inherited via the mother, it does not show insofar different subpopulations are independently evolving units, because different populations may interbreed without this showing in the mtDNA of individuals. A subsequent 2013 study of eight loci of
10877-602: The Bladen River, the 1,200 acres (4.9 km ) property is situated among four protected areas ( Bladen Nature Reserve , Cockscomb Basin Jaguar Reserve , Deep River Forest Reserve and Maya Mountain Forest Reserve). The goal of the program was to generate hatchlings and release them for stocking purposes. As of 2006 it was kept at the following zoos: Veracruz Aquarium , Chicago Zoo , Detroit Zoo , Philadelphia Zoo (with
11026-456: The Cenozoic. Other pleurodires are also thought to have lived at sea, such as Araripemys and extinct pelomedusids . Modern sea turtles are not descended from more than one of the groups of sea-going turtles that have existed in the past; they instead constitute a single radiation that became distinct from all other turtles at least 110 million years ago. Their closest extant relatives are in fact
11175-456: The Chelonioidea based on Evers et al. (2019): † Toxochelys † Protostegidae [REDACTED] † Corsochelys Dermochelyidae [REDACTED] † Nichollsemys † Allopleuron Cheloniidae [REDACTED] † Argillochelys † Procolpochelys † Eochelone † Puppigerus † Ctenochelys † Peritresius † Cabindachelys An alternate phylogeny
11324-520: The Yucatán, it is clear that although all species of turtles were eaten, D. mawii was a luxury product of the elites. Some time later, in the mid-16th century, Spanish explorers of the Gulf Coast of Mexico relate that turtles were a common meal for them there. The turtles were also used for warfare by the Mayans, the carapace being used as a shield by Mayan warriors. Today the turtle remains much loved as
11473-596: The area corresponding to the Maya Biosphere Reserve , with the researchers reporting that it was quite common almost everywhere, and extending the known distribution somewhat with the Río Azul in Mirador-Río Azul National Park and Playa Grande, Quiche. Based on an extrapolation of the turtle densities obtained in this survey, 4,081 turtles are estimated to currently exist within this area. This number
11622-504: The back of the female's plastron. Aquatic turtles mount in water, and female sea turtles support the mounting male while swimming and diving. During copulation, the male turtle aligns his tail with the female's so he can insert his penis into her cloaca. Some female turtles can store sperm from multiple males and their egg clutches can have multiple sires. Turtles, including sea turtles, lay their eggs on land, although some lay eggs near water that rises and falls in level, submerging
11771-449: The carapace and 16 on the plastron, giving them 54 in total. Carapace scutes are divided into "marginals" around the margin and "vertebrals" over the vertebral column, though the scute that overlays the neck is called the "cervical". "Pleurals" are present between the marginals and vertebrals. Plastron scutes include gulars (throat), humerals, pectorals, abdominals, and anals. Side-necked turtles additionally have "intergular" scutes between
11920-443: The central type individuals, and these individuals occurred at relatively low frequencies amongst the central type haplotypes shared with adjacent populations to the east of the isthmus, indicating significant gene flow of mitochondrial lineages westwards across the isthmus. At the same time nuclear microsatellites appear to show gene flow in the other direction. Such conflicting signals could be caused by different episodes, or be due to
12069-436: The darkness of the deep ocean, and also above water. Unlike in terrestrial turtles, the cornea (the curved surface that lets light into the eye) does not help to focus light on the retina, so focusing underwater is handled entirely by the lens, behind the cornea. The cone cells contain oil droplets placed to shift perception toward the red part of the spectrum, improving color discrimination. Visual acuity, studied in hatchlings,
12218-487: The earliest known fossil reptiles (anapsids), it is possible it is a more recently evolved trait in sea turtles, placing them outside the anapsids. Sea turtles, along with other turtles and tortoises, are part of the order Testudines . All species except the leatherback sea turtle are in the family Cheloniidae . The superfamily name Chelonioidea and family name Cheloniidae are based on the Ancient Greek word for tortoise: χελώνη ( khelōnē ). The leatherback sea turtle
12367-496: The early 2010s where attendees were taught net capture techniques, measuring captured turtles and recording the information on standard collection sheets. A countrywide survey of the population in Belize in 1983 and 1984 found that the species was common and abundant in some areas, but declining in population in more human-populated areas. Research in north-central Belize from 1989 through 1991 determined that harvesting rates in human-populated areas were unsustainable. As such, in 1993
12516-595: The eggs. While most species build nests and lay eggs where they forage, some travel miles. The common snapping turtle walks 5 km (3 mi) on land, while sea turtles travel even further; the leatherback swims some 12,000 km (7,500 mi) to its nesting beaches. Most turtles create a nest for their eggs. Females usually dig a flask-like chamber in the substrate. Other species lay their eggs in vegetation or crevices. Females choose nesting locations based on environmental factors such as temperature and humidity, which are important for developing embryos. Depending on
12665-514: The end of the Cretaceous. Presently thought to be outside the crown group that contains modern sea turtles (Chelonioidea), the exact relationships of protostegids to modern sea turtles are still debated due to their primitive morphology; they may be the sister group to the Chelonoidea, or an unrelated turtle lineage that convergently evolved similar adaptations. The earliest "true" sea turtle that
12814-446: The entire group. The name of the order, Testudines ( / t ɛ ˈ s tj uː d ɪ n iː z / teh- STEW -din-eez ), is based on the Latin word testudo 'tortoise'; and was coined by German naturalist August Batsch in 1788. The order has also been historically known as Chelonii ( Latreille 1800) and Chelonia (Ross and Macartney 1802), which are based on
12963-522: The environment using landmarks and a map-like system resulting in accurate direct routes towards a goal. Navigation in turtles have been correlated to high cognition function in the medial cortex region of the brain. When sensing danger, a turtle may flee, freeze or withdraw into its shell. Freshwater turtles flee into the water, though the Sonora mud turtle may take refuge on land as the shallow temporary ponds they inhabit make them vulnerable. When startled,
13112-643: The evolution of the shell may have originally been for digging and a fossorial lifestyle. The oldest known members of the Pleurodira lineage are the Platychelyidae , from the Late Jurassic . The oldest known unambiguous cryptodire is Sinaspideretes , a close relative of softshell turtles, from the Late Jurassic of China. Turtles became highly diverse during the Cretaceous, as climatic conditions in this period were favourable for their global dispersal. During
13261-525: The females resort to beaching themselves, as the males do not follow them ashore. All turtles fertilize internally; mounting and copulation can be difficult. In many species, males have a concave plastron that interlocks with the female's carapace. In species like the Russian tortoise , the male has a lighter shell and longer legs. The high, rounded shape of box turtles are particular obstacles for mounting. The male eastern box turtle leans backward and hooks onto
13410-459: The genetic divergences for speciation to occur. The sampling locations, however, also contained the common central haplotypes. The existence of such divergent genes led Vogt et al . to recommended splitting up the taxon into three evolutionary significant units , corresponding to the Sarstun, Salinas, and Papaloapan populations, and something called a 'management unit' for the locations where all of
13559-417: The government of Belize instituted a number of new laws meant to control hunting and forbid trade. Hunting was forbidden in a certain closed season, hunters were allowed to bag no more than three turtles, and females above a certain size have to be released. A series of protected zones were established in a number of the major waterways in northern Belize. A 1998 and 1999 survey in north-central Belize found that
13708-471: The gulars. Turtle scutes are usually structured like mosaic tiles, but some species, like the hawksbill sea turtle , have overlapping scutes on the carapace. The shapes of turtle shells vary with the adaptations of the individual species, and sometimes with sex . Land-dwelling turtles are more dome-shaped, which appears to make them more resistant to being crushed by large animals. Aquatic turtles have flatter, smoother shells that allow them to cut through
13857-628: The head are insulated by fat around the neck. Most turtle species are opportunistic omnivores; land-dwelling species are more herbivorous and aquatic ones more carnivorous . Generally lacking speed and agility, most turtles feed either on plant material or on animals with limited movements like mollusks, worms, and insect larvae. Some species, such as the African helmeted turtle and snapping turtles, eat fish, amphibians, reptiles (including other turtles), birds, and mammals. They may take them by ambush but also scavenge. The alligator snapping turtle has
14006-399: The laboratory, Florida red-bellied cooters can learn novel tasks and have demonstrated a long-term memory of at least 7.5 months. Similarly, giant tortoises can learn and remember tasks, and master lessons much faster when trained in groups. Tortoises appear to be able to retain operant conditioning nine years after their initial training. Studies have shown that turtles can navigate
14155-633: The latter uses it for balance while climbing. The cloaca is found underneath and at the base, and the tail itself houses the reproductive organs. Hence, males have longer tails to contain the penis. In sea turtles, the tail is longer and more prehensile in males, who use it to grasp mates. Several turtle species have spines on their tails. Turtles make use of vision to find food and mates, avoid predators, and orient themselves. The retina 's light-sensitive cells include both rods for vision in low light, and cones with three different photopigments for bright light, where they have full-color vision. There
14304-408: The leatherback, can swim in the waters off Nova Scotia , which may be as cold as 8 °C (46 °F), while their body temperature has been measured at up to 12 °C (22 °F) warmer than the surrounding water. To help keep their temperature up, they have a system of countercurrent heat exchange in the blood vessels between their body core and the skin of their flippers. The vessels supplying
14453-410: The leaves and branches of terrestrial trees within the jaws of this turtle and it will largely browse on this during this season, in other places the water floods pastures, and the turtle will primarily graze upon the submerged grass. The habitat appears to be the main factor impacting diet -in many rivers the water is too strong or the waters to muddy to sustain aquatic plant-life, and in these waters
14602-536: The literature. However, it is possible that a combination of a diapause and variable local reproductive cues is responsible for this. There appears to be a primary breeding season timed with the later part of the rainy season (September to December) and a secondary one at the beginning of the dry season (January to February). The species can lay up to 4 clutches per year with an average of 2–20 eggs per clutch; clutch sizes over 15, however, were not common. As this species often buries its eggs in more than one nests with
14751-549: The lungs via the pulmonary artery , or to the body via the aorta . The ability to separate the two outflows varies between species. The leatherback has a powerful muscular ridge enabling almost complete separation of the outflows, supporting its actively swimming lifestyle. The ridge is less well developed in freshwater turtles like the sliders ( Trachemys ). Turtles are capable of enduring periods of anaerobic respiration longer than many other vertebrates. This process breaks down sugars incompletely to lactic acid , rather than all
14900-447: The lungs, as in other amniotes, so they have had to evolve special adaptations for respiration. The lungs of turtles are attached directly to the carapace above while below, connective tissue attaches them to the organs. They have multiple lateral (side) and medial (middle) chambers (the numbers of which vary between species) and one terminal (end) chamber. The lungs are ventilated using specific groups of abdominal muscles attached to
15049-464: The manner by which they typically chew off the heads, tail and limbs, sometimes slurping out the entrails, but leave the shell intact. The crocodiles Crocodylus moreletii and C. acutus usually feed on juveniles and hatchlings, or intermediate-sized turtles. Crocodiles crush the shell and swallow the turtle whole. The indigo snake Drymarchon melanurus preys on the eggs and hatchlings. According to one report raccoons ( Procyon lotor ) have
15198-508: The most powerful bites. For example, the durophagous Mesoclemmys nasuta has a bite force of 432 lbf (1,920 N). Species that are insectivorous , piscivorous (fish-eating), or omnivorous have lower bite forces. Living turtles lack teeth but have beaks made of keratin sheaths along the edges of the jaws. These sheaths may have sharp edges for cutting meat, serrations for clipping plants, or broad plates for breaking mollusks . Sea turtles, and several extinct forms, have evolved
15347-401: The nasal cavity, the latter of which are used to detect chemical signals. Experiments on green sea turtles showed they could learn to respond to a selection of different odorant chemicals such as triethylamine and cinnamaldehyde , which were detected by olfaction in the nose. Such signals could be used in navigation. The rigid shell of turtles is not capable of expanding and making room for
15496-422: The natal beach. There is experimental evidence that turtles have an effective magnetic sense, and that they use this in navigation . Proof that homing occurs is derived from genetic analysis of populations of loggerheads, hawksbills, leatherbacks, and olive ridleys by nesting place. For each of these species, the populations in different places have their own mitochondrial DNA genetic signatures that persist over
15645-448: The neck of the urinary bladder and above the pubis . Arid-living tortoises have bladders that serve as reserves of water, storing up to 20% of their body weight in fluids. The fluids are normally low in solutes , but higher during droughts when the reptile gains potassium salts from its plant diet. The bladder stores these salts until the tortoise finds fresh drinking water. To regulate the amount of salt in their bodies, sea turtles and
15794-517: The neighbouring populations, but the four individuals from Sarstún and Salinas with divergent mitochondria did have divergent microsatellite loci sequences in varying amounts according to the individual, with three rare alleles only found in this subpopulation of four. The samples from Papaloapan locations were highly differentiated compared to almost all other populations, and also were rich in unique alleles. However, individuals carrying Papaloapan-type mtDNA haplotypes did not appear differentiated from
15943-403: The only country where it is still legal to hunt these animals, it is still common in some areas, but populations are depressed in areas where people live. In Mexico the state of the population is unclear -it was said to be almost extirpated from Mexico in 2006 based on an entry in a book from the 1970s, but reasonable amounts are still caught in areas such as Tabasco and Quintana Roo . In Guatemala
16092-410: The only reptiles that migrate long distances to lay their eggs on a favored beach. Turtles have appeared in myths and folktales around the world. Some terrestrial and freshwater species are widely kept as pets. Turtles have been hunted for their meat, for use in traditional medicine, and for their shells. Sea turtles are often killed accidentally as bycatch in fishing nets. Turtle habitats around
16241-476: The only reptiles that migrate long distances, more specifically the marine species that can travel up to thousands of kilometers. Some non-marine turtles, such as the species of Geochelone (terrestrial), Chelydra (freshwater), and Malaclemys (estuarine), migrate seasonally over much shorter distances, up to around 27 km (17 mi), to lay eggs. Such short migrations are comparable to those of some lizards, snakes, and crocodilians. Sea turtles nest in
16390-406: The organs that pull and push on them. Specifically, it is the turtle's large liver that compresses the lungs. Underneath the lungs, in the coelomic cavity , the liver is connected to the right lung by the root , and the stomach is directly attached to the left lung, and to the liver by a mesentery . When the liver is pulled down, inhalation begins. Supporting the lungs is a wall or septum , which
16539-568: The polar regions. The flatback sea turtle is found solely on the northern coast of Australia . The Kemp's ridley sea turtle is found solely in the Gulf of Mexico and along the East Coast of the United States . Testudines Turtles are reptiles of the order Testudines , characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups,
16688-426: The previous scutes every year, allowing researchers to estimate how long they have lived. They also age slowly . The survival rate for adult turtles can reach 99% per year. Zoologists have sought to explain the evolutionary origin of the turtles, and in particular of their unique shells. In 1914, Jan Versluys proposed that bony plates in the dermis, called osteoderms , fused to the ribs beneath them, later called
16837-417: The remains of what appear to be Ancient Mayan feasts, wherein large numbers of turtles were roasted. Such remains are also found in areas, such as the eastern and northern Yucatán , where the species is not believed to occur today. This could be due to import during Mayan times, or represent a distribution it is now extirpated from, or modern scientists simply have not looked properly here. A 2011 study of
16986-415: The result of bottlenecks resulting from over-harvesting during Mayan followed by population expansions. A later genetic study refined this story and largely supported it, but proposed alternate explanations. Bottlenecks were not found to be caused by recent hunting pressure in this study (see genetics section above). According to a study by Götz which looked at the contents of different kitchen middens in
17135-423: The resulting low oxygen levels. They can moderate the increase in acidity during anaerobic (non-oxygen-based) respiration by chemical buffering and they can lie dormant for months, in aestivation or brumation . The heart has two atria but only one ventricle . The ventricle is subdivided into three chambers. A muscular ridge enables a complex pattern of blood flow so that the blood can be directed either to
17284-444: The returned oxygenated blood through the body's tissues. The cardiopulmonary system has both structural and physiological adaptations that distinguish it from other vertebrates. Turtles have a large lung volume and can move blood through non-pulmonary blood vessels, including some within the heart, to avoid the lungs while they are not breathing. They can hold their breath for much longer periods than other reptiles and they can tolerate
17433-621: The rivers which drain into it. The presence and status in the Río Motagua bordering Honduras was unknown in 2011. It is reasonably common in the Pasión River and its tributaries as well as several lakes in Petén as of 1998. It was once common in Lake Petén Itzá , but by 1998 had become rarer there. It is well protected in Yaxhá Lake . In 2007 it was found to occur throughout northern Petén in
17582-420: The same nest were incubated and separated into two groups, with the hatchlings in one group being fed adult faeces and other group lacking this food additive , found that the young which snacked on excrement grew much faster than their peers. In green iguanas the behaviour of young feeding on adult dung is known to be important, but it is unknown if this means that turtle hatchlings also exhibit this behaviour in
17731-646: The seven sea turtle species, all but the flatback, are present in U.S. waters, and are listed as endangered and/or threatened under the Endangered Species Act . All but the flatback turtle are listed as threatened with extinction globally on the IUCN Red List of Threatened Species. The flatback turtle is found only in the waters of Australia, Papua New Guinea, and Indonesia. Sea turtles can be categorized as hard-shelled ( cheloniid ) or leathery-shelled ( dermochelyid ). The only dermochelyid species of sea turtle
17880-405: The shell using an egg tooth , a sharp projection that exists temporarily on their upper beak. Hatchlings dig themselves out of the nest and find safety in vegetation or water. Some species stay in the nest for longer, be it for overwintering or to wait for the rain to loosen the soil for them to dig out. Young turtles are highly vulnerable to predators, both in the egg and as hatchlings. Mortality
18029-482: The shoreline. In 1996 Polisar published that it was quite possible that the turtles nest underwater like the Australian Chelodina rugosa , a claim repeated as a certainty in later works, but in 2011 Vogt et al . dismiss the claim as invented by 'locals' confused by the constantly rising and falling waters of their homeland. D. mawii has been hunted for food for millennia. Archaeologists have recovered
18178-476: The shrimp. A three year pilot study was done in Veracruz, after the pond weeds were consumed the turtles were fed grass clippings, and the turtles reproduced each year. A project conducted by TSA on Belize Foundation for Research and Environmental Education property began in early 2011 focused on generating food plants and exploring husbandry details, such as egg laying and incubation. Located in southern Belize along
18327-502: The skin of these turtles, as well as a number of other Kinosternon mud turtles in other parts of southern Mexico. A study on the blood of turtles collected in the wild in Pantanos de Centla Biosphere Reserve and a turtle breeding farm, both located in Tabasco, found 100% of the wild turtles were infected with a species of Haemogregarina , a protozoan parasite inhabiting the red blood cells of turtles and spread by leeches. The protozoan
18476-464: The species is abundant in some areas, but uncommon elsewhere. Although in the 1990s scientists dismissed breeding this species as impracticable, it is now known they can reproduce in even quite poor waters, and as a generalist herbivorous species fodder costs are low. Much has been discovered regarding their animal husbandry , with some US scientists now musing that commercial breeding might be cost effective using experimental polyculture systems with
18625-400: The species was still common in remote areas, but was also still declining in more populated areas. A 2010 countrywide survey indicated that the population was much the same as in the previous surveys, depressed in human-populated areas, but healthy populations continue to exist in more remote areas. Although there was not much difference between the situation of the population in 2010 compared to
18774-413: The species, immersion periods vary between a minute and an hour. Some species can respire through the cloaca , which contains large sacs that are lined with many finger-like projections that take up dissolved oxygen from the water. Turtles share the linked circulatory and pulmonary (lung) systems of vertebrates, where the three-chambered heart pumps deoxygenated blood through the lungs and then pumps
18923-830: The species, the number of eggs laid varies from one to over 100. Larger females can lay eggs that are greater in number or bigger in size. Compared to freshwater turtles, tortoises deposit fewer but larger eggs. Females can lay multiple clutches throughout a season, particularly in species that experience unpredictable monsoons . Most mother turtles do no more in the way of parental care than covering their eggs and immediately leaving, though some species guard their nests for days or weeks. Eggs vary between rounded, oval, elongated, and between hard- and soft-shelled. Most species have their sex determined by temperature . In some species, higher temperatures produce females and lower ones produce males, while in others, milder temperatures produce males and both hot and cold extremes produce females. There
19072-424: The substrate. Freshwater turtles have more flexible legs and longer toes with webbing , giving them thrust in the water. Some of these species, such as snapping turtles and mud turtles , mainly walk along the water bottom, as they would on land. Others, such as terrapins, swim by paddling with all four limbs, switching between the opposing front and hind limbs, which keeps their direction stable. Sea turtles and
19221-479: The sun -water turtles plopping back into the water as one walks past a lake is a common experience in tropical and subtropical climates. This species does not bask, maintaining the same body temperature as the waters which surround it. Thus this means that it likely has a specialised gut flora to help it break down its food, but the particulars of this have not adequately been explored. One experiment found that symbiotic microorganisms must aid in digestion -when eggs from
19370-405: The time they are in the egg to when they are adults. These vocalizations may serve to create group cohesion when migrating . The oblong turtle has a particularly large vocal range; producing sounds described as clacks, clicks, squawks, hoots, various kinds of chirps, wails, hooos , grunts, growls, blow bursts, howls, and drum rolls. Play behavior has been documented in some turtle species. In
19519-399: The turtle continues to be eagerly sought as a dish eaten during important cultural events. The meat of this turtle is said to be very tasty. It has thus had a long history of exploitation. This has prompted Western conservationists to declare this use unsustainable, and that the turtle is now ' critically endangered ', especially singling out the people of Tabasco as the culprits. In Belize,
19668-456: The turtles as a secondary income source. The Mexican government already stimulated the farming of this species in the 2000s, there are now likely a few thousand kept in captivity there. The health of these captive animals is not ideal, and the success of these operations is unclear. Dermatemys mawii is the only living species in the family Dermatemydidae . Its closest relatives are only known from fossils with some 19 genera described from
19817-517: The turtles feed on plants growing on the banks. Where the banks are too steep for such plants, here the turtles feed on leaves of overhanging branches. It feeds during the night, spending most of the day underwater, generally in the deepest parts, usually near or under large branches and likewise, and often half-buried in the mud. Because leafy vegetables are low-energy foods requiring extensive digestion, and reptiles are cold-blooded , herbivorous reptiles usually try to speed things up by basking in
19966-620: The upper part is the domed carapace , while the underside is the flatter plastron or belly-plate. Its outer surface is covered in scales made of keratin , the material of hair, horns, and claws. The carapace bones develop from ribs that grow sideways and develop into broad flat plates that join up to cover the body. Turtles are ectotherms or "cold-blooded", meaning that their internal temperature varies with their direct environment. They are generally opportunistic omnivores and mainly feed on plants and animals with limited movements. Many turtles migrate short distances seasonally. Sea turtles are
20115-468: The upstroke and on the downstroke. This is in contrast to similar-sized freshwater turtles (measurements having been made on young animals in each case) such as the Caspian turtle , which uses the front limbs like the oars of a rowing boat, creating substantial negative thrust on the recovery stroke in each cycle. In addition, the streamlining of the marine turtles reduces drag. As a result, marine turtles produce
20264-449: The water and basking in the sun, while small terrestrial turtles move between sunny and shady places to adjust their temperature. Large species, both terrestrial and marine, have sufficient mass to give them substantial thermal inertia , meaning that they heat up or cool down over many hours. The Aldabra giant tortoise weighs up to some 60 kilograms (130 lb) and is able to allow its temperature to rise to some 33 °C (91 °F) on
20413-404: The water. Sea turtles in particular have streamlined shells that reduce drag and increase stability in the open ocean. Some turtle species have pointy or spiked shells that provide extra protection from predators and camouflage against the leafy ground. The lumps of a tortoise shell can tilt its body when it gets flipped over, allowing it to flip back. In male tortoises, the tip of the plastron
20562-403: The way to carbon dioxide and water as in aerobic (oxygen-based) respiration . They make use of the shell as a source of additional buffering agents for combating increased acidity, and as a sink for lactic acid. In sea turtles, the bladder is one unit and in most freshwater turtles, it is double-lobed. Sea turtle bladders are connected to two small accessory bladders, located at the sides to
20711-585: The wild. The intestines of these turtles are commonly swarming with nematodes -again, in iguanas of the Cyclura genus similar worms appear to aid in digestion, but in this case it is unknown if they are parasites, commensals or symbionts . Captured D. mawii will occasionally, however, eat fish . Juveniles in captivity tend to more readily accept animal matter as food which may show that young D. mawii are more apt to be carnivorous. The exact reproductive season for this species, D. mawii , has been confused in
20860-684: The world are being destroyed. As a result of these pressures, many species are extinct or threatened with extinction. The word turtle is borrowed from the French word tortue or tortre 'turtle, tortoise '. It is a common name and may be used without knowledge of taxonomic distinctions. In North America, it may denote the order as a whole. In Britain, the name is used for sea turtles as opposed to freshwater terrapins and land-dwelling tortoises. In Australia, which lacks true tortoises (family Testudinidae), non-marine turtles were traditionally called tortoises, but more recently turtle has been used for
21009-578: The year but switching to water lilies during the summer. Some species have developed specialized diets such as the hawksbill, which eats sponges , the leatherback, which feeds on jellyfish , and the Mekong snail-eating turtle . While popularly thought of as mute, turtles make various sounds to communicate. One study which recorded 53 species found that all of them vocalized. Tortoises may bellow when courting and mating. Various species of both freshwater and sea turtles emit short, low-frequency calls from
21158-752: The years. This shows that the populations are distinct and that homing must be occurring reliably. Turtles have a wide variety of mating behaviors but do not form pair-bonds or social groups. In green sea turtles, females generally outnumber males. In terrestrial species, males are often larger than females and fighting between males establishes a dominance hierarchy for access to mates. For most semi-aquatic and bottom-walking aquatic species, combat occurs less often. Males of these species instead may use their size advantage to mate forcibly . In fully aquatic species, males are often smaller than females and rely on courtship displays to gain mating access to females. Courtship varies between species, and with habitat. It
21307-415: Was Archelon ischyros , a Late Cretaceous sea turtle up to 4.5 m (15 ft) long, 5.25 m (17 ft) wide between the tips of the front flippers, and estimated to have weighed over 2,200 kg (4,900 lb). The smallest living turtle is Chersobius signatus of South Africa, measuring no more than 10 cm (3.9 in) in length and weighing 172 g (6.1 oz). The shell of
21456-749: Was evidence of substantial genetic mingling the species was best regarded as a single cohesive 'management unit' for conservation purposes, as opposed to Vogt et al . in 2011. The sample size of the individuals with the 1D mitochondria was too small to calculate insofar they represent a taxonomically relevant cryptic species. D. mawii It is a relatively large-bodied species, with historical records of 60 cm (24 in) straight carapace length and weights of 22 kg (49 lb); however, more recent records have found few individuals over 14 kg (31 lb) in Mexico or 11 kg (24 lb) in Guatemala. It has
21605-445: Was more prevalent during the rainy season . 27% of the wild turtles had leeches feeding off them, with no apparent detrimental effect on the hosts. The captive turtles were uninfected by both, but more unhealthy in other ways, wild turtles were better fed, bigger, and exhibited no real damage to the shell or major wounds. On a turtle farm in Veracruz it was noticed that turtles kept out of water for any period were highly susceptible to
21754-457: Was only found once in Veracruz, Pseudocleptodiscus margaritae recorded from the intestine was only found twice in Tabasco, Dermatemytrema trifoliatum in the intestine and stomach from Oaxaca, Tabasco and Veracruz, Octangioides skrjabini was recorded from the intestine and only found once in Tabasco, whereas O. tlacotalpensis was recorded from the intestine and only found in two localities in Veracruz, and lastly Choanophorus rovirosai
21903-507: Was proposed by Castillo-Visa et al. (2022): † Toxochelyidae † Protostegidae † Corsochelys † Eosphargis Dermochelys † Nichollsemys † Leviathanochelys † Allopleuron † Procolpochelys † Argillochelys † Eochelone † Puppigerus † Cabindachelys † Ctenochelys † Peritresius Natator Eretmochelys Chelonia Lepidochelys kempii Caretta Lepidochelys olivacea Sea turtles can be found in all oceans except for
22052-537: Was rarely found in captivity , and that breeding would probably be impractical because he thought the nesting behaviour was complicated in this species. He seems to be somewhat wrong in this. The first turtle farm in Mexico has been operating in Nacajuca , Tabasco, since the 1980s when it began as a rescue centre. It is the largest captive breeding facility for Dermatemys today, with a population of about 700 individuals in 2006, and 800 in 2011. The turtles were three times
22201-450: Was recorded from the intestine in Tabasco and Veracruz. All of these eight fluke species are only known to be hosted by D. mawii . Serpinema trispinosum is a parasitic nematode (also see entry on diet below) which has been recovered from a wide variety of freshwater turtles in North and Central America. Species of Placobdella , a type of leech, have been Chiapas found to suck blood from
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