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28-691: The Arrau turtle ( Podocnemis expansa ), also known as the South American river turtle , giant South American turtle , giant Amazon River turtle , Arrau sideneck turtle , Amazon River turtle or simply the Arrau , is the largest of the side-neck turtles ( Pleurodira ) and the largest freshwater turtle in Latin America . The species primarily feeds on plant material and typically nests in large groups on beaches. Due to hunting of adults, collecting of their eggs, pollution, habitat loss, and dams ,

56-418: Is due to the introduction of invasive species . Invasive species invade and exploit a new habitat for its natural resources as a method to outcompete the native organisms, eventually taking over the habitat. This can lead to either the native species' extinction or causing them to become endangered, which also eventually causes extinction. Plants and animals may also go extinct due to disease. The introduction of

84-450: Is slow to mature; some have suggested that females reach maturity when 4–8 years old and others have suggested about 17 years old. Their social behavior, especially at certain nesting beaches, makes them and their eggs vulnerable to humans. In addition to being used for food, they are sometimes used in traditional medicine . At the main known nesting beaches, it is estimated that the number of nests fell from 34,000 in 1963 to 4,700 in 1981. In

112-761: The Pelomedusidae , also known as the African mud terrapins, and the Podocnemididae , also known as the American side-neck river turtles. However, they were cosmopolitan clade during the Cretaceous and most of the Cenozoic , and even occurred in marine environments around the world. The Pleurodira are identified by the method with which they withdraw their heads into their shells. In these turtles,

140-431: The carapace length is up to 1.07 m (3.5 ft). Most individuals are considerably smaller with the average adult female having a carapace length of 64–71 cm (2.1–2.3 ft) and the average adult male 40–50 cm (1.3–1.6 ft). In addition to an overall smaller size, males can be recognized by their longer tail and straighter carapace than the females. Arrau turtles are brown, gray or olive -green, but

168-462: The cervical vertebrae . All extant turtles studied so far have eight vertebrae in the neck. In the Pleurodira, these vertebrae are narrow in cross-section and spool-shaped with biconvex centra on one or more of the cervicals. These centra act as a double joint, allowing a large degree of sideways movement and providing a means of folding the neck onto itself in the lateral plane. Conversely, in

196-567: The loss of biodiversity . This is along with natural forces that may create stress on the species or cause an animal population to become extinct. Currently the biggest reason for species extinction is human interaction resulting in habitat loss. Species rely on their habitat for the resources needed for their survival. If the habitat becomes destroyed, the population will see a decline in their numbers. Activities that cause loss of habitat include pollution , urbanization , and agriculture . Another reason for plants and animals to become endangered

224-636: The side-necked turtles and the name Pleurodira quite literally translates to side neck, whereas the Cryptodira are known as hidden-necked turtles. The Pleurodira turtles are currently restricted to freshwater habitats in the Southern Hemisphere, largely to Australia, South America, and Africa. Within the Pleurodira, three living families are represented: Chelidae , also known as the Austro-South American side-necked turtles,

252-399: The "connect to newly hatched young" sound, four primary sounds have been documented during the nesting season: one used during migration, one before basking, one when nesting at night and finally one when in the water after nesting. They can reach an age of 20 years or more in the wild, and captives have lived for at least 25 years. Based on certain scientific models it has been estimated that

280-658: The Arrau turtle is seriously threatened. Arrau turtles are found in the Amazon , Orinoco and Essequibo basins in Brazil, Bolivia, Peru, Ecuador, Colombia, Venezuela and Guyana. On occasion, typically after floods, individuals turn up in Trinidad . They are found in deep rivers, ponds, freshwater lagoons and flooded forest in white- , black- and clear-water . Arrau turtles can reach up to 90 kg (200 lb) in weight and

308-405: The Cryptodira, the neck bones are wide and flat. The biconvex centra in some of the cryptodiran cervicals allow the neck to fold onto itself in the vertical plane. Pleurodirans also differ from cryptodirans in the emarginations of their skulls. Skull emargination provides room and anchorage for the jaw muscles. The connection points and the position of the emarginations relate to different bones of

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336-464: The IUCN Red List does not consider a species extinct until extensive targeted surveys have been conducted, species that are possibly extinct are still listed as Critically Endangered. IUCN maintains a list of "possibly extinct" and "possibly extinct in the wild" species, modelled on categories used by BirdLife International to categorize these taxa . To be defined as Critically Endangered in

364-480: The Red List, a species must meet any of the following criteria (A–E) ("3G/10Y" signifies three generations or ten years—whichever is longer—over a maximum of 100 years; "MI" signifies Mature Individuals): The current extinction crisis is witnessing extinction rates that are occurring at a faster rate than that of the natural extinction rate. It has largely been credited towards human impacts on climate change and

392-433: The additional heat accelerates the ovulation in the females. At other times the species is generally not found on land. When on land, it is usually very shy and retreats to the water at the slightest hint of danger. The female lays an average of 75–123 eggs (average varies depending on region), which are placed during the night in a 60–80 cm (2.0–2.6 ft) deep nest that is dug on the beach. The eggs are laid during

420-405: The day. When nearing the breeding season, Arrau turtles migrate to certain sites where the eggs are laid. In some locations, nesting occurs in large groups on beaches, which reduces the risk posed by predators. Some beaches have as many as 500 nesting females. Mating occurs in the water. During and just before the nesting season the species frequently basks, typically in groups. It is suspected that

448-401: The exact color varies depending on the algae growing on the carapace. Adult Arrau turtles feed almost entirely on plant material such as fruits, seeds, leaves, legumes and algae, but may also take freshwater sponges , eggs and carcasses of dead animals (such as dead fish). Captives have been recorded feeding on meat. Juveniles feed on fish and plant material. The species is mainly active during

476-553: The largest individuals perhaps are as old as 80 years. The Arrau turtle is widespread and was not considered threatened overall by the IUCN in 1996 (the year of the last full review), but it has declined drastically, and a draft review by the IUCN Species Survival Commission —Tortoise and Freshwater Turtle Specialist Group in 2011 recommended that it should be considered critically endangered . The species

504-418: The low water season and hatch as the water starts to rise. If it rises too fast or too early, the nest is flooded and the young die within the eggs. As long as nests are not dug up by predators, the hatching success rate is usually high, averaging at 83%. The eggs hatch after about 50 days and the sex of the young depends on the nest temperature (females at higher temperatures, males at lower). When hatching,

532-404: The middle Orinoco River alone, it is estimated that as many as 330,000 nested in 1800, but less than half this number nested in 1945 and by the early 2000s (decade) it had fallen to 700–1300. In addition to hunting and collecting of their eggs, threats include pollution, habitat loss, and dams , which can cause flooding of nest sites. Several countries in their range have implemented laws protecting

560-493: The most dangerous period) and then released. All species in the genus Podocnemis are listed on CITES Appendix II . The slow growth limits its potential for major commercial turtle farming . Nevertheless, about 880,000 turtles of various species were kept at 92 farms (both ones that are commercial and ones with conservation purpose) in 2004 in Brazil alone, and some of these keep Arrau turtles, also in semi-intensive farm systems. Pleurodira The Pleurodira are one of

588-431: The neck is bent in the horizontal plane, drawing the head into a space in front of one of the front legs. A larger overhang of the carapace helps to protect the neck, which remains partially exposed after retraction. This differs from the method employed by a cryptodiran , which tucks its head and neck between its forelegs, within the shell. The different methods of bending the neck require completely different anatomies of

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616-482: The pterygoid. One of the three extant families in this suborder is the family Chelidae , which have a specially adapted strategy for catching prey. While the majority of the family Chelidae are omnivores, 17 species are carnivorous: Chelus fimbriatus and species of the Chelodina genus. This special strategy is referred to as a gape-suck mechanism. The turtle first opens its mouth little by little. Then, when

644-424: The public with information regarding the conservation status of animal, fungi, and plant species. It divides various species into seven different categories of conservation that are based on habitat range, population size, habitat, threats, etc. Each category represents a different level of global extinction risk. Species that are considered to be Critically Endangered are placed within the "Threatened" category. As

672-477: The skull. Another difference is in the arrangement of the bones of the shell and the scutes overlaying them. Pleurodiran turtles have 13 scutes on the plastron of the shell, whereas cryptodiran turtles have only 12. The extra scute is called the intergular and is at the front of the plastron between the gular scutes . Pelomedusid turtles also possess mesoplastra , further differentiating this group. The jaw closure mechanism has articulation on trochlear surfaces of

700-518: The species, but hunting and egg collection (even if illegal) continues. A number of conservation projects have been initiated. For example, 54 nesting beaches have been protected in Brazil, beaches used by more than 1,000 females are protected in Colombia, and since the mid-1990s many thousand eggs have been collected in Venezuela for safe incubation, the hatchlings "headstarted" (getting them through

728-523: The turtle is within striking range of the prey, it will open its mouth completely, sucking in water at such a rate that the current into its mouth is too strong for prey to escape and it engulfs the prey within 0.004 seconds. This strategy also circumvents issues to quick capture of underwater prey, such as resistance to rapid movement in water, pressure waves due to a rapid strike, and rapid water intake when feeding. After Ferreria, et al. 2018. Critically endangered The IUCN Red List provides

756-473: The two living suborders of turtles , the other being the Cryptodira . The division between these two suborders represents a very deep evolutionary divide between two very different types of turtles. The physical differences between them, although anatomical and largely internal, are nonetheless significant, and the zoogeographic implications of them are substantial. The Pleurodira are known more commonly as

784-422: The young are around 5 cm (2 in) long and dart directly for the water, but they emerge to the attentions of many predators so that only about five percent ever reach the adult feeding grounds. When hatching, the females emit sounds which attract the young; they stay together for a period in the flooded forests. Vocalizations appear to play an important role in the social life of this turtle and in addition to

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