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30-724: The Pindaré rises in the low hills which separate its basin from that of the Tocantins River to the south. In its lower reaches it is called the Pindaré-Mirim. It is a left tributary of the Mearim River , which it joins not far from that river's mouth in the Baía de São Marcos . The Serra do Tiracambu lies to the west, and separates the basin of the Pindaré from that of the Gurupí River . Part of

60-581: A connection with the Paraná and São Francisco rivers . The Tocantins and these two rivers flow in different directions, but all have their source in the Brazilian Plateau in a region where a low watershed allows some exchange between them. There are several fish species that migrate along the Tocantins to spawn, but this has been restricted by the dams. Following the construction of the massive Tucuruí Dam ,

90-528: A dam is built. Pollution from human activity has also degraded the quality of the habitat and increases the chance for tucuxis to consume heavy metals. The tucuxi is endemic to the regions described above; although no precise estimates of population are available, it is common. A significant human problem is fishing nets. Deliberate hunting in the Amazon basin for food has also been reported. Pollution, in particular, mercury poisoning of water due to gold mining ,

120-420: A high richness of fish species, although it is relatively low by Amazon basin standards. More than 350 fish species have been registered, including more than 175 endemics . The most species rich families are Characidae (tetras and allies), Loricariidae (pleco catfish and allies) and Rivulidae (South American killifish). While most species essentially are of Amazonian origin, there are also some showing

150-406: A highly developed social structure. Tucuxis are quite active and may jump clear of the water (a behavior known as breaching), somersault, spy-hop or tail-splash. They are unlikely, however, to approach boats. Tucuxis have been observed to feed with other river dolphins. They feed on a wide variety of fish. Studies of growth layers suggest the species can live up to 35 years . The oldest known animal

180-505: A point about 160 km (99 mi) above its junction with the Tocantins, it saws its way across a rocky dyke for 20 km (12 mi) in roaring cataracts. Two other tributaries, called the Maranhão and Paranatinga , collect an immense volume of water from the highlands which surround them, especially on the south and south-east. Between the latter and the confluence with the Araguaia,

210-495: Is a particular concern for this species. The IUCN also cites habitat fragmentation by dam construction as a threat, though more detailed study is necessary. Tucuxis are observed not to maintain good health and attitude in captive environments. A few tucuxis remained in captivity in European aquaria, but the last one ("Paco") died in 2009 in the Zoo of Münster , Germany . The tucuxi

240-550: Is a species of freshwater dolphin found in the rivers of the Amazon basin . The word tucuxi is derived from the Tupi language word tuchuchi-ana , and has now been adopted as the species' common name. Despite being found in geographic locations similar to those of 'true' river dolphins such as the boto , the tucuxi is not closely related to them genetically. Instead, it is classed in the oceanic dolphin family (Delphinidae). Physically,

270-665: Is the only known cave-adapted knifefish and one of only two known non-catfish in caves of the South American mainland (the other is the characid Stygichthys typhlops ). In its lower reaches, the Tocantins separates the Tocantins–Araguaia–Maranhão moist forests ecoregion to the east from the Xingu–Tocantins–Araguaia moist forests ecoregion to the west. It acts as a barrier that prevents dispersal of flora and fauna between these ecoregions. Downstream from

300-650: The Araguaia River , has its extreme southern headwaters on the slopes of the Serra dos Caiapós . The Araguaia flows 1,670 km (1,040 mi) before its confluence with the Tocantins, to which it is almost equal in volume. Besides its main tributary, the Rio das Mortes , the Araguaia has twenty smaller branches, offering many miles of canoe navigation. In finding its way to the lowlands, it breaks frequently into waterfalls and rapids , or winds violently through rocky gorges, until, at

330-443: The Amazon basin. This species occurs in freshwater habitats only. Tucuxis forage in tight groups, often chasing fish in rapid dashes just below the water surface, with fish jumping out of their way. Thirty species of fish are known to be prey, some living in protected lakes and channels, while others occur in fast-flowing rivers. The tucuxi exists in small groups of about 10-15 individuals, and swim in tight-knit groups, suggesting

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360-593: The Amazon proper. It flows through four Brazilian states ( Goiás , Tocantins , Maranhão , and Pará ) and gives its name to one of Brazil's newest states, formed in 1988 from what was until then the northern portion of Goiás . The Tocantins is one of the largest clearwater rivers in South America. It rises in the mountainous district known as the Pireneus , west of the Federal District, but its western tributary,

390-508: The Araguaia confluence, in the state of Pará, the river used to have many cataracts and rapids, but they were flooded in the early 1980s by the artificial lake created by the Tucuruí Dam , one of the world's largest. When the second phase of the Tucuruí project was completed on November 30, 2010, a system of locks called Eclusas do Tucuruí was established with the goal of making a long extension of

420-407: The Tocantins is occasionally obstructed by rocky barriers which cross it almost at a right angle. The Tocantins basin (which includes the Araguaia River ) is the home of several large aquatic mammals such as Amazonian manatee , Araguaian river dolphin and tucuxi , and larger reptiles such as black caiman , spectacled caiman and yellow-spotted river turtle . The Tocantins River Basin has

450-402: The area. They are particularly vulnerable to entanglement in commercial fishing nets in the lower Japurá River . The carcasses of the dolphins caught incidentally or intentionally are often used as bait for piracatinga fishing. The tucuxi's habitat has been greatly affected by anthropogenic activities including the expansion of hydroelectric projects, which usually results in isolation where

480-437: The bottlenose dolphin, but it is typically smaller at around 1.5 m (4.9 ft). The dolphin is colored light to bluish grey on its back and sides. The ventral region is much lighter, often pinkish. It is theorized that this pinkish color may be caused or intensified by increased blood flow. The dorsal fluke is typically slightly hooked. The beak is well-defined and of moderate length. There are 26 to 36 pairs of teeth in

510-572: The country. In the Tupi language , its name means " toucan 's beak" ( Tukã for "toucan" and Ti for "beak"). It runs from south to north for about 2,450 km (1,520 mi). While sometimes included in definitions of the Amazon basin, the Tocantins is not a branch of the Amazon River , since its waters flow into the Atlantic Ocean via an eastern channel of the Amazon Delta , alongside those of

540-588: The flow of the river changed. Some species have been adversely affected and there has been a substantial reduction in species richness in parts of the river. The São Domingos karst in the upper Tocantins basin is home to an unusually high number of cavefish species (more than any other region in the Americas): Ancistrus cryptophthalmus , several Ituglanis species, Pimelodella spelaea , Aspidoras mephisto , an undescribed Cetopsorhamdia species and Eigenmannia vicentespelaea . The last

570-465: The following specific discharge rates: Tocantins (11 L/s/km or 1.0 cu ft/s/sq mi), Araguaia (16 L/s/km or 1.5 cu ft/s/sq mi), Pará (17 L/s/km or 1.6 cu ft/s/sq mi) and Guamá (21 L/s/km or 1.9 cu ft/s/sq mi). Tucuxi The tucuxi ( Sotalia fluviatilis ), alternatively known in Peru bufeo gris or bufeo negro ,

600-555: The length of the Amazon River and many of its tributaries, and is found in Venezuela , Brazil , Peru , Ecuador , and southeastern Colombia . Numerous individuals have been seen in the Orinoco River further north, though it is not clear whether these are tucuxi or costero . The tucuxi has recently been found to inhabit a larger range, including the northeast portion of Brazil such as the state of Amapa, which includes more basins than

630-419: The margins of the great sandstone plateaus, from 300 to 600 metres (980 to 1,970 ft) elevation above sea-level, through which the rivers have eroded their deep beds. Around the estuary of the Tocantins the great plateau has disappeared, having been replaced by a part of the forest-covered, half submerged alluvial plain , which extends far to the north-east and west. The Pará River , generally called one of

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660-502: The mouths of the Amazon, is only the lower reach of the Tocantins. If any portion of the waters of the Amazon runs round the southern side of the large island of Marajó into the river Para, it is only through tortuous, natural canals, which are in no sense outflow channels of the Amazon. The Tocantins River records a mean discharge rate of 13,598 m /s (480,200 cu ft/s) and a specific discharge rate of 14.4 L/s/km (1.32 cu ft/s/sq mi). The sub-basins have

690-465: The river navigable. In total there are seven dams on the river ( Serra da Mesa dam , Cana Brava dam, São Salvador dam, Peixe Angical dam, Luiz Eduardo Magalhães (Lajeado) dam, Estreito dam, and Tucuruí dam), of which the largest are the Tucuruí and the Serra da Mesa dam. The flat, broad valleys, composed of sand and clay, of both the Tocantins and its Araguaia branch are overlooked by steep bluffs. They are

720-445: The river's basin lies in the 271,197 hectares (670,140 acres) Gurupi Biological Reserve , a full protected conservation unit created in 1988. Average annual rainfall is 2,169 millimetres (85.4 in). Temperatures range from 22 to 32 °C (72 to 90 °F) with an average of 27 °C (81 °F). The Pindaré basin is home to tropical moist broadleaf forest , and the river divides the Tocantins–Araguaia–Maranhão moist forests to

750-415: The species resembles the bottlenose dolphins , but differs sufficiently to be placed in a separate genus , Sotalia . The Guiana dolphin ( Sotalia guianensis ), a related dolphin present in coastal and estuarine environments and formerly grouped together with the tucuxi, have recently been recognized as a distinct species. The tucuxi is frequently described (see references below) as looking similar to

780-473: The upper and lower jaws. The tucuxi has one of the largest known encephalization quotients among mammals. The tucuxi ( Sotalia fluviatilis ) was described by Gervais and Deville in 1853, and the costero ( Sotalia guianensis ) by Pierre-Joseph van Bénéden in 1864. These two species were subsequently synonymized, with the two species being treated as subspecies of marine and freshwater varieties. The first to reassert differences between these two species

810-483: The water. Other products such as perfumes and powders made with the genital organs are sold as aphrodisiacs. The number of dolphins harvested for magical or religious purposes and its effect on tucuxi populations is unknown. Interactions of tucuxi dolphins with fishing activity is common in the Western Brazilian Amazon. Tucuxi forage on schooling fish that are also important species for commercial fishing in

840-512: The west from the Maranhão Babaçu forests to the east. This article related to a river in Maranhão , Brazil is a stub . You can help Misplaced Pages by expanding it . Tocantins River The Tocantins River (Portuguese: Rio Tocantins Portuguese pronunciation: [ˈʁi.u tokɐ̃ˈtʃĩs, tu-] , Parkatêjê : Pyti [pɨˈti]) is a river in Brazil , the central fluvial artery of

870-576: Was 36 years of age. The oil and fat in the skin of tucuxi is used in local traditional medicine as an ointment to be rubbed on wounds or sore body parts. The ointment is thought to treat illnesses such as hemorrhoids, rheumatism, and arthritis, while the teeth are used in a powder form to treat asthma. The eyes, teeth, and genital organs of tucuxi are sold throughout Northern Brazil as magical charms that promote good luck, love, and financial rewards. Baths are also created with these body parts and are meant to help one attract sexual partners if they bathed in

900-457: Was a three-dimensional morphometric study of Monteiro-Filho and colleagues. Subsequently, a molecular analysis by Cunha and colleagues unambiguously demonstrated that Sotalia guianensis was genetically differentiated from Sotalia fluviatilis . This finding was reiterated by Caballero and colleagues with a larger number of genes. The existence of two species has been generally accepted by the scientific community. The tucuxi exists along much of

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