The tucuxi (''Sotalia fluviatilis''), alternatively known in
Peru
, image_flag = Flag of Peru.svg
, image_coat = Escudo nacional del Perú.svg
, other_symbol = Great Seal of the State
, other_symbol_type = National seal
, national_motto = "Firm and Happy f ...
''bufeo gris'' or ''bufeo negro'', is a species of freshwater
dolphin
A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the ...
found in the rivers of the
Amazon basin. The word ''tucuxi'' is derived from the
Tupi language
Old Tupi, Ancient Tupi or Classical Tupi (also spelled as Tupí) is an extinct Tupian language which was spoken by the aboriginal Tupi people of Brazil, mostly those who inhabited coastal regions in South and Southeast Brazil. It belongs to ...
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 dolphin
River dolphins are a polyphyletic group of fully aquatic mammals that reside exclusively in freshwater or brackish water. They are an informal grouping of dolphins, which itself is a paraphyletic group within the infraorder Cetacea. Extant riv ...
s such as the
boto
Boto is a Portuguese name given to several types of dolphins and river dolphins native to the Amazon and the Orinoco River tributaries. A few botos exist exclusively in fresh water, and these are often considered primitive dolphins.
Classificatio ...
, the tucuxi is not closely related to them genetically. Instead, it is classed in the
oceanic dolphin
Oceanic dolphins or Delphinidae are a widely distributed family of dolphins that live in the sea. Close to forty extant species are recognised. They include several big species whose common names contain "whale" rather than "dolphin", such as the ...
family (Delphinidae).
Physically, the species resembles the
bottlenose dolphins, but differs sufficiently to be placed in a separate
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
, ''
Sotalia
The dolphin genus ''Sotalia'' is considered to have two member species with the classification of '' Sotalia guianensis'' as a distinct species from '' Sotalia fluviatilis'' in 2007. This was a result of recent morphometric analyses, as well as m ...
''. The
Guiana dolphin
The Guiana dolphin (''Sotalia guianensis''), also known as the estuarine dolphin or costero, is a dolphin found in the coastal waters to the north and east of South America, and east of Central America. It is a member of the oceanic dolphin fami ...
(''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.
Description
The tucuxi is frequently described (see references below) as looking similar to 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
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
region is much lighter, often pinkish. It is theorized that this pinkish color may be caused or intensified by increased blood flow. The
dorsal
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
* Dorsal c ...
fluke is typically slightly hooked. The beak is well-defined and of moderate length. There are 26 to 36 pairs of teeth in the upper and lower jaws. The tucuxi has one of the largest known
encephalization quotient
Encephalization quotient (EQ), encephalization level (EL), or just encephalization is a relative brain size measure that is defined as the ratio between observed to predicted brain mass for an animal of a given size, based on nonlinear regress ...
s among mammals.
Taxonomy
The tucuxi (''Sotalia fluviatilis'') was described by
Gervais and
Deville in 1853, and the
costero
The Guiana dolphin (''Sotalia guianensis''), also known as the estuarine dolphin or costero, is a dolphin found in the coastal waters to the north and east of South America, and east of Central America. It is a member of the oceanic dolphin fami ...
(''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 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.
Distribution
The tucuxi exists along much of the length of the
Amazon River and many of its tributaries, and is found in
Venezuela
Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...
,
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
,
Peru
, image_flag = Flag of Peru.svg
, image_coat = Escudo nacional del Perú.svg
, other_symbol = Great Seal of the State
, other_symbol_type = National seal
, national_motto = "Firm and Happy f ...
,
Ecuador
Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ' ...
, southeastern
Colombia. Numerous individuals have been seen in the
Orinoco River
The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers , with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the wor ...
further north, though it is not clear whether these are tucuxi or
costero
The Guiana dolphin (''Sotalia guianensis''), also known as the estuarine dolphin or costero, is a dolphin found in the coastal waters to the north and east of South America, and east of Central America. It is a member of the oceanic dolphin fami ...
. 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 the Amazon basin. This species occurs in freshwater habitats only.
Food and foraging
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.
[
]
Behaviour
The tucuxi exists in small groups of about 10-15 individuals, and swim in tight-knit groups, suggesting 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 was 36 years of age.[
]
Threats
Medicinal use
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.
Magic and religious use
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 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.
Fishing
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 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.
Habitat Degradation and Loss
The tucuxi's habitat has been greatly affected by anthropogenic activities including the expansion of hydroelectric projects, which usually results in isolation where 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.
Conservation
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
Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
due to gold mining
Gold mining is the extraction of gold resources by mining. Historically, mining gold from alluvial deposits used manual separation processes, such as gold panning. However, with the expansion of gold mining to ores that are not on the surface, ...
, 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
A zoo (short for zoological garden; also called an animal park or menagerie) is a facility in which animals are kept within enclosures for public exhibition and often bred for conservation purposes.
The term ''zoological garden'' refers to zoo ...
of Münster
Münster (; nds, Mönster) is an independent city (''Kreisfreie Stadt'') in North Rhine-Westphalia, Germany. It is in the northern part of the state and is considered to be the cultural centre of the Westphalia region. It is also a state di ...
, Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
.
The tucuxi is listed on Appendix II[Appendix II]
" of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5 March 2009
/ref> of the Convention on the Conservation of Migratory Species of Wild Animals (CMS
CMS may refer to:
Computing
* Call management system
* CMS-2 (programming language), used by the United States Navy
* Code Morphing Software, a technology used by Transmeta
* Collection management system for a museum collection
* Color manag ...
). It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
See also
*List of cetaceans
Cetacea is an infraorder that comprises the 94 species of whales, dolphins, and porpoises. It is divided into toothed whales (Odontoceti) and baleen whales (Mysticeti), which diverged from each other in the Eocene some 50 million years ago (m ...
* Environmental issues in Brazil
References
*''National Audubon Society Guide to Marine Mammals of the World''
*''Encyclopedia of Marine Mammals''
*''Whales, Dolphins and Porpoises'', Mark Carwardine,
External links
Whale and Dolphin Conservation Society (WDCS)
{{Taxonbar , from=Q935680
Oceanic dolphins
Mammals of South America
Mammals of Brazil
Mammals of Peru
Mammals described in 1853
Taxa named by Émile Deville