A piranha or piraña (, , or ; or , ) is one of a number of freshwater

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Serrasalmidae, or the subfamily Serrasalminae within the tetra family,

Characidae Characidae, the characids or characins is a family of freshwater subtropical and tropical fish, belonging to the order Characiformes. The name "characins" is the historical one, but scientists today tend to prefer "characids" to reflect their ...

in order

Characiformes Characiformes is an order of ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, more than 2000 different species are described, including the well-known piranha and tetras.; Buckup P.A.: "Relationsh ...

. These fish inhabit South American rivers,

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

s, lakes and reservoirs. Although often described as extremely predatory and mainly feeding on fish, their dietary habits vary extensively, and they will also take plant material, leading to their classification as

omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...

Etymology

The name originates from the indigenous

Tupi people A subdivision of the Tupi-Guarani linguistic families, the Tupi people were one of the largest groups of indigenous Brazilians before its colonization. Scholars believe that while they first settled in the Amazon rainforest, from about 2,900 ...

and their respective

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 ...

. It is formed from two words, meaning fish and meaning tooth; the same word is used by Indians to describe a pair of scissors. Another possible derivation is from , probably literally "biting-fish". In the mid 18th century the Portuguese merged the word into . Finally, the word may also come from the combination of meaning fish and meaning cut (which also meant "bad" or "devil" in Tupi-Guarani).

Taxonomy and evolution

Piranhas belong to the subfamily Serrasalminae, which includes closely related omnivorous fish such as pacus. Traditionally, only the four genera '' Pristobrycon'', '' Pygocentrus'', '' Pygopristis'', and '' Serrasalmus'' are considered to be true piranhas, due to their specialized teeth. However, a recent analysis showed, if the piranha group is to be monophyletic, it should be restricted to ''Serrasalmus'', ''Pygocentrus'', and part of ''Pristobrycon'', or expanded to include these taxa plus ''Pygopristis'', ''

Catoprion ''Catoprion'' is a genus of serrasalmids from tropical South America, including the basins of the Amazon, Essequibo, Orinoco and Paraguay rivers. It was believed to be a monotypic In biology, a monotypic taxon is a taxonomic group (taxon) t ...

'', and '' Pristobrycon striolatus''. ''Pygopristis'' was found to be more closely related to ''Catoprion'' than the other three piranha genera. The total number of piranha species is unknown and contested, and new species continue to be described. Estimates range from fewer than 30 to more than 60.

Distribution

Piranhas are indigenous to the Amazon basin, in the Orinoco, in rivers of the Guianas, in the

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

– Paraná, and the São Francisco River systems, but there are major differences in the

species richness Species richness is the number of different species represented in an ecological community, landscape or region. Species richness is simply a count of species, and it does not take into account the abundances of the species or their relative ab ...

. In a review where 38–39 piranha species were recognized, 25 were from the Amazon and 16 from Orinoco, while only three were present in Paraguay–Paraná and two in São Francisco. Most species are restricted to a single river system, but some (such as the red-bellied piranha) occur in several. Many species can occur together; for example, seven are found in Caño Maporal, a stream in Venezuela. Aquarium piranhas have been unsuccessfully introduced into parts of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

. In many cases, however, reported captures of piranhas are misidentifications of pacu (e.g., red-bellied pacu or ''

Piaractus brachypomus ''Piaractus brachypomus'', the pirapitinga, is a large species of pacu, a close relative of piranhas and silver dollars, in the serrasalmid family.Nico, L.; P. Fuller; and M. Neilson (22 October 2013)Piaractus brachypomus.USGS Nonindigenous Aqua ...

'' is frequently misidentified as red-bellied piranha or '' Pygocentrus nattereri''). Piranhas have also been discovered in the Kaptai Lake in southeast

Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...

. Research is being carried out to establish how piranhas have moved to such distant corners of the world from their original habitat. Some rogue exotic fish traders are thought to have released them in the lake to avoid being caught by antipoaching forces. Piranhas were also spotted in the Lijiang River in China.

Description

Size

Depending on the exact species, most piranhas grow to between long. A few can grow larger, with the largest living species, the red-bellied, reaching up to . There are claims of São Francisco piranhas at up to , but the largest confirmed specimens are considerably smaller. The extinct ''

Megapiranha ''Megapiranha'' is an extinct serrasalmid characin fish from the Late Miocene (8–10 million years ago) Ituzaingó Formation of Argentina, described in 2009. The type species is ''M. paranensis''.dentition. All piranhas have a single row of sharp teeth in both jaws. The teeth are tightly packed and interlocking (via small cusps) and are used for rapid puncture and shearing. Individual teeth are typically broadly triangular, pointed, and blade-like (flat in profile). The variation in the number of cusps is minor. In most species, the teeth are tricuspid with a larger middle cusp which makes the individual teeth appear markedly triangular. The exception is ''Pygopristis'', which has pentacuspid teeth and a middle cusp usually only slightly larger than the other cusps.

Biting abilities

Piranhas have one of the strongest bites found in bony fishes. Relative to body mass, the black piranha (''Serrasalmus rhombeus'') produces one of the most forceful bites measured in vertebrates. This extremely powerful and dangerous bite is generated by large jaw muscles (adductor mandibulae) that are attached closely to the tip of the jaw, conferring the piranha with a mechanical advantage that favors force production over bite speed. Strong jaws combined with finely serrated teeth make them adept at tearing flesh.

Ecology

Close-up of a piranha at Georgia Aquarium

Piranhas vary extensively in ecology and behavior depending on exact species. Piranhas, especially the red-bellied (''Pygocentrus nattereri''), have a reputation as ferocious predators that hunt their prey in schools. Recent research, however, which "started off with the premise that they school as a means of cooperative hunting", discovered they are timid fish that schooled for protection from their own predators, such as cormorants,

caiman A caiman (also cayman as a variant spelling) is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family, the other being alligators. Caimans inhabit Mexico, Central and South America f ...

s, and

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 ...

s. Piranhas are "basically like regular fish with large teeth". A few other species may also occur in large groups, while the remaining are solitary or found in small groups. Although popularly described as highly predatory and primarily feeding on fish, piranha diets vary extensively, leading to their classification as

. In addition to fish (occasionally even their own species), documented food items for piranhas include other vertebrates (mammals, birds, reptiles), invertebrates (insects, crustaceans), fruits, seeds, leaves and detritus. The diet often shifts with age and size. Research on the species ''Serrasalmus'' aff. ''brandtii'' and ''Pygocentrus nattereri'' in Viana Lake in

Maranhão Maranhão () is a state in Brazil. Located in the country's Northeast Region, it has a population of about 7 million and an area of . Clockwise from north, it borders on the Atlantic Ocean for 2,243 km and the states of Piauí, Tocantins and ...

, which is formed during the wet season when the

Pindaré River The Pindaré River is a river in Maranhão state of north-central Brazil. 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 lef ...

(a tributary of the

Mearim River The Mearim River is a river in Maranhão state of northern Brazil. The river originates in the southern part of Maranhão, and drains north into the Baía de São Marcos, an estuary that also receives the Pindaré and Grajaú rivers, which are ...

) floods, has shown that they primarily feed on fish, but also eat vegetable matter. In another study of more than 250 ''Serrasalmus rhombeus'' at Ji-Paraná (Machado) River, 75% to 81% (depending on season) of the stomach content was fish, but about 10% was fruits or seeds. In a few species such as ''Serrasalmus serrulatus'', the dietary split may be more equal, but this is less certain as based on smaller samples: Among 24 ''S. serrulatus'' from flooded forests of Ji-Paraná (Machado) River, there were several with fish remains in their stomachs, but half contained masticated seeds and in most of these this was the dominant item. Piranhas will often

scavenge Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding b ...

, and some species such as ''Serrasalmus elongatus'' are specialized

scale-eater Lepidophagy is a specialised feeding behaviour in fish that involves eating the scales of other fish. Lepidophagy is widespread, having evolved independently in at least five freshwater families and seven marine families. A related feeding beh ...

s, feeding primarily on scales and fins of other fish. Scale- and fin-eating is more widespread among juvenile and sub-adult piranhas. Piranhas lay their eggs in pits dug during the breeding season and swim around to protect them. Newly hatched young feed on zooplankton, and eventually move on to small fish once large enough.

Relationship with humans

Piranha teeth are often used as tools themselves (such as for carving wood or cutting hair) or to modify other tools (such as sharpening of

darts Darts or dart-throwing is a competitive sport in which two or more players bare-handedly throw small sharp-pointed missiles known as darts at a round target known as a dartboard. Points can be scored by hitting specific marked areas of the bo ...

). This behavior has been documented among several South American tribes including the Camayura and

Shavante The Xavante (also Shavante, Chavante, Akuen, A'uwe, Akwe, Awen, or Akwen) are an indigenous peoples, indigenous people, comprising 15,315 individuals within the territory of eastern Mato Grosso state in Brazil. They speak the Xavante language, pa ...

in Brazil and the Pacahuara in Bolivia. Piranhas are also popular as food. They are often considered a nuisance by fishers since they steal bait, eat catches, damage fishing gear and may bite when accidentally caught. Piranhas can be bought as pets in some areas but they are illegal in many parts of the United States and in the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

where importers face six months to four years in jail and the piranhas destroyed to prevent proliferation in the latter. The most common aquarium piranha is ''Pygocentrus nattereri'', the

red-bellied piranha The red-bellied piranha, also known as the red piranha (''Pygocentrus nattereri''), is a Type (biology), type of piranha native to South America, found in the Amazon basin, Amazon, Paraguay River, Paraguay, Paraná River, Paraná and Essequibo Ri ...

. Piranhas can be bought fully grown or as young, often no larger than a thumbnail. It is important to keep ''Pygocentrus'' piranhas alone or in groups of four or more, not in pairs, since aggression among them is common, not allowing the weaker fish to survive, and is distributed more widely when kept in larger groups. It is not uncommon to find individual piranhas with one eye missing due to a previous attack.

Attacks

Although often described as extremely dangerous in the media, piranhas typically do not represent a serious risk to humans. However, attacks have occurred, especially when the piranhas are in a stressed situation such as the dense groups that may occur when the water is lower during the dry season and food is relatively scarce. Swimming near fishermen may increase the risk of attacks due to the commotion caused by struggling fish and the presence of bait in the water. Splashing attracts piranhas and for this reason children are more often attacked than adults. Being in the water when already injured or otherwise incapacitated also increases the risk. There are sometimes

warning sign A warning sign is a type of sign which indicates a potential hazard, obstacle, or condition requiring special attention. Some are traffic signs that indicate hazards on roads that may not be readily apparent to a driver. While warning traffi ...

s at high-risk locations and beaches in such areas are sometimes protected by a barrier. Most piranha attacks on humans only result in minor injuries, typically to the

feet The foot ( : feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made ...

or hands, but they are occasionally more serious and very rarely can be fatal. Near the city of Palmas in Brazil, 190 piranha attacks, all involving single bites to the feet, were reported in the first half of 2007 in an artificial lake which appeared after the

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use ...

ming of the

Tocantins River The Tocantins River ( pt, Rio Tocantins, link=no , , Parkatêjê: ''Pyti'' ɨˈti is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means " toucan's beak" (''Tukã'' for "toucan" and ''Ti'' for "beak ...

. In the state of

São Paulo São Paulo (, ; Portuguese for ' Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the Ga ...

, a series of attacks in 2009 in the

Tietê River The Tietê River ( Portuguese, Rio Tietê, ) is a Brazilian river in the state of São Paulo. The name Tietê was registered for the first time on a map published in 1748 by d’Anville. The name signifies "The truthful river", or "truthful w ...

resulted in minor injuries to 15 people. In 2011, another series of attacks at José de Freitas in the Brazilian state of Piauí resulted in 100 people being treated for bites to their toes or heels. On 25 December 2013, more than 70 bathers were attacked at Rosario in Argentina, causing injuries to their hands or feet.Mintz, Zoe (26 December 2013
Piranha Attack In Argentina Injures More Than 70, Fish Tore 'Bits Of Flesh' Off Swimmers On Christmas
ibtimes.com In 2011, a drunk 18-year-old man was attacked and killed in Rosario del Yata, Bolivia. In 2012, a five-year-old Brazilian girl was attacked and killed by a shoal of ''P. nattereri''. In February 2015, a six-year-old girl died after being attacked by piranhas when her grandmother's boat capsized during a vacation in

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 ...

. Whereas fatal attacks on humans are rare, piranhas will readily feed on bodies of people that already have died, such as drowning victims.

Reputation

Various stories exist about piranhas, such as how they can skeletonize a human body or

cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult ma ...

in seconds. These legends refer specifically to the

. A common falsehood is that they can be attracted by

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the cir ...

and are exclusively

carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other s ...

s. A Brazilian legend called "piranha cattle" states that they sweep the rivers at high speed and attack the first of the cattle entering the water allowing the rest of the group to traverse the river. These legends were dismissed through research by Hélder Queiroz and Anne Magurran and published in ''

Biology Letters ''Biology Letters'' is a peer-reviewed, biological, scientific journal published by the Royal Society. It focuses on the rapid publication of short high quality research articles, reviews and opinion pieces across the biological sciences. ''Biolog ...

''.

Theodore Roosevelt

When former US President

Theodore Roosevelt Theodore Roosevelt Jr. ( ; October 27, 1858 – January 6, 1919), often referred to as Teddy or by his initials, T. R., was an American politician, statesman, soldier, conservationist, naturalist, historian, and writer who served as the 26t ...

visited

in 1913, he went on a hunting expedition through the Amazon Rainforest. While standing on the bank of the Amazon River, he witnessed a spectacle created by local fishermen. After blocking off part of the river and starving the piranhas for several days, they pushed a cow into the water, where it was quickly torn apart and skeletonized by a school of hungry piranhas. Roosevelt later described piranhas as vicious creatures in his 1914 book '' Through the Brazilian Wilderness''.

References

External links

* {{curlie, Recreation/Pets/Fish_and_Aquaria/Freshwater/Species/Characins/Piranhas/ * Eric J. Lyman
"Piranha meat could take a bite out of what ails you"
''

Houston Chronicle The ''Houston Chronicle'' is the largest daily newspaper in Houston, Texas, United States. , it is the third-largest newspaper by Sunday circulation in the United States, behind only ''The New York Times'' and the ''Los Angeles Times''. With i ...

'', 17 July 1998
How to maintain healthy piranha in the home aquarium

"Piranha Feeding Frenzy"
National Geographic.com (2015-03-19) Fish common names Fish of South America Fish of the Amazon basin Fauna of the Pantanal Serrasalmidae Portuguese words and phrases