Natterer's Sägesalmler

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Natterer's Sägesalmler
Natterer's Sägesalmler (Pygocentrus nattereri)

Natterer's Sägesalmler ( Pygocentrus nattereri )

Systematics
Otophysa
Order : Tetras (Characiformes)
Family : Sägesalmler (Serrasalmidae)
without rank: Piranhas
Genre : Pygocentrus
Type : Natterer's Sägesalmler
Scientific name
Pygocentrus nattereri
Kner , 1858
A swarm of Natterers Sägesalmler in the tropical aquarium, Hagenbeck Zoo, Hamburg, Germany.
Inner jaw of a piranha ( Pygocentrus nattereri ). Description see Fish skull .
Typical head part of a Pygocentrus nattereri
Typical drawing of a red-bellied piranha with the red underside of the belly
Red-bellied piranha between plant roots
Young fish of Pygocentrus nattereri
Adult Natterer's Sägesalmler in the Prague Sea Aquarium
Natterer's Sägesalmler in the Prague Sea Aquarium

Natterer's Sägesalmler or red piranha ( Pygocentrus nattereri , syn . : Serrasalmus nattereri , Rooseveltiella nattereri ) is the most common piranha . It is named after the collector of the type specimens Johann Natterer . In Brazil, Pygocentrus nattereri is often called Piranha Vermelha or Piranha Caju because of its strong red belly color, and in Spanish-speaking countries it is usually just called Piraña. In German you can also find the term "Rotbäuchiger Piranha", a translation from the English Red-bellied Piranha .

distribution

The distribution area extends over the Amazon and Orinoco areas , Guayana and the Río de la Plata , Río Paraguay and the Río Paraná . It occurs in Venezuela , Colombia , Guiana, Ecuador , Peru , Brazil , Bolivia, Paraguay , Argentina and Uruguay . In the Brazilian Pantanal it occurs frequently in the rivers and periodically connected lakes and lagoons. It is also very common in rivers such as the Rio Negro and Rio Machado, which have high primary production .

Occurrences in the US states of Florida , Hawaii , Massachusetts , Michigan , Minnesota , Ohio , Oklahoma , Pennsylvania , Texas and Virginia are the result of stocking with animals from aquariums.

features

Natterer's Sägesalmler has the relatively high-backed and laterally compressed physique typical for its species. Elevation increases with age. It reaches a size of about 30 centimeters, with the males generally remaining smaller. The largest specimen to date was caught in the Río Cuiabá in the Pantanal in the Brazilian state of Mato Grosso do Sul . A specimen weighing 3.8 kilograms came from the Rio Xingu .

The bluish to brown-gray and strongly silvery shiny basic color is interrupted by metallic, glittering dots distributed over the whole body. The underside of the body is colored bright red. The dorsal fin is gray in color, the caudal fin is dark to black in color and has a light central part. The anal fin of juvenile fish is colored red, while adults also have a black border. During the spawning season, the overall color is significantly darker and the intensity of individual, metallic, shiny scales increases.

Natterer's Sägesalmler has 24 to 31 teeth on its belly keel .

Fin formula :

  • Dorsal II / 14-15
  • Anal III / 26-30
  • Pectorals 15-18

Way of life

nutrition

Recent studies by Magurran and Queiroz show that Pygocentrus natteri are predominantly omnivorous fish. The food spectrum of Natterer's Sägesalmler is diverse, it feeds on fish, carrion , insects , crabs , molluscs and also eats plant-based food. Smaller animals tend to look for food during the day, while medium-sized and large specimens prefer the twilight hours in the morning and in the evening until around 10:00 p.m. Hierarchies emerge within the groups.

Hunting out of dense vegetation is typical, groups of 20 to 30 specimens wait for potential prey in the protection of vegetation. This is usually attacked from behind or below after passing through the hideout. Attacks are often carried out by solitary animals, followed by one or two conspecifics. Occasionally, in response to sudden movements in the water, objects that have fallen into the water, or schools of fish that pass the lurking position, the whole group will leave cover. In addition to this attack tactic, the chase in open water also plays a role; it is often preceded by a waiting position in the vegetation.

When hunting for insects, molluscs and crustaceans, plants or the bottom of the water are examined visually for possible prey while the fish holds its position. Suitable food is then seized with a sudden forward movement ( English scan-and-pick tactic ).

Natterer's Sägesalmler always flocks together in swarms, which are less used to hunt prey than to protect against predators such as river dolphins , caimans and pirarucus . The merging in swarms significantly reduces the piranhas' stress behavior. If you separate an individual from the swarm, it shows clear fear behavior such as increased breathing and heart rate.

The swarms are inconsistent, while the larger adult specimens stay in the core of the swarm, the younger specimens are found on the outside and are constantly looking for prey. The need for conservation of the juvenile animals is higher than that of the adult animals, which is why they are much more active and snap at potential prey. Adult specimens have a higher chance of survival against attacks by predators in the middle of the swarm and feed on the remains of the young animals. If there is a feeding frenzy, the animals can sometimes injure each other. A remarkably fast wound healing in injured piranhas was observed.

In dry times, the schools, which are normally spread over a large body of water, are crowded together in a dense space in schools of 50, 100 or more fish and sometimes also predators, which increases their aggressiveness enormously.

Reproduction

Despite its comparatively wide distribution, the brood care behavior of Natterer's Sägesalmler is mainly known from observations of animals kept in aquariums. During courtship, males and females swim in small, opposing circles and, at the moment of the smallest distance, point their abdominal sides towards each other. With blows of the caudal fin and water jets from the mouth, a spawning pit 4 to 5 centimeters deep and about 15 centimeters in diameter is dug between plants. After a series of mock matings, the actual spawning takes place in the early hours of the morning, while the animals are trembling heavily and press their abdomen together. The male catches the falling eggs with his anal fin and then hurls them into the spawning pit. A clutch can contain up to 4000 of the yellow, approximately 1.5 millimeters large and extremely sticky eggs. The male takes care of the brood and drives away intruders, but potential threats outside the immediate vicinity of his own nest are not attacked. At 28 to 29 degrees Celsius, the larvae hatch after 3 to 4 days, another 3 days later they begin to swim freely and the sire ceases to care for the brood. In the Rio Miranda, a tributary of the Rio Paraguay, the reproduction of Pygocentrus nattereri has been observed in the wild. Schools of 20 to 25 sexually mature fish in sizes migrate to flooded grasslands at the beginning of the rainy season and spawn there. In the white water rivers and floodplain forests of the Mamirauá National Park near Tefé in the Brazilian state of Amazonas , it was found that Pygocentrus nattereri has two annual reproductive periods, which are dependent on the fluctuation of the water level and the flood momentum. The females produce up to 30,000 oocytes , but on average less than 1/3 of them mature. Sexual maturity begins in both sexes when they are around 160 millimeters tall. At this point in time, the sexually mature animals darken and temporarily lose their vivid coloring. While the animals spend the spawning process on flooded bank vegetation or flooded grassland, non-reproductive specimens prefer the open water.

Role in the ecosystem

Pygocentrus nattereri plays an important role as a predatory fish in the neotropical freshwater ecosystem of South America . During the spring tide Pororoca in the lower reaches of the Amazon and the resulting tidal wave, which spreads inland from the mouth, the water level can rise by up to 15 meters. The floods repeatedly lead to massive drowning of domestic and wild animals, which drift as cadavers on the waters and can lead to epidemics. Piranhas occupy the ecological niche as scavengers and are also referred to as "hyenas" or "vultures of freshwater" or "health police" because of this behavior. They specialize in eating dead, injured or sick animals, which they attack in small groups.

Systematics

Natterer's Sägesalmler was first described scientifically in 1858 by the Austrian zoologist Rudolf Kner . It belongs to the genus Pygocentrus , which includes the largest species of piranha. Due to its wide distribution, there are numerous color variants, local races and subspecies. Molecular biological data suggest that Pygocentrus nattereri is a collective species that consists of five separate lines with different distribution. These are the populations from the Amazon, as well as from the river basins of Rio Guaporé ( Terra typica ), Rio Itapecuru , Río Paraná and Rio Paraguay , and Rio Tocantins with Rio Araguaia .

Relationship with people

Use

Natterer's Sägesalmler is used locally as food fish, sport fish for anglers and aquarium fish. Piranha meat contains 8.2 percent fat , 15 percent animal protein and 4.4 percent minerals.

Natterer's Sägesalmler as a neozoon

Since the 1960s, deliberate or unintentional releases of piranha species such as Pygocentrus natteri and Serrasalmus rhombeus into wild waters of Florida, Alabama , Louisiana , Texas, Arizona and California have been observed in the southern states of the USA . Laboratory tests on the cold tolerance of Pygocentrus natteri have shown that water temperatures of 10 ° C are the critical lethal threshold for survival. If this temperature is not reached, no P. natteri population can exist. The species could survive in southern California, Texas, Florida and Hawaii as long as the minimum water temperatures are 14 ° C. The studies also showed that the activity and aggressiveness of the species increased with increasing water temperatures. At water temperatures below 14 ° C, the fish no longer showed any hunting behavior.

While attempts have been made in Bangladesh to keep Pygocentrus nattereri as a food fish in polycultures together with native fish, in southern India the fish is considered an invasive species that threatens the natural balance of the native fish fauna in some waters.

Attacks on people

P. nattereri is one of the species that can be dangerous to humans due to its aggressive behavior and large swarming. On December 7, 2011, a fisherman in the Bolivian Río Yata was so badly injured by a school of piranhas that he died of his wounds. The attack coincided with the spawning period of P. nattereri in this river. Ivan Sazima from the Universidade Estadual de Campinas and Sérgio de Andrade Guimarães from the hospital in Poconé investigated three cases between 1985 and 1986 in which human corpses were eaten by piranhas. The falls occurred in the São Lourenço river basin and near the city of Poconé in the Brazilian state of Mato Grosso . The erroneous assumption that piranhas attack humans is based on the observation that certain types of piranha eat human corpses, like other mammals. Sazima and Guimarães examined the bite patterns of the drowned people and came to the conclusion that there must be at least two differently sized piranha species which, as scavengers, caused certain wounds. Only the two species Pygocentrus nattereri and Serrasalmus spilopleura , which are very common and widespread in the Pantanal, were considered. It is known that both omnivorous species eat dead fish, birds and mammals in the water, sometimes even when they are severely decayed. P. nattereri is the larger species and has very strong teeth and jaws that allow them to bite open the thick layers of skin and firm flesh of mammals. In addition, P. nattereri occurs in larger swarms and thus usually represents the first scavenger on the prey. S. spilopleura with a smaller dentition detaches the P. natteri swarms and eats the remaining soft parts of the carcass.

Remarks

  1. ↑ On the etymology of the generic names: pygocentrus (Greek) " Stingelsteiß " (cf. Centropyge ) similar to Serrasalmus (Latin) "Sägesalmler" refer to saw-like sharp abdominal scales. Theodore Roosevelt was a promoter of expeditions.
  2. ↑ Trans. Red Piranha
  3. ↑ after the intensely red cashew fruit
  4. ^ River in the Brazilian state of Rondônia
  5. ^ Anne Magurran, Population Biologist, St. Andrews University, Scotland
  6. ↑ Hélder Queiroz, Instituto de Desenvolvimento Sustentável Mamirauá, Brazil
  7. ↑ " two annual reproductive seasons, tuned to water level fluctuation and the flooding pulse "
  8. ^ Tributary of the Río Paraguay , flows through the Pantanal and borders on Bolivia, Paraguay and Brazil

swell

literature

  • Ivan Sazima, Francisco A. Machado: Underwater observations of piranhas in western Brazil , Environmental Biology of Fishes 28, pp. 17–31, 1990, ISSN  0378-1909 (print), ISSN  1573-5133 (online)
  • Massao Uetanabaro, Tobias Wang, August S. Abe: Breeding behavior of the red-bellied piranha, Pygocentrus nattereri, in nature , Environmental Biology of Fishes 38, pp. 369-371, 1993, ISSN  0378-1909 (print), ISSN  1573 -5133 (online)
  • Axel Zarske: Pygocentrus natteri Kner, (1860). In: Claus Schaefer, Torsten Schröer (Hrsg.): The large lexicon of aquaristics. Eugen Ulmer, Stuttgart 2004, ISBN 3-8001-7497-9 , p. 841.
  • Günther Sterba : The world's freshwater fish. 2nd Edition. Urania, Leipzig / Jena / Berlin 1990, ISBN 3-332-00109-4 .
  • HL Queiroz, MB Sobanski, AE Magurran: Reproductive strategies of Red-bellied Piranha (Pygocentrus nattereri Kner, 1858) in the white waters of the Mamiraua flooded forest, central Brazilian Amazon , Environmental Biology of Fishes 2010, Vol. 89, no.1 , pp. 11-19.
  • HL Queiroz, AE Magurran: Safety in Numbers? Shoaling behavior of the Amazonian red-bellied piranha . Biological Letters of the Royal Society, 2005, Vol. 1, n. 2, 155-157.

Web links

Commons : Natterers Sägesalmler  - Collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e Pygocentrus nattereri summary page. In: fishbase.sinica.edu.tw. Retrieved May 3, 2019 .
  2. ↑ Michael Corniff: Piranhas - unrecognized robbers. In: geo.de. Retrieved May 3, 2019 .
  3. ↑ Pygocentrus nattereri. In: www.jjphoto.dk. Archived from the original on March 10, 2011 ; accessed on May 3, 2019 .
  4. ^ HL Queiroz, AE Magurran: Safety in Numbers? Shoaling behavior of the Amazonian red-bellied piranha . In: Biological Letters of the Royal Society . tape 1 , June 22, 2005, p. 155–157 , doi : 10.1098 / rsbl.2004.0267 (English).
  5. ↑ Dagny Lüdemann: Piranhas - actually very nice. In: tagesspiegel.de. July 3, 2007, accessed May 3, 2019 .
  6. ↑ Massao Uetanabaro, Tobias Wang, Augusto S. Abe: Breeding behavior of the red-bellied piranha, Pygocentrus nattereri in nature . In: Environmental Biology of Fishes . No. 38 , 1993, pp. 369-371 ( springer.com ).
  7. ↑ HL Queiroz, MB Sobanski, AE Magurran: Reproductive strategies of Red-bellied Piranha (Pygocentrus nattereri Kner, 1858) in the white waters of the Mamiraua flooded forest, central Brazilian Amazon . In: Environmental Biology of Fishes . tape 89 , no. 1 , 2010, p. 11-19 (English).
  8. ↑ Lucélia Nobre Carvalho, Rafael Arruda, Kleber Del-Claro: Host-parasite interactions between the piranha Pygocentrus nattereri (Characiformes: Characidae) and isopods and branchiurans (Crustacea) in the Rio Araguaia basin, Brazil . In: Neotropical Ichthyology . tape 2 , no. 2 , 2004, p. 93–98 (English, scielo.br [PDF; 200 kB ]).
  9. ↑ Jonas Klereborn: Where Piranhas live. In: www.sysf.physto.se. May 2000, archived from the original on November 30, 2014 ; accessed on May 3, 2019 .
  10. ↑ Wolfgang Schulte: Piranhas. Interesting facts about ecology, behavior, care and breeding, In: Lehrmeister-Bücherei 3rd, revised edition, Landbuch Hannover 1995, pp. 48–53, ISBN 3-7842-1114-3 .
  11. ↑ Mateussi, NTB, Melo, BF, Foresti, F. & Oliveira, C. (2019): Molecular Data Reveal Multiple Lineages in Piranhas of the Genus Pygocentrus (Teleostei, Characiformes). Genes, 10 (5): 371. doi: 10.3390 / genes10050371 .
  12. ↑ Wayne A. Bennett, Rebecca J. Currie, Paul Wagner, Thomas Beitinger: Cold Tolerance and Potential Overwintering of the Red-Bellied Piranha Pygocentrus nattereri in the United States . In: Transactions of the American Fisheries Society . No. 126 , 1997, pp. 841-849 , doi : 10.1577 / 1548-8659 (1997) 126 <0841: CTAPOO> 2.3.CO; 2 (English).
  13. ^ Cold Tolerance of Pygocentrus nattereri, Page 1. In: angelfire.com. Oregon Piranha Exotic Fish Exhibit, Sutherlin, Oregon, December 5, 2015, accessed May 3, 2019 .
  14. ↑ MM Rahman, AT Abu Ahmed, MM Mahmud, MA Hossain: Growth Study of an exotic fish, Red Piranha (Pygocentrus nattereri) in Polyculture . In: Int. J. Sustain. Crop Prod . tape 3 , no. 2 , 2008, p. 33–38 (English, cabi.org [PDF; 108 kB ]).
  15. ↑ JD Marcus Knight: Invasive ornamental fish: a potential threat to aquatic biodiversity in peninsular India ( PDF file ( Memento from November 1, 2012 in the Internet Archive ); 149 kB).
  16. ↑ Oregon Piranha Exotic Fish Exibit.
  17. ↑ Teenager killed by piranha ( Memento from April 7, 2014 in the Internet Archive )
  18. ↑ Teen Commits Suicide by Jumping Into School of Piranhas
  19. ↑ Nightmare Piranha Attack Leaves a Bolivia Teenager Dead ( Memento from April 7, 2014 in the Internet Archive )
  20. ↑ Ivan Sazima, Sérgio de Andrade Guimarães: Scavenging on human corpses as a source for stories about man-eating piranhas . In: Environmental Biology of Fishes . tape 20 , no. 1 , September 1987, pp. 75-77 , doi : 10.1007 / BF00002027 .