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Temporal range: Miocene–recent[1]
Green anaconda (E. murinus)
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Boidae
Subfamily: Boinae
Genus: Eunectes
Wagler, 1830[2]
Type species
Boa murina
Range of Eunectes

Anacondas or water boas are a group of large boas of the genus Eunectes. They are a semiaquatic group of snakes found in tropical South America. Three to five extant and one extinct species are currently recognized, including one of the largest snakes in the world, E. murinus, the green anaconda.[3][4][5]


Although the name applies to a group of snakes, it is often used to refer only to one species, in particular, the common or green anaconda (Eunectes murinus),[citation needed] which is the largest snake in the world by weight, and the second longest after the reticulated python.[citation needed]


The recent fossil record of Eunectes is relatively sparse compared to other vertebrates and other genera of snakes. The fossil record of this group is effected by an artifact called the Pull of the Recent.[6] Fossils of recent ancestors are not known, so the living species 'pull' the historical range of the genus to the present.


An anaconda skeleton at the Redpath Museum

The name Eunectes is derived from Ancient Greek: εὐνήκτης, romanizedeunēktēs, lit.'good swimmer'.

The South American names anacauchoa and anacaona were suggested in an account by Peter Martyr d'Anghiera. The idea of a South American origin was questioned by Henry Walter Bates who, in his travels in South America, failed to find any similar name in use. The word anaconda is derived from the name of a snake from Ceylon (Sri Lanka) that John Ray described in Latin in his Synopsis Methodica Animalium (1693) as serpens indicus bubalinus anacandaia zeylonibus, ides bubalorum aliorumque jumentorum membra conterens.[7]

Ray used a catalogue of snakes from the Leyden museum supplied by Dr. Tancred Robinson. The description of its habit was based on Andreas Cleyer, who in 1684 described a gigantic snake that crushed large animals by coiling around their bodies and crushing their bones.[8] Henry Yule in his 1886 work Hobson-Jobson, notes that the word became more popular due to a piece of fiction published in 1768 in the Scots Magazine by a certain R. Edwin. Edwin described a 'tiger' being crushed to death by an anaconda, when there were never any tigers in Sri Lanka.[a]

Yule and Frank Wall noted that the snake was a python and suggested a Tamil origin anai-kondra meaning elephant killer.[10] A Sinhalese origin was also suggested by Donald Ferguson who pointed out that the word Henakandaya (hena lightning/large and kanda stem/trunk) was used in Sri Lanka for the small whip snake (Ahaetulla pulverulenta)[11] and somehow got misapplied to the python before myths were created.[12][13][14]

The name commonly used for the anaconda in Brazil is sucuri, sucuriju or sucuriuba.[15]

A 4.3-metre (14 ft) anaconda skeleton (center) on display at the Museum of Osteology, alongside other species for comparison

Distribution and habitat

Found in tropical South America from Ecuador, Brazil, Colombia and Venezuela south to Argentina.[2]


All five species are aquatic snakes that prey on other aquatic animals, including fish, river fowl, and caiman. Videos exist of anacondas preying on domestic animals such as goats and sometimes even jaguars[16] that venture too close to the water.

Relationship with humans

While encounters between people and anacondas may be dangerous, they do not regularly hunt humans. Nevertheless, threat from anacondas is a familiar trope in comics, movies, and adventure stories (often published in pulp magazines or adventure magazines) set in the Amazon jungle. Local communities and some European explorers have given accounts of giant anacondas, legendary snakes of much greater proportion than any confirmed specimen.

Although charismatic, there is little known on the biology of wild anacondas. Most of our knowledge comes from the work of Dr. Jesús A. Rivas and his team working in the Venezuelan Llanos.[17]


Species Taxon author Common name Geographic range Image
E. akayima Rivas et al., 2024[5] Northern green anaconda Ecuador, Colombia, Venezuela, Trinidad, Guyana, Suriname, French Guiana, and northern Brazil[18]
E. beniensis (=E. notaeus?) Dirksen, 2002[19] Bolivian anaconda South America in the Departments of Beni and Pando in Bolivia
E. deschauenseei (=E. notaeus?) Dunn and Conant, 1936[3] Dark-spotted anaconda South America in northern Brazil and coastal French Guiana[2]
E. murinus (Linnaeus, 1758)[3] Green anaconda Peru, Bolivia, French Guiana, Suriname and Brazil[18]
E. notaeus Cope, 1862[3] Yellow anaconda South America in eastern Bolivia, central-western Brazil, Paraguay and northeastern Argentina[2]
E. stirtoni Hoffstetter and Rage, 1977[20] This species is extinct; its fossils have been found in the La Venta fauna (Miocene) in Colombia. Its validity, however, is questionable.

Rivas et al.[5] revised the taxonomy of Eunectes, describing a new species of green anaconda (Eunectes akayima) and merging E. deschauenseei and E. beniensis with E. notaeus, which resulted in the recognition of only three species of anaconda. The result of their phylogenetic analysis is represented below:

Green anacondas
Eunectes notaeus

Eunectes notaeus

Eunectes notaeus

In a response paper, Dubois et al. questioned the results of the mtDNA analysis above and the validity of Eunectes akayima. The name of the new species was considered a nomen nudum.[21]

Mating system

Eunectes murinus[dubious ] in Colombia

The mating seasons in Eunectes varies both between species and within species depending on locality, although the trend appears to be the dry season.[22][23] The green anaconda (E. murinus) is the most well-studied species of Eunectes in terms of their mating system, followed by the yellow anaconda (E. notaeus); unfortunately E. deschauenseei and E. beniensis are much less common, making the specific details of their mating systems less well understood.[22]

Sexual dimorphism

Sexual size dimorphism in Eunectes is the opposite of most other vertebrates. Females are larger than males in most snakes, and green anacondas (E. murinus) have one of the most extreme size differences, where females average roughly 32 kg (70 lb) and males average only around 7 kg (15 lb).[23][24] This size difference has several benefits for both sexes. Large size in females leads to higher fecundity and larger offspring; as a result male mate choice favours larger females.[25] Large size is also favoured in males because larger males tend to be more successful at reproducing, both because of their size advantage in endurance rivalry and their advantage in sperm competition because larger males are able to produce more sperm.[25] One reason that males are so much smaller in Eunectes is that large males can be confused for females, which interferes with their ability to mate when smaller males mistakenly coil them in breeding balls; as a result, there is an optimum size for males where they are large enough to successfully compete, but not large enough to risk other males trying to mate with them.[25]

Breeding balls

During the mating season female anacondas release pheromones to attract males for breeding, which can result in polyandrous breeding balls; these breeding balls have been observed in E. murinus, E. notaeus, and E. deschauenseei, and likely also occur in E. beniensis.[24][25][26][27] In the green anaconda (E. murinus), up to 13 males have been observed in a breeding ball, which have been recorded to last two weeks on average.[24] In anaconda breeding balls, several males coil around one female and attempt to position themselves as close to her cloaca as possible where they use their pelvic spurs to "tickle" and encourage her to allow penetration.[24] Since there are often many males present and only one male can mate with the female at a time, the success of a male often depends on his persistence and endurance, because physical combat is not a part of the Eunectes mating ritual, apart from firmly pushing against other males in an attempt to secure the best position on the female.[24][25]

Sexual cannibalism

4.5-metre (14 ft) green anaconda skeleton on display at Museum of Osteology with other squamates and reptiles.

Cannibalism is quite easy in anacondas since females are so much larger than males, but sexual cannibalism has only been confirmed in E. murinus.[28] Females gain the direct benefit of a post-copulatory high-protein meal when they consume their mates, along with the indirect benefit of additional resources to use for the formation of offspring; cannibalism in general (outside of the breeding season) has been confirmed in all but E. deschauenseei, although it is likely that it occurs in all Eunectes species.[22][28]

Asexual reproduction

Although sexual reproduction is by far the most common in Eunectes, E. murinus has been observed to undergo facultative parthenogenesis.[22][29] In both cases, the females had lived in isolation from other anacondas for over eight years, and DNA analysis showed that the few fully formed offspring were genetically identical to the mothers; although this is not commonly observed, it is likely possible in all species of Eunectes and several other species of Boidae.

Indigenous mythology

According to the founding myth of the Huni Kuin, a man named Yube fell in love with an anaconda woman and was turned into an anaconda as well. He began to live with her in the deep world of waters. In this world, Yube discovered a hallucinogenic drink with healing powers and access to knowledge. One day, without telling his anaconda wife, Yube decided to return to the land of men and resume his old human form. The myth also explains the origin of cipó or ayahuasca — a hallucinogenic drink taken ritualistically by the Huni Kuin.[30][31][32]

See also

  • Jaguar, a competitor or predator


  1. ^ In South Asian languages like Hindi, the leopard and tiger may share the same name, that is Bágh (Hindi: बाघ), and it is the former that occurs in Sri Lanka.[9]


  1. ^ Hsiou, Annie S.; Albino, Adriana M. (1 December 2009). "Presence of the genus Eunectes (Serpentes, Boidae) in the Neogene of Southwestern Amazonia, Brazil". Journal of Herpetology. 43 (4): 612–619. doi:10.1670/08-295.1. S2CID 55097666.
  2. ^ a b c d e McDiarmid, R. W.; Campbell, J. A.; Toure, T. (1999). Snake Species of the World: A Taxonomic and Geographic Reference. Vol. 1. Washington, District of Columbia: Herpetologists' League. ISBN 1-893777-01-4.
  3. ^ a b c d "Eunectes". Integrated Taxonomic Information System. Retrieved 18 July 2008.
  4. ^ Eunectes beniensis at the Reptile Database. Accessed 12 December 2008.
  5. ^ a b c Rivas, Jesús; De La Quintana, Paola; Mancuso, Marco; Pacheco, Luis; Rivas, Gilson; Mariotto, Sandra; Salazar-Valenzuela, David; Tepeña Baihua, Marcelo; Baihua, Penti; Burghardt, Gordon; Vonk, Freek; Hernandez, Emil; García-Pérez, Juán Elías; Fry, Bryan; Corey-Rivas, Sarah (16 February 2024). "Disentangling the Anacondas: Revealing a New Green Species and Rethinking Yellows". Diversity. 16(2) (127): 127. doi:10.3390/d16020127.
  6. ^ Sahney, Sarda; Benton, Michael (2017). "The impact of the Pull of the Recent on the fossil record of tetrapods" (PDF). Evolutionary Ecology Research. 18: 7–23.
  7. ^ Ray, John (1693). Synopsis methodica animalium quadrupedum et serpentini generis (in Latin). London: Impensis S. Smith & B. Walford. p. 332. doi:10.5962/bhl.title.41459 – via Biodiversity Heritage Library.
  8. ^ Owen, Charles (1742). An essay towards a natural history of serpents. London. p. 114. doi:10.5962/bhl.title.58688 – via Biodiversity Heritage Library.
  9. ^ Pocock, Reginald I. (1930). "The Panthers and Ounces of Asia". Journal of the Bombay Natural History Society. 34 (2): 307–336 – via Biodiversity Heritage Library.
  10. ^ Wall, Frank (1921). Ophidia Taprobanica or the Snakes of Ceylon. Ceylon: H. R. Cottle, Government Printer. p. 48. doi:10.5962/bhl.title.53694 – via Biodiversity Heritage Library.
  11. ^ Willey, Arthur (1904). "Some rare snakes of Ceylon". Spolia Zeylanica. 1 (3): 81–89 – via Internet Archive.
  12. ^ Ferguson, Donald (1897). "The derivation of "Anaconda"". Notes and Queries. 12 (294): 123–124. doi:10.1093/nq/s8-XII.294.123 – via Internet Archive.
  13. ^ Skeat, Walter W. (1882). A concise etymological dictionary of the English Language. Oxford University Press. p. 16 – via Internet Archive.
  14. ^ Yule, Henry; Burnell, Arthur C. (1903). Hobson-Jobson. London: John Murray. pp. 24–25 – via Internet Archive.
  15. ^ "Dicionário online de português: sucuriju" (in Portuguese). Retrieved 19 February 2014.
  16. ^ Rivas, Jesús. "Frequently Asked Questions". Archived from the original on 21 December 2016. Retrieved 30 July 2012.
  17. ^ Rivas, Jesús. "Life history and conservation of the green anaconda (Eunectes murinus)". Archived from the original on 6 March 2018. Retrieved 30 July 2012.
  18. ^ a b Jason Bittel (16 February 2024). "The world's heaviest snake has been hiding a big secret". National Geographic.
  19. ^ Dirksen, Lutz (2002). Anakondas. Monographische Revision der Gattung Eunectes (Wagler, 1830) (in German). Münster: Natur und Tier-Verlag. ISBN 3-931587-43-6.
  20. ^ Hoffstetter, R.; Rage, J. C. (1977). "Le gisement de vertébrés miocènes de La Venta (Colombie) et sa faune de serpents". Annales de Paléontologie (Vertébrés) (in French). 63: 161–190.
  21. ^ Dubois, Alain; Denzer, Wolfgang; Entiauspe-Neto, Omar M.; Frétey, Thierry; Ohler, Annemarie; Bauer, Aaron M.; Pyron, R. Alexander (15 March 2024). "Nomenclatural problems raised by the recent description of a new anaconda species (Squamata, Serpentes, Boidae), with a nomenclatural review of the genus Eunectes". Bionomina. 37 (1): 8–58. doi:10.11646/bionomina.37.1.2. ISSN 1179-7657.
  22. ^ a b c d Reed, Robert N.; Rodda, Gordon H. (2009). Giant constrictors: Biological and management profiles and an establishment risk assessment for nine large species of pythons, anacondas, and the boa constrictor. U.S. Geological Survey Open-File Report 2009-1202. Reston, Virginia: U.S. Geological Survey.
  23. ^ a b Pizzatto, Lígia; Marques, Otavio A. V. (2007). "Reproductive ecology of Boine snakes with emphasis on Brazilian species and a comparison to Pythons". South American Journal of Herpetology. 2 (2): 107–122. doi:10.2994/1808-9798(2007)2[107:reobsw];2. S2CID 86033920.
  24. ^ a b c d e Rivas, Jesús A.; Muñoz, M. C.; Burghardt, G. M.; Thorbjarnarson, J. B. (2007). "Sexual size dimorphism and the mating system of the green anaconda (Eunectes murinus)". In Henderson, Robert W.; Powell, Robert (eds.). Biology of the Boas and Pythons. Eagle Mountain, Utah: Eagle Mountain Publishing. pp. 461–473. ISBN 978-0-9720154-3-1.
  25. ^ a b c d e Rivas, Jesús A.; Burghardt, Gordon M. (2001). "Understanding sexual size dimorphism in snakes: wearing the snake's shoes". Animal Behaviour. 62 (3): F1–F6. doi:10.1006/anbe.2001.1755. S2CID 5374924.
  26. ^ Waller, T.; Micucci, P. A.; Alvarenga, E. (2007). "Conservation biology of the yellow anaconda (Eunectes notaeus) in Northeastern Argentina". In Henderson, Robert W.; Powell, Robert (eds.). Biology of the Boas and Pythons. Eagle Mountain, Utah: Eagle Mountain Publishing. pp. 340–362. ISBN 978-0-9720154-3-1.
  27. ^ Rivas, Jesús A.; Burghardt, Gordon M. (2005). "Snake mating systems, behavior, and evolution: The revisionary implications of recent findings". Journal of Comparative Psychology. 119 (4): 447–454. doi:10.1037/0735-7036.119.4.447. PMID 16366778.
  28. ^ a b De la Quintana, Paola; Pacheco, Luis; Rivas, Jesús (January 2011). "Eunectes beniensis (Beni Anaconda). Diet: Cannibalism". Herpetological Review. 42 (4): 614.
  29. ^ Shibata, Hiroki; Sakata, Shuichi; Hirano, Yuzo; Nitasaka, Eiji; Sakabe, Ai (2017). "Facultative parthenogenesis validated by DNA analyses in the green anaconda (Eunectes murinus)". PLOS ONE. 12 (12): e0189654. Bibcode:2017PLoSO..1289654S. doi:10.1371/journal.pone.0189654. PMC 5728508. PMID 29236745.
  30. ^ As visões da anaconda: a narrativa escrita indígena no Brasil. Por Lynn Mario T. Menezes de Souza. Revista Semear n°7
  31. ^ O que nos diz a arte Kaxinawa sobre a relação entre identidade e alteridade? Por Elsje Maria Lagrou. Mana vol. 8 n°1 Rio de Janeiro abril de 2002 ISSN 0104-9313.
  32. ^ Eliane Camargo (1999). "Yube, o homem-sucuriju: Relato caxinauá" (PDF). Amerindia (in Portuguese). No. 24. Archived from the original (PDF) on 31 January 2005. Retrieved 17 June 2018.

Further reading

External links

  • The dictionary definition of anaconda at Wiktionary