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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.<ref name="ITIS">{{#if:209577 | {{#invoke:template wrapper|wrap|_template=cite web|_exclude=id,ID,taxon
| url = https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=209577 | title = Eunectes | publisher = Integrated Taxonomic Information System }}
| Template:Citation error }}</ref><ref name="NRDB">Template:NRDB species</ref><ref name=rivas>Template:Cite journal</ref>
DescriptionEdit
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),Template:Cn which is the largest snake in the world by weight, and the second longest after the reticulated python.Template:Cn
OriginEdit
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.<ref>Template:Cite journal</ref> Fossils of recent ancestors are not known, so the living species 'pull' the historical range of the genus to the present.
EtymologyEdit
The name Eunectes is derived from Template:Langx.
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 {{#invoke:Lang|lang}} (1693) as {{#invoke:Lang|lang}}.<ref>Template:Cite book</ref>
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.<ref>Template:Cite book</ref> 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.Template:Efn
Yule and Frank Wall noted that the snake was a python and suggested a Tamil origin Template:Transliteration meaning elephant killer.<ref>Template:Cite book</ref> A Sinhalese origin was also suggested by Donald Ferguson who pointed out that the word Template:Transliteration (Template:Transliteration lightning/large and Template:Transliteration stem/trunk) was used in Sri Lanka for the small whip snake (Ahaetulla pulverulenta)<ref>Template:Cite journal</ref> and somehow got misapplied to the python before myths were created.<ref>Template:Cite journal</ref><ref>Template:Cite book</ref><ref>Template:Cite book</ref>
The name commonly used for the anaconda in Brazil is sucuri, sucuriju or sucuriuba.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Distribution and habitatEdit
Found in tropical South America from Ecuador, Brazil, Colombia and Venezuela south to Argentina.<ref name="McD99"/>
FeedingEdit
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 young jaguars<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> that venture too close to the water.
Relationship with humansEdit
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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
SpeciesEdit
| Species | Taxon author | Common name | Geographic range | Image | |
|---|---|---|---|---|---|
| E. akayima | Rivas et al., 2024<ref name=rivas /> | Northern green anaconda | Ecuador, Colombia, Venezuela, Trinidad, Guyana, Suriname, French Guiana, and northern Brazil<ref name=natgeo /> | ||
| E. beniensis (=E. notaeus?) | Dirksen, 2002<ref>Template:Cite book</ref> | Bolivian anaconda | South America in the Departments of Beni and Pando in Bolivia | ||
| E. deschauenseei (=E. notaeus?) | Dunn and Conant, 1936<ref name="ITIS"/> | Dark-spotted anaconda | South America in northern Brazil and coastal French Guiana<ref name="McD99"/> | ||
| E. murinus | (Linnaeus, 1758)<ref name="ITIS"/> | Green anaconda | citation | CitationClass=web
}}</ref> |
|
| E. notaeus | Cope, 1862<ref name="ITIS"/> | Yellow anaconda | South America in eastern Bolivia, central-western Brazil, Paraguay and northeastern Argentina<ref name="McD99"/> | ||
| †E. stirtoni | Hoffstetter and Rage, 1977<ref>Template:Cite journal</ref> | This species is extinct; its fossils have been found in the La Venta fauna (Miocene) in Colombia. Its validity, however, is questionable. |
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Rivas et al.<ref name="rivas" /> 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: Template:Clade 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.<ref>Template:Cite journal</ref>
Mating systemEdit
The mating seasons in Eunectes varies both between species and within species depending on locality, although the trend appears to be the dry season.<ref name="ReedRodda">Template:Cite book</ref><ref name=Pizzatto>Template:Cite journal</ref> 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.<ref name="ReedRodda" />
Sexual dimorphismEdit
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 Template:Convert and males average only around Template:Convert.<ref name="Pizzatto" /><ref name="Rivas_etal_2007">Template:Cite book</ref> 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.<ref name="Rivas2001">Template:Cite journal</ref> 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.<ref name="Rivas2001" /> 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.<ref name="Rivas2001" />
Breeding ballsEdit
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.<ref name="Rivas_etal_2007" /><ref name="Rivas2001" /><ref name="Waller2007">Template:Cite book</ref><ref name="Rivas2005">Template:Cite journal</ref> 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.<ref name="Rivas_etal_2007" /> 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.<ref name="Rivas_etal_2007" /> 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.<ref name="Rivas_etal_2007" /><ref name="Rivas2001" />
Sexual cannibalismEdit
Cannibalism is quite easy in anacondas since females are so much larger than males, but sexual cannibalism has only been confirmed in E. murinus.<ref name="Quintana">Template:Cite journal</ref> 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.<ref name="ReedRodda" /><ref name="Quintana" />
Asexual reproductionEdit
Although sexual reproduction is by far the most common in Eunectes, E. murinus has been observed to undergo facultative parthenogenesis.<ref name="ReedRodda" /><ref name="Shibata">Template:Cite journal</ref> 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 mythologyEdit
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.<ref>As visões da anaconda: a narrativa escrita indígena no Brasil. Template:Webarchive Por Lynn Mario T. Menezes de Souza. Revista Semear n°7</ref><ref>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.</ref><ref>Template:Cite periodical</ref>
See alsoEdit
- Jaguar, a competitor or predator
NotesEdit
ReferencesEdit
Further readingEdit
External linksEdit
- {{#invoke:citation/CS1|citation
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