Added 27 June 2002. Last updated 9 May 2008: updated Introduction, added Taxonomic Note re E. barbouri, added E. beniensis, added further details to E. murinus, updated Bibliography and corrected Links.

A quick guide to BOAS:



Genera Eunectes

Anacondas are among the most enigmatic and renowned of snakes, having a ferocious reputation that is not without foundation. At the same time they are somewhat secretive, and this and their often inaccessible habitat means that we know less about them than we do about the other giant constrictors. Their size has often been exaggerated: average Green Anacondas grow to 15-25', while the largest specimen accurately recorded was in excess of 30'. Measuring shed skins is supposedly not a wholly reliable guide to size since the shed skin is stretched in the act of shedding. Nevertheless the myth of, or belief in, an as yet unfound giant reaching greater lengths remains popular, as evidenced by the Anaconda films.

The genus is found only in South America from Venezuela and Colombia to Argentina, in riverine and oxbow habitats. Their primarily aquatic nature is emphasised by the position of the eyes towards the top of the head. In the Amazon the Green Anaconda is the most common species of the genus.

While these snakes are undoubtedly fascinating and beautiful, three factors combine to make them a less than sensible choice for most keepers. The first is their potential size, at least in the case of the Green Anaconda, not only in terms of length but also of girth. The second is their predilection for watery habitats, which with such large snakes would necessitate at least a bath-sized receptacle of water in the case of the Green Anaconda. The third and potentially most important is their temperament, which is rarely docile. Bartlett suggests that an unaccompanied individual should be wary of approaching individuals of about 8' or over. Yellow Anacondas are obviously rather smaller but offer a similar challenge, at least in terms of habitat and temperament.

Taxonomic Note

The species E. barbouri was formerly considered distinct by virtue of pale-centred rings (rather than black spots) on its back. Strimple et al in Journal of Herpetology 31:4 (possibly issue 33:4) showed that these were in fact variants in populations of otherwise normal Green Anacondas, E. murinus, and that furthermore there were degrees of spot development.

Yellow Anaconda, Eunectes notaeus, in Rotterdam Zoo April 2005. The anaconda was active in the water but appeared undisturbed by people close to the glass. Copyright N R Smith 2005.

Species Common Name Origin Adult size Notes
E. beniensis   Bolivia ?' Described by Dirksen in 2002: see TIGR database entry for information.
E. deschauenseei Dark-Spotted/ Deschauense's Anaconda NE Brazil, French Guiana ?' Limited distribution: no other information available.
E. murinus Green Anaconda Venezuela, Colombia, Brazil, N Bolivia, NE Peru, Guyana, Trinidad Avg up to 15': max 25-30' In terms of weight and general size this is the largest snake in the world, although the Reticulated Python P. reticulatus may occasionally be longer in length. The Green Anaconda is also one of the most irascible constrictors, and this combined with its sheer size and power make it a very unwise pet of choice for the vast majority of herpetoculturists. Temperament notwithstanding, a would-be keeper should take into consideration the amount of space required to keep such a giant, and the fact that it is primarily aquatic and would therefore need a large body of water to make it feel truly at home. In the wild the Green Anaconda eats a variety of vertebrate prey including fish, amphibians, other reptiles (including the fierce caimans) and mammals. In common with other large constrictors, after a large meal the snake may not then need to eat for weeks or even months. Although mainly water dwellers they are also capable of climbing trees. Rumours abound of even large specimens in the tropical rainforests, but so far these have been unproven. See the TIGR database entry for information and some good links. Coloration: overall ground colour varies from olive drab to olive green, darkest dorsally, becoming paler laterally to a light olive. Coloration of invididuals is variable, with darkness of coloration apparently dependent upon temperature and time of day, colder individuals appearing darker but perhaps unusually daytime colours appearing darker than at night. Paired or alternating black oval spots run from the neck to the tip of the tail, and dark edged peach spots are visible ventrolaterally. Peach spots lacking dark edging are found on the neck. The top of the head is darker than the sides. A black stripe runs diagonally downwards from the eye to a point behind the head. Reproduction: usually 8-35 young born, but over 50 per litter have also been recorded. [SOURCE: Bartlett & Bartlett].
E. notaeus Yellow Anaconda Bolivia, Paraguay, Uruguay, W Brazil, NE Argentina 8-12' Smaller but still fierce species: females tend to be larger. The Yellow Anaconda preys largely on birds, rodents and caimans (see the Anaconda Web Page). Herpetoculturists can and have kept this species successfully, but again the prospective keeper should beware that they have similar requirements and similar temperaments to their larger relatives.


Boas: A Complete Pet Owner's Manual, Doug Wagner, Barrons, 1996, New York/Hong Kong. Excellent book covering all the boas, including the obscure species unlikely to be seen. Highly recommended.

Snakes: A Complete Pet Owner's Manual, R D & P Bartlett, Barrons, 1997, New York/Hong Kong. Covers snakes in general but has a good section on the more popular and available boas.

Snakes of the World, Chris Mattison, Blandford, 1986/1992, London. A good book with the only reservation being that applied to Dieter Schmidt's, ie some of the taxonomy/classification is now out of date. See also Mattison's Keeping and Breeding Snakes (Blandford) which is probably more immediately useful to snake keepers.

Reptiles and Amphibians of the Amazon: An Ecotourist's Guide, R D and Patricia Bartlett.

"R&A Quicks", Reptile Hobbyist 3:7. Briefly summarises the article by Strimple et al re E. barbouri.

I have not read it myself, but Anacondas by Lutz Dirksen (Natur und Tier Verlag, Münster, 190pp, 2002) offers an overview of the genus.


The Boidae (Boas and Pythons) section of the TIGR reptile database provided (as always) much useful information, especially regarding subspecies, distributions and the history of recent taxonomic changes.

A good site to visit is the Anaconda Web Page.


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