| 1 | Beni anaconda |
One of 4 anaconda species currently recognized, the Beni anaconda (Eunectes beniensis) is exclusive to northern Bolivia. This species was originally believed to be a hybrid of the green anaconda and yellow anaconda, but was declared independent in 2002. Beni anacondas are a massively powerful constrictor which reach a maximum length of 4.4 metres. They favour swamps, shallow creeks and seasonally flooded grassland, while avoiding dense upland forest habitats.
Beni anacondas are known by locals as sicurí, and are far more active during rainy season, grinding almost to a complete halt during dry season. The best way to find a Beni anaconda is wading through waist deep water, crouching down to shuffle through overhanging vegetation, and poking thick shoreline vegetation with a stick, until flushing one out.
In January 2010, scientists captured a female Beni anaconda measuring 220cm in a rice field, in its namesake Beni Department, Bolivia. It immediately regurgitated a 192cm male Beni anaconda, only slightly shorter than its own body. Cannibalism isn’t extremely rare in the snake kingdom, but Beni anacondas take it to giant new proportions.
Beni anacondas are still a controversial species, as a 2024 paper argued that they likely belong to the yellow anaconda (Euneces noteus), which mainly inhabits Paraguay. A point in favour of independence was that the two are divided by several hundred miles, with no point of contact, but the two only had shallow genetic divergence in preliminary tests.
| 2 | Erythrolamprus dorsocorallinus |
This species lives in Peru, extreme western Brazil, and a huge swathe of Bolivia. Erythrolamprus dorsocorallinus averages at 50-60cm, and possesses only a mild venom.
Erythrolamprus dorsocorallinus are often caught near marshes within primary rainforests, and crossing foot trails within rainforests. They can also be found on well-vegetated lake shores, and moist grassland. Moisture is a must for Erythrolamprus dorsocorallinus; you’ll never find them in parched arid lands. This snake also likes to climb stems and rest on massive rainforest leaves.
This species preys on amphibians, with two confirmed species being the brown egg frog and Chaco granulated toad. The latter is normally lethal, riddled with poisonous bufotoxins, proving that this snake has inbuilt resistance.
Erythrolamprus dorsocorallinus has mainly bright yellow scales, each with a slight black tip at the edges. The resulting effect is like a thin black net has been cast over their body. However, rare individuals from Bolivia have blue shades as well, intermingling with the yellow. Scientists have noticed how all this fades to grey rapidly post death and preservation.
| 3 | Southern sharpnose snake |
An elusive species found only in the densest lowland rainforests. Southern sharpnose snakes are pure rainforest spawn, and are easily recognizable by their juicy green base overlaid with a bark grey spine. This species is nearly always found resting on low jungle foliage like broad leaves or stems.
Southern sharpnose snakes prey primarily on lizards, with some frogs. Until 2020, they were part of the large Philodryas family, and known as Philodryas georgeboulengeri. However, its elongated snout and sharpened face were so blatantly different that it was separated into the Xenoxybelis family, which has one other member: the striped sharpnose snake (Xenoxybelis argenteus).
Southern sharpnose snakes appear in rainforest, usually at low elevations. In a 2019 study, the percentage thickness of canopy cover had a close correlation with their abundance. They were especially sensitive to elevation, and disappeared completely from more mountainous spots. Of the two Xenoxybelis members, southern sharpnose snakes were found to be significantly less flexible in their habitats. Finding this snake is an achievement, whether in Bolivia or Peru.
| 4 | Linnaeus’ sipo |
An extremely widespread species in South America, including Bolivia, where they inhabit virtually the entire country. Linnaeus’ sipos (Chironius exoletus) are completely non-venomous, though will gape their mouth wide and make sudden jabbing strikes if cornered. At a maximum of 154.5cm, this is one of Bolivia’s longer snakes.
Linnaeus’ sipo correlates closely with forests, but is flexible about the exact type. They’re been found in rainforests, cloud forests, riverside gallery forests, and forest edges alike.
Their diet consists mainly of frogs, especially treefrogs, with endless species being confirmed, including red snouted treefrogs, Canelos tree frogs, and upper Amazon tree frogs. They can also eat lizards, birds, and Nauta salamanders as potential backups. The only prey they never eat is mammals, possibly because the local anacondas and pitvipers have muscled in on this niche first. In 2008, Linnaeus’ sipos were discovered to eat the poisonous Porto Alegre golden-eyed tree frog (which is a long name), showing that they have toxin resistance.
Linnaeus’ sipos have large eyes with round pupils, and move mainly by day. At night, they sleep on branches up to 8 metres above ground.
| 5 | Amazon coastal house snake |
An orange to pale grey species, which is widespread across South America. Amazon coastal house snakes (Thamnodynates pallidus) measure 50cm and are nearly always found near water. They associate with small pools within rainforests, which they lurk above on branches 1 metre high, perhaps to use as a vantage point to scan for frogs below.
Thamnodynastes pallidus range from sea level to 2000 metres. They’re regarded as extremely aggressive, biting and snapping the moment they’re gripped (which we can’t blame them for). Once their fangs sink in, they can be very difficult to detach. In 2003, a man required 40 seconds and outside assistance to remove an Amazon coastal house snake from his finger. The bite began to swell slightly, which spread and achieved its peak at 35 minutes. The man also experienced excessive saliva with a metallic taste, and a strong headache. The swelling disappeared at 36 hours post bite.
This was the first detailed bite report for Thamnodynastes pallidus, and pain and heat were said to radiate from the bite site. Amazon coastal house snakes aren’t capable of ruining your life, but possibly your day or week.
| 6 | Steinbach’s snake |
An ultra rare snake which is the sole member of its Baliodryas family. Steinbach’s snakes are found in lowland rainforests of the far western Amazon, particularly Bolivia.
Barely anything is known about Steinbach’s snake. They have relatively dull colours, consisting of alternating brown-grey parallel stripes. The exception is their head, which has three pairs of white blotches. They appear to stick to tangled rainforest floors rather than resting on branches, weaving through the undergrowth maze stealthily.
The picture above shows that frogs or toads are one of their confirmed prey. Steinbach’s snake was originally collected in Bolivia in the early 20th century, by José Steinbach and his son Francisco, over 25 years from 1903 to 1928. Most of these were near the city of Santa Maria in Bolivia’s Buena Vista province.
As of 2021, this snake was known only from 14 individuals. Rainforests are a treacherous, unwelcoming place for any scientist to explore, no matter how matter how trained with a machete. Cars are virtually useless, and venomous pitvipers could be hanging from any branch. Luckily, Steinbach’s snakes aren’t venomous as far as we know, just highly elusive.
| 7 | Cutlass |
A nonvenomous yet aggressive species which reaches a maximum of 180.6cm. The cutlass (Phrynonax sexcarinatus) appears both on branches and the vegetated rainforest floor. Likewise, they’re found in forests, but also relatively open areas with abundant sun exposure. The cutlass moves by day, while at night, they sleep on branch perches 1.8-3.5 metres high.
While incapable of dealing out death, they have an aggressive defensive display. A cornered cutlass (even if accidentally cornered) while throw their upper half into a sudden S-shape, before inflating their neck grotesquely. They then produce a sharp hiss before attacking the interloper with their sharp fangs.
Cutlasses are variable in appearance, as some individuals are tree bark grey overlaid with occasional brown bands, while others are slimy green (like above). Rather than frogs or lizards, the cutlass preys mainly on birds, similarly to its puffing snake relatives in central America. Juveniles meanwhile, feast on grasshoppers, moths and beetles, and likely other rainforest insects.
The cutlass is widespread in South America, ranging from Bolivia at the southern end, to Colombia in the north. This species isn’t blind; if you walk past them on a branch, they’ll know that you’re there, and it would be wisest to keep on walking.
| 8 | Catesby’s snail-eater |
An epically colored snake. For reasons unknown, Catesby’s snail eater (Dipsas catesbyi) has evolved a brick red base overlaid with black circles like lumps of coal, each with a messy snowy white border. This species inhabits a huge swathe of South America, including Bolivia, and reaches a maximum of just 72.6cm. Its bulging eyes are another ID sign, similarly to its fellow Dipsas snail eaters (the family has over 30 members).
This species is so light and thin that it can rest on even the flimsiest rainforest leaf, while soaked in rainwater. In an untouched world, Catesby’s snail eater would be a rainforest species, but they’re flexible enough to inhabit disturbed forests, banana plantations, and rural gardens. Household cats occasionally kill them, while Catesby’s snail eater in turn hunts not only snails, but slugs and soft-bodied insects.
A flustered Catesby’s snail eater will coil into a tight ball. Bites from this species are not just rare, but virtually unheard of. This species has minor variation in patterns, as the black circles are occasionally larger and push the red and white back, creating a blacker appearance overall. They overlap in Bolivia with the Bolivian snail eater (Dipsas turgida), but this species has a more black and white appearance, and the dark blotches are far messier rather than circular.
| 9 | Boa constrictor |
The boa constrictor is one of Earth’s most successful snakes, covering virtually all of South America. As ever, they’re one of the most regularly sighted snakes in Bolivia. However, southeast Bolivia hosts a specific form called Boa constrictor amarali, sometimes called the Bolivian short-tailed boa. This has unusual silver tones and a shorter tail, and is relatively small at 1.2-1.8 metres.
This silver form is much sought after in captivity, though relatively rare due to Bolivia fully banning the export of native snakes. Several observations have been made of this possible subspecies, like a boa that died after swallowing a tree porcupine and being punctured by its spines.
Whether Boa constrictor amarali is actually a subspecies has been doubted lately. A 2024 study found only minor genetic separation between it and Boa constrictor constrictor, by far the most common subspecies (the classic beige-black one). What’s certain is that Bolivia hosts an unusual amount of silver individuals. The 2024 study also discovered that boa constrictors along Brazil’s Atlantic coast near Rio de Janeiro were actually an independent species, which they named Boa atlantica, adding yet another new species to the 3900 snakes worldwide.
| 10 | Chlorosoma laticeps |
A heavily arboreal snake which is nearly always spotted on low branches, whether the thick arms of trees or thin and spindly fingers. Chlorosoma laticeps knows exactly how to manage its weight distribution to prevent themselves falling to the forest floor.
Despite regularly exceeding 1 metre, this is one South America’s more mysterious snakes. Chlorosoma laticeps seems to have a large range, as it has sightings in Bolivia and southwest Brazil, but also a handful of sightings along Brazil’s Atlantic coast thousands of miles away. Either their territory has two massively separated pockets, or its numbers are so sparse that even scientists rarely sight them.
This species belongs to the 3-member Chlorosoma family, but is unique due to its oily black inner mouth. Elsewhere, the greenness spreads to their eyes, which have round pupils. Occasionally, Chlorosoma laticeps is one of the few blue snakes on earth, with a rare morph combining aqua blue with the usual green flanks.
Chlorosoma laticeps is a venomous species, with an abundance of metalloproteinases. There’s also a smattering of neurotoxic three finger toxins (less than 2% of toxins), similarly to coral snakes. However, the exact potency in humans is unknown.