What began as a routine genetics survey in Ecuador’s rainforest has now surfaced as gripping, never-before-seen footage: the exact moment researchers and Indigenous guides came face to face with a huge snake that would later be confirmed as part of a newly recognised species of giant anaconda.
A tense encounter on a remote Amazon river
The scene unfolds in the Baihuaeri Waorani Territory, a stretch of the Ecuadorian Amazon normally far from television cameras. In 2022, a small scientific team was there to collect DNA samples from anacondas. Actor Will Smith joined them with a National Geographic crew filming the series “Pole to Pole with Will Smith.”
Venom specialist Professor Bryan Fry from the University of Queensland sat in a narrow wooden boat beside Waorani guides, scanning the muddy banks for tell-tale ripples. The water was opaque, the light dim under the canopy, and rain hung in the air.
Scientists and Waorani guides suddenly spotted a massive, olive-green body sliding through a gap in the riverside vegetation.
The guides steered the boat into a small clearing. There, coiled half in the shallows and half on land, lay a vast female anaconda — Fry later estimated her at around 16 to 17 feet (4.9 to 5.2 metres) long.
Pinning a predator that kills by crushing
The footage shows the Waorani guides moving first, feet sinking into the mud as they approach the snake with calm precision. One grabs the head, another secures the thick, muscular body. Will Smith and Fry wade in once the animal is pinned, staying clear of the coils that can kill by crushing.
Green anacondas are non-venomous constrictors. They seize prey with their jaws, then loop their bodies around it and squeeze. Blood flow to the heart stops, and the animal suffocates. For a snake this size, a struggling human is not an easy meal, but a bite could still be serious — and those coils are nothing to underestimate.
While the guides hold the anaconda steady, Fry and Smith carefully snip a small section of scales from the animal’s flank. The sample goes into a tube, labelled and stored. Within moments, the snake is released back into the water, vanishing with a powerful sweep of its tail.
The DNA shock: one famous snake, two species
Back in the lab, that scale, along with others collected across the Amazon basin, rewrote a long-standing assumption about one of the world’s most recognisable reptiles.
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Genetic tests showed that “green anacondas” are not a single species, but at least two: a northern and a southern giant.
Scientists confirmed that:
- Eunectes murinus – the known southern green anaconda – lives in the southern Amazon basin.
- Eunectes akayima – the newly described northern green anaconda – occupies the northern basin and nearby regions.
These two lineages split around 10 million years ago. Since then, they have built up thousands of differences across their genomes, adding up to around 5.5% of their DNA. For comparison, the genetic gap between humans and chimpanzees sits at roughly 2%.
Where the new northern giant lives
The northern green anaconda ranges across a huge swath of wetlands and slow-moving rivers in northern South America. Its stronghold includes parts of:
| Country / region | Presence of northern green anaconda |
|---|---|
| Ecuador | Amazonian lowlands, including Waorani territory |
| Colombia | Orinoco and Amazon drainages |
| Venezuela | Llanos wetlands and forested rivers |
| Trinidad | Wetlands and river systems |
| Guyana, Suriname, French Guiana | Lowland jungle swamps and floodplains |
These snakes favour stagnant or slow-flowing water: oxbow lakes, flooded forests, and reed-filled marshes. Their olive-green skin, flecked with darker blotches, blends almost perfectly with rotting plant matter and shadowed pools.
This camouflage lets them ambush large animals, including capybaras, deer and caimans, as they swim or drink at the water’s edge.
Heaviest snakes on Earth, and still poorly understood
Both northern and southern green anacondas rank among the heaviest snakes on the planet, with some individuals weighing more than 250 kilograms (over 550 pounds). Their bodies can exceed 30 centimetres in girth, thicker than a human thigh.
Despite their fame, scientists still know surprisingly little about how these giants live, breed and move across flooded landscapes.
One clear pattern is size difference between the sexes. Female northern green anacondas grow much larger and bulkier than males. The males stay slimmer and shorter, which shapes what they eat and where they sit in the food web.
Different diets, different dangers
Fry’s team found that female and male northern green anacondas share habitat but not exactly the same menu:
- Females tend to feed lower in the food chain, often targeting herbivores such as deer and capybaras.
- Males more often consume predatory fish and caimans, which already carry contaminants from smaller prey.
This means toxins build up differently in their bodies. The team measured heavy metals in tissue samples and found male snakes carried far higher levels of cadmium and lead than females.
Toxin levels in males were reported as more than ten times higher than in females — a stark signal of pollution.
These metals are linked to oil spills and industrial activity. They can disrupt hormones, damage organs and affect reproduction in both wildlife and people.
What anacondas reveal about human health in the Amazon
The diets of male northern green anacondas overlap with what many riverine communities eat: large fish and, in some areas, caimans or other predatory species. That parallel turns the snakes into living monitors of pollution.
If male anacondas show heavy contamination, there is a strong chance local people accumulating similar toxins through food are at risk too. Fry’s team sees the snakes as an early warning system, flashing danger in ecosystems where formal health monitoring is often limited.
One practical outcome of the research is a food guide Fry is preparing for the Waorani. The idea is not to cut off traditional diets, but to shift choices where contamination risk is highest.
Recommendations focus on vulnerable groups, advising pregnant women and young children to avoid top predators such as arapaima and arowana when pollution is suspected.
These fish sit high in the food chain and can concentrate heavy metals in their tissues. Choosing species lower on the chain, or mixing diets with more plant-based foods and smaller fish, could lower exposure over time.
Why a new giant snake species matters for conservation
Formally recognising Eunectes akayima as a distinct species does more than add another Latin name. It affects how conservationists assess threats and set priorities. Two species may respond differently to habitat loss, hunting pressure or climate shifts.
Protected areas and national regulations often hinge on species lists. If northern and southern populations are lumped together, declines in one region can be hidden by stability in another. Splitting them makes it easier to see where numbers are dropping and where urgent protections are needed.
The discovery also shines a light on Indigenous knowledge. Waorani guides have lived alongside these snakes for generations, reading their movements, seasons and moods. Their tracking skills were central to finding the animals in the first place, and their communities will feel the environmental changes the snakes are signalling.
Key terms and concepts behind the headlines
A few scientific ideas sit quietly behind this dramatic footage:
- Constrictor: A snake that kills prey by wrapping around it and squeezing, stopping blood flow rather than injecting venom.
- Genetic divergence: The process by which populations accumulate DNA differences over time, eventually becoming separate species.
- Biomagnification: The build-up of pollutants as you move up the food chain, from small prey to large predators.
- Indicator species: Animals or plants whose health reflects the broader condition of their habitat.
In this case, northern green anacondas act as indicator species for heavy metal pollution, telling a story that stretches from remote oil fields to dinner tables along the river.
Imagining future encounters with Amazon giants
The newly recognised northern species is the fifth described anaconda, and scientists suspect more genetic surprises may be waiting in isolated swamps and flooded forests. As climate patterns shift and human activities push deeper into the basin, interactions between people and large snakes could change too.
One scenario researchers are watching is how flooding patterns might alter hunting grounds. Longer dry seasons could crowd both wildlife and people into shrinking water sources, raising the odds of conflict with large predators. Detailed knowledge of where different anaconda species move and breed will help local communities plan fishing, farming and tourism in safer ways.
For viewers watching the footage at home, the moment a 5-metre anaconda erupts from a tangle of roots is pure adrenaline. For the Waorani and the scientists beside them, that same moment is also fieldwork, data collection and a glimpse of how a single animal can reveal the hidden pressures reshaping the Amazon.
Originally posted 2026-02-12 16:33:57.