By Fernando Flores - Own work, CC BY-SA 3.0,

Scientists Discover The World’s Largest Snake Species

The reticulated python (Malayopython reticulatus) may be the longest (on average) extant snake species, but the infamous anaconda is much heavier. The latter, specifically the green anaconda, therefore, consistently earns the crown of the world's largest snake species. Up until 2022, it was thought that this enormous member of the boa family was a single species, i.e., Eunectes murinus (now known as the "southern green anaconda"), but a team of researchers, accompanied by a National Geographic film crew, recently documented a new species, i.e. Eunectes akayima (aka the "northern green anaconda"), and it's already tipping the scales. A female specimen was confirmed to be at least 21 feet (6.3 meters) long and weigh in excess of 200 kilograms (441 pounds). So come along for a vicarious trip down to Ecuador's Amazon jungle to learn more about the planet's heftiest serpents.

The Paradigm-Shifting Expedition

Boating through the Amazon Jungles in Equador.
Boating through the Amazon Jungles in Equador.

Thanks to an invitation by Waorani Chief Penti Baihua and the accompaniment of Indigenous hunters, Professor Bryan Fry of the University of Queensland was able to lead a team of researchers deep into the Ecuadorian Amazon. The impetus for the expedition that lasted ten days (but was almost 20 years in the making) was two-fold: investigate rumors that the largest living anacondas lurk in the Bameno region of the Baihuaeri Waorani Territory and obtain footage for National Geographic's upcoming "Pole to Pole with Will Smith'' docu-series. Because of the latter motivation, a film crew and even the actors were on hand for the groundbreaking discoveries.

One of the viral videos to come out of this South American snake-seeking mission was of Dutch biologist Freek Vonk swimming alongside a submerged anaconda of incredible proportions. Armed with nothing but a basic breathing apparatus, Vonk shows no hesitation in getting right up close to the behemoth reptile, thereby acting as a helpful size reference in the process. Authorities initially deemed the female northern green anaconda to be 26 feet in length, though many sources have since revised that figure to 20.8 feet (a remarkable find, all the same).

Differentiating Northern/Southern Green Anacondas

The Southern Green anaconda (Eunectes murinus)
The Southern Green anaconda (Eunectes murinus)

Getting visual confirmation of a new species of green anaconda gave immediate validation for the intensive expedition. But the genetic analysis that followed triggered even more scientific excitement. While the newly-discovered northern green anaconda resembles its cousin to the south in both size and appearance (i.e., olive-colored with large black spots), 10 million years of divergent evolution and a whopping 5.5% difference in genetic makeup separates the two anaconda species. For a pertinent point of reference, we are approximately 98.8% similar to chimpanzees (i.e., our closest living relatives from whom we diverged between 6.5 and 9.3 million years ago).

Outside the lab, one helpful way to distinguish the two gargantuan constrictor snakes is by geographical domain. The southern green anaconda can be found in parts of Peru, Bolivia, French Guiana, and Brazil. In contrast, the northern green anaconda is now thought to lurk in Colombia, Venezuela, Trinidad, Guyana, Suriname, French Guiana (the two species overlap here), and, of course, Ecuador. The green anaconda's large South American distribution covers the Amazon Basin and the Orinoco Basin (i.e., the continent's third-largest watershed).

Like all anacondas (now five recognized species), green anacondas prefer to spend most of their time in the water, as the added buoyancy offers support and maneuverability. Anacondas are specially adapted for life in the water, as the position of their eyes and nostrils allows them to remain almost entirely submerged for long periods. This skill is particularly helpful when it comes time to hunt, as these apex predators use ambush tactics. Green anacondas are exceptionally patient - lying in wait until deer, capybaras, and even caimans come within striking distance, whereupon the unsuspecting prey is constricted, asphyxiated, crushed, and swallowed hole.

The Largest Snakes Ever Recorded…And Tantalizing Rumors

Green Anaconda
A Green anaconda slithering through sand in Brazil.

According to the Natural History Museum, the largest green anaconda ever recorded was 27.7 feet long (8.43 meters), 3.6 feet wide (1.11 meters), and weighed over 500 pounds (227 kilograms). While Professor Fry's recent findings didn't quite top that, given the small sample size combined with the legendary local anecdotes, it is reasonable to expect a new champion snake to emerge from the tantalizing Ecuadorian ecosystem. To date, only a handful of scientific teams have been granted access to the Baihuaeri Waorani Territory, so who knows what other colossal constrictors lie beneath the complex waterways and dense canopy? If rumors are to be believed, anacondas measuring 25 feet (7.5 meters) and weighing more than 1,100 pounds (500 kilograms) have been spotted in this part of the Amazon.

Escalating Environmental Pressures

View of the Amazon Jungle Yasuni, Ecuador
Thick foliage along a river in the Amazon Jungle Yasuni, Equador.

Given its vital role as an apex predator, its reliance on fragile habitats, and the ongoing destruction of large swaths of the Amazon rainforest, researchers consider anacondas to be an indicator/keystone species - meaning their population status informs the general health of the entire ecosystem. With the exciting addition of the northern green anaconda to the catalog of known Amazonian animals, perhaps more awareness and funds can be raised to preserve this vital river basin.

As one might imagine, 20-foot snakes require a large territory stocked with a well-balanced food chain. Unfortunately, experts estimate that the northern green anaconda has already lost 20-31 percent of its habitat due to agriculture-driven deforestation. However, habitat loss is only part of the picture; habitat degradation is rampant. Heavy metal pollution caused by mining activity and fertility-disrupting petrochemicals that leak into the waterways following oil spills, along with the usual culprits of forest fires and droughts, all put pressure on the 10-million-year-old species.

Final Thoughts

It is difficult to imagine how megafauna can remain undiscovered in this day and age. But this goes to show just how vast, mysterious, and valuable the Amazon truly is. Yes, the Waorani people have known of the titans slithering through their territory for some time. Still, the northern green anaconda has only just been added to the annals of Western science. Thanks to a collaborative effort that spanned cultures and disciplines, the world now knows about the world's largest snake's "new" cousin.


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