Scientists Discover The World’s Largest Snake Species

The reticulated python (Malayopython reticulatus) may be the longest snake on Earth, but pound for pound the anaconda buries it. That heft is why the green anaconda wears the crown as the world's largest snake species, and in 2024 that crown got a new claimant. Long treated as a single species, Eunectes murinus (now the "southern green anaconda") was split in two when a team of researchers, trailed by a National Geographic film crew, confirmed a genetically distinct northern population: Eunectes akayima, the "northern green anaconda." It arrived making an entrance, too. One female measured at least 21 feet (6.3 meters) and tipped the scales past 200 kilograms (441 pounds). So come along for a vicarious trip down to Ecuador's Amazon jungle to meet the planet's heftiest serpent.

The Paradigm-Shifting Expedition

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 "Pole to Pole with Will Smith" docuseries. 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, 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 And Southern Green Anacondas

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 (olive-colored with large black spots), 10 million years of divergent evolution and a whopping 5.5% difference in genetic makeup separate the two anaconda species. For a pertinent point of reference, we are approximately 98.8% similar to chimpanzees, 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 constrictors 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, 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, where the added buoyancy offers support and maneuverability. They are specially adapted for it: the position of their eyes and nostrils lets them stay almost entirely submerged for long stretches. That skill is what makes them such lethal ambush predators. 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 whole.

The Largest Snakes Ever Recorded, And Tantalizing Rumors

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). Professor Fry's recent findings did not quite surpass that, but considering the small sample size and the legendary local stories, it is reasonable to expect a new record-holder to emerge from this Ecuadorian ecosystem. To date, only a few scientific teams have been granted access to the Baihuaeri Waorani Territory, so who knows what other enormous constrictors might be lurking beneath the intricate waterways and dense canopy? If the rumors are true, anacondas measuring 25 feet (7.6 meters) and weighing over 1,100 pounds (500 kilograms) have been spotted in this part of the Amazon.

Escalating Environmental Pressures

Given its crucial role as an apex predator, its dependence on fragile habitats, and the ongoing destruction of large areas of the Amazon rainforest, researchers consider anacondas to be indicator or keystone species, meaning their population status reflects the overall health of the entire ecosystem. With the exciting addition of the northern green anaconda to the catalog of known Amazonian animals, perhaps increased awareness and funding can be raised to help preserve this vital river basin.

As expected, 20-foot snakes need a large territory with a balanced food chain. Sadly, experts estimate that the northern green anaconda has already lost 20 to 31% of its habitat due to agriculture-driven deforestation. But habitat loss is only part of the issue; habitat degradation is also widespread. Heavy metal pollution from mining, petrochemicals that disrupt fertility after oil spills, and regular threats like forest fires and droughts all threaten this 10-million-year-old species.

Final Thoughts

It is hard to imagine megafauna remaining undiscovered today, which only emphasizes how expansive and enigmatic the Amazon still is. The Waorani have always known these giants shared their land; Western science is only now catching up. Through a collaborative, cross-cultural effort, we finally have a name for the largest snake in the world's "new" relative, and a fresh reason to fight for the rainforest it calls home.