Scientists shocked to discover new species of green anaconda, world’s largest snake

The green anaconda has long been considered one of the most fearsome and mysterious animals in the Amazon. Our new research, published in Diversity, shakes up the scientific understanding of this magnificent creature, revealing that they are actually two genetically different species. This surprising discovery opens a new chapter in the conservation of this main predator of the jungle.

Green anacondas are the heaviest snakes in the world and among the longest. Found primarily in the rivers and wetlands of South America, they are renowned for their lightning speed and ability to asphyxiate enormous prey and then swallow it whole.

My colleagues and I were shocked to discover significant genetic differences between the two anaconda species. Given that the reptile is such a large vertebrate, it is remarkable that this difference has gone unnoticed until now.

Conservation strategies for green anacondas now need to be reassessed, to help each unique species cope with threats such as climate change, habitat degradation and pollution. The results also show the urgent need to better understand the diversity of Earth’s animal and plant species before it is too late.

An impressive predator

Historically, four species of anacondas have been recognized, including green anacondas (also known as giant anacondas).

Green anacondas are true monsters of the reptile world. The largest females can measure more than seven meters in length and weigh more than 250 kilograms.

Snakes are well adapted to a life lived primarily in water. Their nostrils and eyes are above their head, allowing them to see and breathe while the rest of their body is submerged. Anacondas are olive colored with large black spots, which allows them to blend in with their surroundings.

Snakes inhabit the lush and complex waterways of the Amazon and Orinoco basins of South America. They are known for their stealth, patience, and surprising agility. The buoyancy of the water supports the animal’s substantial mass and allows it to move easily and jump to ambush prey as large as capybaras (giant rodents), caimans (reptiles of the alligator family ) and deer.

Green anacondas are not venomous. Instead, they bring down their prey using their large, flexible jaws, then crush them with their powerful bodies before swallowing them.

As apex predators, green anacondas are essential to maintaining the balance of their ecosystems. This role extends beyond their hunting. Their very presence alters the behavior of a wide range of other species, influencing where and how they feed, reproduce and migrate.

Anacondas are very sensitive to environmental changes. Healthy anaconda populations indicate healthy, vibrant ecosystems with abundant food resources and clean water. Declining anaconda numbers may be a warning sign of environmental distress. It is therefore crucial to know which anaconda species exist and monitor their numbers.

To date, little research has been conducted on the genetic differences between anaconda species. Our research aimed to fill this knowledge gap.

Unraveling anaconda genes

We surveyed representative samples of all anaconda species across their entire distribution, in nine countries.

Our project lasted almost 20 years. Crucial pieces of the puzzle come from samples we collected during a 2022 expedition to the Bameno region, Baihuaeri Waorani territory, Ecuadorian Amazon. We made this trip at the invitation and in collaboration with Waorani leader Penti Baihua. Actor Will Smith also joined the expedition, as part of a series he is filming for National Geographic.

We studied anacondas in various locations across their range in South America. The conditions were difficult. We went up muddy rivers and crossed swamps. The heat was relentless and swarms of insects were everywhere.

We collected data such as habitat type and location, as well as precipitation patterns. We also collected tissue and/or blood from each sample and analyzed them in the laboratory. This revealed that the green anaconda, once thought to be a single species, is actually two genetically distinct species.

The first is the known species, Eunectes murinus, which lives in Peru, Bolivia, French Guiana and Brazil. We gave it the common name “southern green anaconda.” The second newly identified species is Eunectes akayima or “northern green anaconda”, found in Ecuador, Colombia, Venezuela, Trinidad, Guyana, Suriname and French Guiana.

We also identified the period during which the green anaconda diverged into two species: almost 10 million years ago.

The two species of green anaconda appear almost identical and no obvious geographic barriers exist to separate them. But their level of genetic divergence – 5.5% – is staggering. For comparison, the genetic difference between humans and apes is about 2%.

Preserving the web of life

Our research has helped to resolve part of the mystery surrounding green anacondas. This discovery has important implications for the conservation of these species, particularly for the newly identified northern green anaconda.

Until now, the two species were managed as a single entity. But each may have different niches and ecological ranges and face different threats.

Tailored conservation strategies must be designed to safeguard the future of both species. This may include new legal protections and initiatives to protect habitat. It may also involve measures to mitigate the damage caused by climate change, deforestation and pollution, such as the devastating effects of oil spills on aquatic habitats.

Our research also highlights the complexities linked to the conservation of biodiversity. When species go unrecognized, they can slip through the cracks of conservation programs. By integrating genetic taxonomy into conservation planning, we can better preserve the complex web of life on Earth, both the species we know today and those yet to be discovered.

This article is republished from The Conversation under a Creative Commons license. Read the original article.