Green Anaconda: Meet the Heaviest Snake in the World

By: Desiree Bowie  | 
A spotted snake coils around a sunken tree branch in murky water
A green anaconda supports itself on a sunken tree branch in the Rio Formoso, in Mato Grosso do Sul, Brazil. Julian Gunther / Getty Images

With its immense size, aquatic lifestyle and ability to evoke both awe and fear, South America's green anaconda has captivated the imaginations of naturalists and adventurers alike.

But did you know that these colossal snakes, known for their presence in the remote waters of the Amazon rainforest, have found an unexpected home in the heart of the United States? Nestled within the lush and iconic expanse of the Florida Everglades, a landscape famous for its alligators and diverse wildlife, the snake has quickly established itself.


In this article, we'll explore the green anaconda's habitat, mating and hunting behavior and amphibious lifestyle.

The Green Anaconda's Name Translates to 'Good Swimmer'

The green anaconda is the largest and most well-known species within the genus Eunectes, a group of large, nonvenomous, boa-like snakes found in South America.

Also known as a common anaconda, this species from the boa family is known for being one of the heaviest and longest snakes in the world, often overshadowing its relatives, such as the yellow anaconda (Eunectes notaeus).


The snake's scientific name, Eunectes murinus, offers insights into its origins and characteristics. The genus name "Eunectes" is derived from the Greek words "eu," meaning "good," and "nectes," meaning "swimmer." This nomenclature aptly describes the snake's exceptional aquatic capabilities, emphasizing its proficiency in water.

The species name "murinus" is derived from the Latin word "murena," which refers to the moray eel, a serpentine aquatic creature. The green anaconda is not closely related to eels, but the name is meant to underscore the snake's aquatic lifestyle and serpentlike appearance.


Physical Features of Green Anacondas

The green anaconda is known for its massive size and distinctive physical features. It has a thick, muscular body built for constricting and subduing prey.

Its skin is a dark green color, providing excellent camouflage in the murky waters of the anaconda's rainforest habitat. This green coloration is patterned with black spots and stripes, which further aid in blending into the dense vegetation and shadowy waters.


The snake's head is small compared to its body, with eyes and nostrils positioned on top, allowing it to see and breathe while most of its body is submerged. To facilitate its aquatic hunt, the snake's scales are smooth, which assists in minimizing resistance while swimming.

Stretchy Adaptation

The green anaconda, like other large snakes, has a remarkable jaw structure facilitated by specialized ligaments that allow for significant stretching and flexibility. These ligaments, known as the mandibular symphysis, connect the two halves of the lower jaw.

Unlike in humans, where the jaw is rigidly fused, these ligaments in snakes are extremely elastic, enabling the jaw halves to move independently and spread apart.

Similar stretchable ligaments are present at the snake's quadrate bones, located at the back of the skull, further aiding in widening the gape. These stretchy ligaments are crucial for the feeding habits of the anaconda, as they primarily prey on sizable animals, like wild pigs, jaguars and deer.

The anaconda's heft and adaptability have contributed to the creature's terrifying reputation. But how could one not be frightened when encountering the largest snake in the world?


These remarkable creatures can exceed 20 feet (6 meters) and have even been documented at lengths over 30 feet (9 meters). However, their size is not just about length; it's also about sheer mass. Green anacondas can weigh over 500 pounds (227 kilograms), making them significantly heavier than many other snake species in the world.

While other massive snakes — like the reticulated python, the Burmese python and the African rock python — are known for their length, green anacondas surpass them all in terms of bulk. Aside from earning the title of world's largest snake, their impressive size is advantageous in their aquatic habitat, where they often overpower large prey.

But they don't just dwell in the water.


On Land and in Water

The green anaconda is native to the tropical rainforests, swamps, marshes, slow-moving rivers and wetlands of South America. Specifically, its range includes countries such as Brazil, Venezuela, Colombia, Ecuador, Peru and parts of Bolivia.

These snakes are well-adapted to the lush and aquatic environments of the Amazon basin and the surrounding regions.


While the giant anaconda prefers the water, it also ventures onto land for basking or seeking refuge in burrows or vegetation cover from extreme weather. While not quite as agile outside of the water, you still would want to avoid facing this snake on land.

This amphibious lifestyle allows green anacondas to thrive in both aquatic and terrestrial habitats, making them apex predators in their ecosystems. They prey on a variety of animals from the water and, on occasion, land.



Green anacondas are opportunistic hunters. Unlike vipers or cobras, this snake species does not possess venom-producing glands or specialized fangs for injecting venom into their prey. Because of this, they have to rely on their physical strength and stealth for hunting.

This adaptability is how they've become one of the top predators in their aquatic ecosystems.


When it's time for the hunt, these snakes employ a combination of strategies to capture and kill prey, with their primary method being constriction. The skilled ambush predators often wait patiently — completely submerged in water or concealed in vegetation — for suitable prey to approach.

When prey comes within striking distance, anacondas launch a rapid strike, using their powerful jaws and sharp teeth to grasp the victim. Once they have a firm grip, green anacondas use their muscular bodies to coil around they prey.

Constriction serves several purposes, including preventing the prey from breathing, disrupting blood flow, and potentially causing bone fractures.

After successful constriction and immobilization, anacondas begin swallowing the prey whole. Their highly flexible jaws allow them to stretch around large prey.



The large snake is an apex predator with a diverse diet that reflects their status as one of the top predators in their ecosystem. It primarily preys on a variety of animals, including capybaras (which are the largest rodents globally), caimans, deer, peccaries and even other snakes.

The anaconda is also known to capture birds, particularly those approaching the water's edge to drink or nest. Its stealthy underwater approach makes it an effective avian hunter. Fish and aquatic birds also contribute to its diet.


Thanks to their highly elastic skin and muscles, these nonvenomous constrictors can swallow prey larger than their own body.

After ingesting large prey, green anacondas undergo a period of slow digestion. During this time, their metabolic rate increases, facilitating the efficient breakdown and absorption of nutrients from the substantial meal.



Green anacondas have distinctive mating habits that align with the onset of the rainy season, typically occurring in the South American wetlands and rainforests from November to April. During this period, the increased water levels create a conducive environment for reproduction.

Adult males, upon reaching sexual maturity, engage in intense physical combat for the opportunity to mate with a receptive female. This combat, involving intertwining and overpowering each other, determines which male earns the right to approach the female.


In the breeding season, adult females may attract several males, often forming a "breeding ball." This happens when multiple males simultaneously coil around one female, all competing to mate. This process can extend over several hours to days.

Post-mating, the female enters a gestation period lasting around six to seven months. Green anacondas are ovoviviparous, giving birth to live young. The number of offspring varies significantly. Following birth, the female displays maternal care, protecting her young for a brief period before moving on.


Average Lifespan

The green anaconda typically lives around 10 to 15 years in the wild, although some individuals may live longer under optimal conditions.

In captivity, where threats are minimized, and nutrition and health are regularly monitored, the snakes can live longer, often exceeding 20 years. The longest recorded lifespan for a green anaconda in captivity is over 30 years.


In the wild, their life expectancy is often shorter due to challenges like habitat loss, hunting and competition for food. The anaconda’s large size can help deter most predators, but young snakes are more vulnerable to threats from other wildlife and environmental pressures.

This article was created in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.