Green Anaconda

Green Anaconda facts at a glance

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The world's heaviest snake

While the reticulated python can grow longer, the green anaconda is the heaviest and bulkiest snake on Earth, with large individuals reaching about 5 m and weighing 70 kg or more. Its body is thick and muscular, olive-green with black oval blotches that provide camouflage in murky water and among vegetation. Females are considerably larger than males, a pattern common among constricting snakes. The eyes and nostrils sit high on the head, letting the snake lie almost fully submerged while watching for prey.

A life in the water

Green anacondas are semi-aquatic and spend most of their lives in and around water, favouring swamps, marshes and slow-moving tropical rivers in the Amazon and Orinoco basins. Their heavy bodies are supported by water, allowing them to move with surprising ease when submerged even though they are slow and cumbersome on land. On the ground they slither at only a few kilometres per hour, but in water they swim smoothly and can stay under for many minutes. This aquatic habit gives them both cover for ambush and relief from their own great weight.

Hunting and diet

The green anaconda is a carnivore and an ambush predator, lying still in shallow water until an animal comes to drink or wade past. It seizes prey with its backward-curving teeth, throws coils around the victim and constricts, tightening with each breath the animal takes until it can no longer breathe. It then swallows the prey whole, head first. Its diet includes capybaras, caimans, deer, fish, turtles and birds, and a large meal can sustain the snake for weeks or months before it needs to feed again.

Reproduction

Green anacondas give birth to live young rather than laying eggs, with the developing embryos nourished inside the mother. During the breeding season several males may gather around a single large female, forming a slow-moving mass sometimes called a breeding ball as they compete to mate. After a gestation of around six to seven months, the female produces a litter that can range from a handful to several dozen young snakes. The newborns are already around 60 cm to a metre long and are independent from birth.

Anacondas and people

Anacondas feature heavily in legend and film, where they are often shown as monsters that hunt humans, but attacks on people are extremely rare. A wild anaconda is far more likely to slip away into the water than to confront a person. They are not venomous and pose little threat away from careless handling. Listed as Least Concern, the green anaconda remains widespread across tropical South America, though habitat loss and hunting for skins are local pressures.

Did you know? Green Anaconda facts

• The green anaconda is the heaviest snake in the world.
• It kills by constriction, squeezing prey until it cannot breathe.
• Anacondas spend much of their life in water, where their bulk is supported.
• Females are far larger than males and may form breeding 'balls' of many snakes.
• Their eyes and nostrils sit on top of the head for breathing while submerged.
• Despite myths, anacondas pose little threat to people.

Diet & feeding

Green anacondas are ambush constrictors eating fish, caiman, capybara, birds, and other mammals, taking large prey that sustains them for long periods.

Adaptations

• A massive, muscular body constricts large prey with overwhelming force.
• Eyes and nostrils on top of the head allow ambush from just below the surface.
• Aquatic habits let water support the snake's enormous weight.
• An expandable jaw and body swallow prey far wider than the head.

Behaviour & ecology

• Green anacondas ambush prey at the water's edge, then constrict and swallow it whole.
• They are largely aquatic, lurking in slow rivers, swamps, and marshes.
• Several males may court a single large female in a mating ball.
• After a large meal they may not eat again for weeks.

Communication

• Anacondas rely on scent (tongue-flicking) to track mates and prey.
• Pheromone trails draw males to receptive females.
• They are largely silent, using posture if threatened.

Habitat & range

Green anacondas live in the slow rivers, swamps, and flooded grasslands of tropical South America, especially the Amazon and Orinoco basins.

Ecological role

As a giant aquatic constrictor, the green anaconda is an apex predator of South American wetlands, regulating populations of fish, reptiles, birds, and mammals.

Conservation status of the Green Anaconda

Sources & references

This guide is compiled and reviewed against established zoological and conservation references. Key sources for the Green Anaconda:

• IUCN Red List of Threatened Species

  Conservation status (Least Concern) reflects the IUCN Red List category for Eunectes murinus.

• Anaconda assessments. IUCN Red List of Threatened Species.

  Status and range (Eunectes murinus).

• The Reptile Database (reptile-database.org).

  Taxonomy and distribution.

• Animal Diversity Web — Eunectes murinus. University of Michigan Museum of Zoology.

  Life history, morphology, and range.

• Global Animal Guide editorial standards

  How we research, source, review, and update every guide for accuracy.