Green anaconda

Eunectes murinus

The green anaconda is a constricting serpent in the boa family that may be the heaviest snake in the world, rivalling the reticulated python from Southeast Asia.


It can be found in the basins of large tropical South American rivers, in jungle regions and floodable savannahs, using the somewhat temporary pools of water that form there.


With aquatic habits, it is a very good swimmer and a powerful predator that can capture mammals, birds, fish and caimans.

Natural habit

South America, the river basins of the Amazon and Orinoco and other sites in Brazil, Bolivia, Colombia, Ecuador, Guiana, French Guiana, Surinam, Peru, Paraguay, Venezuela and the island of Trinidad. There are small populations that were introduced to the state of Florida, in the United States. 

South America
  • Distribution / Resident
  • Breeding
  • Wintering
  • Subspecies

Risk level

  • Extint
  • Extint in the wild
  • Critically endangered
  • In Danger
  • Vulnerable
  • Near threatened
  • Minor concern
  • Insufficient data
  • Not evaluated
Not evaluated



Physical characteristics

More than 100 kg
Birth Weight:
More than 8 m
More than 30 years in captivity


Social life


120 - 210
20 - 40 eggs

Discover how they are



This is a large snake with a heavy body and a broad head. The body colour is olive green or greenish grey, with large black spots distributed irregularly over the body. The bottom of the flank has a series of a dark rings with orange eyespots.


Females, much larger than males, grow to an average of five to seven metres long and weigh from 45 to 180 kg, while males' maximum length is some two and a half metres.


This large semi-aquatic snakes inhabit slow and shallow freshwater watercourses, as well as floodable areas of wetland wooded savannahs and open grassy stretches of swamps.


It feeds on a large variety of mammals, such as capybaras, peccaries and rodents, but can also eat aquatic birds, fish and caimans. The largest specimens can even swallow animals as large as tapirs and jaguars.


Green anaconda mating takes place between April and May. Females attract males with olfactory signals, and it is normal for up to a dozen males to slither around the female, trying to copulate with her. This ovoviviparous species gives birth to living babies after five to seven months incubation inside the mother. They give birth in shallow waters in the afternoon or at night, at the end of the wet season, and they have from 20 to 40 babies per pregnancy. Females normally breed only once every two or three years. 


Green anacondas are excellent swimmers and spend most of their time in the water, although they can also take to the land, heading to the highest branches of trees that are close to or overhang the waterways.  They primarily hunt animals that come to the water to drink, which they ambush, clamping on to the prey with their jaws and asphyxiating them by wrapping around them and squeezing.  They eat their prey whole, and digesting larger animals can take several weeks.


Besides human beings, the only natural enemy of adult anacondas is the jaguar.

Status and conservation programs

The main danger to the green anaconda is the destruction and degradation of its habitat. In some regions of its extensive area of distribution, the populations are becoming scarcer, and it is even considered extinct in Argentina.