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The Anaconda belongs to the boa constrictor family of snakes. It is the heaviest snake in the world, and one of the longest.

Anaconda (<i>Eunectes murinus</i>) swimming through a river in the Llanos (plains), ... rel= © WWF / Bruno PAMBOUR

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Key Facts
Common name
Common Names

Anaconda, common ancaonda, green anaconda, water boa




Latin name

Scientific Name

Eunectes Murinus



Up to 95kg

The 'bull-killer' of the Amazon
Although it lives near water and is an expert swimmer, the anaconda preys on terrestrial mammals and birds that come to the river to drink.

It is very strong and, despite appearing sluggish on land, can easily overcome large prey, including small species of deer or even small crocodiles (caimans). It kills large mammals by coiling its body around them and suffocating them.

Physical Description
The anaconda is dark green in colour with alternating oval black spots. Similar spots with yellow-ochre centres are along the sides of its body. It has a large narrow head. The eyes and nostrils are set on the top of its head, which enables it to see and breathe while mostly submerged.

Ecology and Habitat
Found in South American countries east of the Andes including Colombia, Venezuela, the Guianas, Ecuador, Peru, Bolivia, Brazil and the island of Trinidad. It spends most of its life in or near water, even giving birth in water. They prefer sluggish or still waters rather than clear, swift flowing streams and are therefore found at relatively low altitudes.

Priority region

What is WWF doing?

WWF is working in the Amazon region with government authorities, local and indigenous communities, non-governmental organizations, the private sector and others to protect large parts of the Amazon and its unique biodiversity and ecological functions and services. This is being achieved through:

  • Promoting the responsible use of natural resources and sustainable management
  • Ensuring environmental and social standards for infrastructure development, particularly road and dam projects
  • Developing national programmes for reducing emissions from deforestation
  • Consolidating and expanding protected areas
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Did you know?

  • Spanish explorers called it matatoro (bull killer) because of exaggerated stories about its length and general body size. Some even believe its name is derived from a Tamil word anaikondran meaning elephant killer!