Size: An average adult weighs 150kg but can weigh up to 250 kg. They are the heaviest snakes in the world. Length; up to 9 metres in length (females are usually 6 to 8m in length whilst males are 3 to 4m).

Habitat and Distribution: Green anacondas are found throughout tropical South America, east of the Andes, mainly in the Amazon and Orinoco basins and in the Guianas. These snakes are mainly aquatic but will also hunt on land. They prefer sluggish or still waters rather than clear, fast moving streams.

Age: Approximately 25 to 30 years.

Groups and Breeding: Anacondas are usually solitary animals, only coming together during breeding season.

During this period, the female will emit a pheromone trail which attracts males to her. She will form a ‘breeding ball’ with between 2 to 12 males coiled around her for up to 4 weeks. During this time the males wrestle until the strongest wins and successfully mates with the female.

A typical female will give birth to between 20 to 40 live young but sometimes up to 100 young (this snake does not lay eggs) after a gestation of 6 months, usually in April and May. Typically a baby measures around 70 to 80 cm in length but will grow quickly and reach sexual maturity within a few years.

Diet: Anacondas are not venomous and kill their prey by constricting them. They typically feed on large rodents, tapirs, capybaras, deer, peccaries, fish, turtles, birds, sheep, dogs, and aquatic reptiles like caiman. Younger anacondas feed on mice, rats, chicks, frogs and fish.

• The only area on the anaconda without scales is the cloaca (where poo and babies emerge!). This area contains glands which secrete a foul-smelling liquid (musk) which is poisonous to small organisms. It is thought that this is a type of natural pesticide.
• The patterns along the lower side of the tail are yellow and black and are unique to each individual (like a fingerprint).
• They have been known occasionally to prey on jaguars and attacks on humans can be confirmed, although this is rare.
• Anacondas can unhinge their jaws to swallow whole prey much larger than they are. Because of this it can take a long time for them to digest their last meal. There is a record of one snake in captivity fasting for 2 years
• New born anacondas can swim, hunt and care for themselves within hours of being born.
• The name "anaconda" is thought to originate from a Sri Lankan word meaning either "elephant killer" or whip snake. This may seem strange as anacondas do not come from Sri Lanka but was thought to be based on the description by the British naturalist John Ray who in 1693 described one of the snakes from India as: "anacandaia of the Ceylonese, i.e. he that crushes the limbs of the buffaloes and yoke beasts."