Anacondas are related to boa constrictors and pythons. None is venomous. They are constrictors: they suffocate their prey by coiling around it and squeezing. Anacondas will eat almost anything they can find: fish, birds, mammals and other reptiles.
Weights of about 200 kg (441 lb.) to 500 kg (1,100 lb.) and a length of up to 11 m (36 ft.) are sometimes given for this species. Such measurements make it the most massive of the giant snakes, but these extremes are field reports that lack verification. Adults of 5.5 to 6 m (18 to 20 feet) are average, but they are always heavier than a python of the same length. The body is dark green (hence the name green anaconda) with large black dorsal spots and small lateral spots with lighter yellow centres.
Adults can grow to more than 9 m (29.5 ft.) in length. The reticulated python is, on average, usually longer than the average anaconda, but because the green anaconda is much heavier than the other large constrictors, if you consider both length and weight, it is the largest snake in the world.
The green anaconda occurs in South America, in the Amazon and Orinoco rivers system, and as far south as Bolivia. It is also found in Trinidad. Anacondas are tied very closely to water, and they are excellent swimmers and divers.