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Anaconda snake (Eunectes murinus) in the Llanos grasslands of Venezuela. © Mark Godfrey

The anaconda hunts its prey primarily by lurking in murky water.

The Giant Snake of the Amazon

Stretching as long as 29 feet and weighing as much as 550 pounds, the green anaconda is one of the world’s largest snakes. Only the reticulated python grows longer, and it weighs less than the green anaconda. The snake inhabits swampy river valleys and stream banks in much of South America, east of the Andes and south to Argentina. Though it spends much of its life in sluggish freshwater, it also occasionally climbs trees and bushes with the help of its prehensile tail.

The green anaconda hunts its prey primarily by lurking in murky water, waiting for animals to come drink, then seizing the prey with its teeth and killing it by constricting its body around the animal. Usually dinner is not completely crushed, just squeezed tight enough to prevent it from breathing. Typical prey includes large rodents, birds, dogs, sheep, aquatic reptiles and any other vertebrate it can catch and swallow.  After unhinging its jaws, it usually swallows prey head first so that the legs fold neatly along the body, facilitating the process. It then contracts its powerful muscles in waves to compress the prey animal’s body. 

Mating in April and May, green anacondas often form “breeding balls” of 2-12 male snakes coiled around a single female. The breeding ball is essentially a glacially slow wresting match between the males for the right to mate with the female and can last as long as 2-4 weeks. Gestation lasts about 6 months, after which a litter of 20-40 live young, each about 26 inches long, are born. Young green anacondas grow quickly until sexual maturity and then slow, living an average of 10 years in the wild.