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Yellow Anaconda

Eunectes notaeus


Much smaller than its cousin the green anaconda, the yellow anaconda is 9-15 feet long and weighs 66-88 pounds, with females being larger than males. It has yellowish-green scales with brown or blackish bands and overlapping spots that wrap around the entire body. The pattern of yellow and black scales on the underside of the lower tail is unique to each snake.

Yellow Anaconda

Distribution and Habitat

The yellow anaconda is found in southern South America (Paraguay, southern Brazil, northeastern Argentina, and Bolivia). It lives primarily in swamps and marshlands with slow-moving rivers or streams, but can also be observed in forests searching for large game. It tends to float atop the water with its snout barely above the surface.


Yellow anacondas breed between April and May every year. Males follow the scent trails left by females. Yellow anacondas have been known to form breeding balls, consisting of one female and multiple males. These breeding balls have been known to stay together for up to a month. In the breeding ball, males compete for mating access to the female, with the largest male typically winning out over all other males. While a female will typically only breed with one male per year, a large male may successfully outcompete enough males to mate with several females in the same year.

After a 6-month gestation period, the mother gives birth to up to 82 fully-developed live young. These young are able to live on their own from birth and are left by the mother as soon as finishes delivery.

Sexual maturity is reached at 3-4 years. While young anacondas are vulnerable to predation, adults have few enemies, allowing for a lifespan of 15-20 years in the wild.


Yellow anacondas are strictly solitary except for mating. They are generally timid compared to other anacondas, preferring escape to confrontation when threatened, but they will aggressively defend themselves if given no other choice.


An ambush predator, the yellow anaconda will take virtually any animal that comes its way, including birds, turtles, lizards, small mammals, and fish, and are quite capable of taking down large prey such as small deer, peccaries, capybaras, and even caimans. Like other members of its family, the yellow anaconda relies on constriction to kill prey, but it will also drag prey under water and drown it. Although it prefers live prey, the yellow anaconda will take fish carrion. Like most other snakes, the yellow anaconda can go for months without eating if its last prey item was large enough.

Scientific Classification

Phylum Chordata
Subphylum Vertebrata
Class Reptilia
Order Squamata
Suborder Serpentes
family Boidae
genus & species Eunectes notraeus

Animal Diversity Web
World Land Trust

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The Robinson Library >> Science >> Zoology >> Reptiles and Amphibians >> Suborder Serpentes

This page was last updated on March 15, 2018.