Yellow Anaconda

ORDER: Squamata

FAMILY: Boidae

GENUS: Eunectes

SPECIES: notaeus

These snakes have a pattern of dark brown or bluish black blotches, saddles and spots on a ground color of yellow or tan. Not as large as the Common Anaconda, they can reach an average adult length of ten to twelve feet.

Swamps, brush-covered banks of slow-moving streams and rivers in northern Argentina, Paraguay, southeastern Bolivia and Brazil.

Paca, agouti and other small mammals as well as birds and reptiles. Juveniles apparently feed on fish. Yellow anacondas are constrictors that often wait at water's edge for prey to come to drink. The prey is constricted and suffocated, or pulled under water to drown. They will also actively hunt on land.

Nocturnal and solitary except during courtship. Although anacondas are also known as "water boas" since they spend a large part of their time in water, the Yellow Anaconda is reportedly more arboreal. They are viviparous and produce litters of up to several dozen young, eighteen inches in length. Courtship, mating and birth often take place in water. Lifespan is 15 to 20 years.

Although no true placental connection between female and young exists as it does in mammals, there is undoubtedly a mechanism present that allows for the exchange of oxygen and other elements. Eyes and nostrils are positioned on the top of the head, enabling the anaconda to breathe and see prey while its stocky body is submerged in water.

Boa constrictors and anacondas are considered primitive snakes and have vestigial pelvic girdles and hind limbs. The latter terminate externally as a pair of spurs on either side of the vent. These spurs are larger in males and are used in courtship and mating. The larger relative, the Common Anaconda, is the longest reptile in the world at an average adult length of 27-29 feet. They can weigh several hundred pounds and measure more than 12 inches in diameter.

1 Female. Came here in 2005 from the Sunnyvale SPCA.

Habitat destruction and hunting for skins have contributed to the decline of the Yellow Anaconda. It is listed on CITES II.


  1. Grzimek, h.c. Bernard. Grzimek's Animal Life Encyclopedia Volume 6: Reptiles. 1984. Van Nostrand Reinhold Company, Inc. NYC.
  2. Mehrtens, John. Living Snakes of the World. 1987. Sterling Publishing Co., NYC.

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