Three to five extant and one extinct species are currently recognized, including one of the largest snakes in the world, E. murinus, the green anaconda.

[citation needed] The recent fossil record of Eunectes is relatively sparse compared to other vertebrates and other genera of snakes.

The word anaconda is derived from the name of a snake from Ceylon (Sri Lanka) that John Ray described in Latin in his Synopsis Methodica Animalium (1693) as serpens indicus bubalinus anacandaia zeylonibus, ides bubalorum aliorumque jumentorum membra conterens.

[8] Henry Yule in his 1886 work Hobson-Jobson, notes that the word became more popular due to a piece of fiction published in 1768 in the Scots Magazine by a certain R. Edwin.

[a] Yule and Frank Wall noted that the snake was a python and suggested a Tamil origin anai-kondra meaning elephant killer.

[10] A Sinhalese origin was also suggested by Donald Ferguson who pointed out that the word Henakandaya (hena lightning/large and kanda stem/trunk) was used in Sri Lanka for the small whip snake (Ahaetulla pulverulenta)[11] and somehow got misapplied to the python before myths were created.

Videos exist of anacondas preying on domestic animals such as goats and sometimes even jaguars[16] that venture too close to the water.

Local communities and some European explorers have given accounts of giant anacondas, legendary snakes of much greater proportion than any confirmed specimen.

[24] In anaconda breeding balls, several males coil around one female and attempt to position themselves as close to her cloaca as possible where they use their pelvic spurs to "tickle" and encourage her to allow penetration.

One day, without telling his anaconda wife, Yube decided to return to the land of men and resume his old human form.