This is believed to be the largest species of snake in the world, although it is difficult to gauge the length of gigantic snakes.
The scientific name of these snakes, Eunectes, means "good swimmer" and reflects their aquatic lifestyle. Besides capturing prey in the water, they will also grab animals that come to drink in the forest water holes, which they will kill by constriction. Anacondas can hunt in total darkness, thanks to heat-seeking pits along their lips, allowing them to detect the presence of warm-blooded prey. They can also pick up the sound of movement, even in water.
Compared to their huge bodies, green anacondas have small heads. Their bodies are covered in smooth olive scales, and they have black ovals on their backs. The males are smaller than the females. The young, born live from the mother, measure about 66 cm (26 in) at birth.
Distribution: South America, east of the Andes, occurring throughout the Amazon and Orinoco river basins, extending into the Guianas, usually encountered close to areas of water.
Habitat: Wetlands and flooded forests.
Weight: 107 - 250 kg (235 - 550 lb); females are much larger.
Length: Average 6 m (20 ft), but much bigger individuals have been recorded.
Maturity: Females 3 years; males 18 months.
Gestation Period: 6 - 7 months.
Breeding: 20 - 100.
Food: Large fish, crocodilians, deer, monkeys, occasionally humans.
Lifespan: 10 - 30 years.
The green anaconda's appearance helps conceal its presence. The underparts are yellowish.
The bones in the skull are relatively flexible. This helps the snake to swallow large prey.
The black blotches on these snakes are variable, enabling individuals to be distinguished.
Present near the tail, these aid mating. They are actually the vestigial remains of the hind limbs.
Female green anacondas will not feed while carrying their eggs, although they may have killed and eaten the male after mating.
These snakes have 100 backward-pointing teeth in their jaws, with more running across the roof of the mouth.