The green anaconda is dark green in color with black oval patches on its back. This pattern blends in with the wet, dense vegetation of its habitat. The sides have similar spots with yellow centers.
The scales on its belly are yellow and black. The scales on the underside of the tail have a particular pattern, which is unique to each snake. It's a form of identification, like a human fingerprint.
The eyes and nostrils are on the top of the head, enabling the anaconda to breathe and to see its prey while its body lays submerged under water. They can stay completely submerged for ten minutes. While they are agile swimmers, they sometimes prefer to let the river's current carry them downstream with only their nostrils above the surface.
Anacondas are a source of many myths that exaggerate their size and attacks on humans. Reports of giant constrictors actually killing and eating humans are quite rare.
Anacondas can reach lengths of 17 feet (5 meters). Some specimens may be as long as 36 feet (11 meters), but this is unusual. The anaconda is the heaviest snake in the world. A large individual anaconda might weigh 1,100 pounds (500 kilograms), but will usually top out at a few hundred pounds. Anacondas can measure more than 12 inches (30.5 centimeters) in diameter. Females typically outweigh males.
Green anacondas are found in Trinidad and tropical South America, east of the Andes, south to Bolivia and northern Paraguay.
They live in sluggish streams, rivers and adjacent swamps and marshes. While the anaconda frequents the water and is an excellent swimmer, it is very capable of moving on land and has limited climbing abilities.
During the rainy season, females in breeding condition give off pheromones that are tracked by nearby males who then approach. Her scent is an air-borne chemical emission and males come to her from all directions. Males flick their tongues in the air to pick up the chemical presence. The courtship period usually lasts about two months.
Anacondas use the water to escape from predators and when stalking prey
The extremely muscular anaconda is a constrictor and has teeth and powerful jaws that it utilizes to clench onto its prey. It grabs its victim and pulls it underwater, drowning the prey.
They typically feed on large rodents, tapirs, capybaras, deer, peccaries, fish, turtles, birds, sheep, dogs and aquatic reptiles. They have been known to occasionally prey on jaguars.
At the Smithsonian's National Zoo, they eat rats and rabbits about once a month.
Courtship and copulation usually take place in the water. The male presses his body to the female and rests his head on her neck. He flicks his tongue and his spurs become erect. The spurs rub against the female's vent region, which encourages her to copulate. As he presses his cloaca against hers, his spurs make a scratching sound. Copulation is complete when the female raises her cloaca to meet the male's. The male holds her against him tightly by wrapping his tail and lower body around her.
The gestation period lasts about six to seven months. Like other boa species, anacondas are ovoviviparous, or bear live young. Clutch and birth size are proportional to the female's size. A clutch could include up to 50 young ranging from 2 to 3 feet (0.6 to 0.9 meters) in length. The baby snakes can swim and hunt shortly after birth. They grow very rapidly reaching maturity at 3 to 4 years of age.
They have lived up to 30 years in human care.