evidence: A member of the boa family, South America’s green anaconda is the heaviest snake in the world. Its cousin, the reticulated python, can reach slightly greater lengths, but the enormous girth of the anaconda makes it almost twice as heavy. Green anacondas can grow to more than 29 feet, weigh more than 550 pounds, and measure more than 12 inches in diameter. Females are significantly larger than males. [...] Anacondas live in swamps, marshes, and slow-moving streams, mainly in the tropical rain forests of the Amazon and Orinoco basins. They are cumbersome on land, but stealthy and sleek in the water. Their eyes and nasal openings are on top of their heads, allowing them to lay in wait for prey while remaining nearly completely submerged.