An anaconda is one of the largest snakes in the world, living in the swamps and rivers of South America's Amazon rainforest. These massive constrictors can grow over 20 feet long and weigh more than 500 pounds. The green anaconda, the most famous species, has olive-colored skin with dark spots that help it blend into murky water.

Anacondas are constrictors, meaning they squeeze their prey rather than using venom. When an anaconda catches an animal like a capybara or caiman, it coils its powerful body around the victim and squeezes until the animal can't breathe. Then the snake swallows its meal whole, which can take hours because the anaconda's jaw can unhinge to stretch around large prey.

These snakes spend most of their time in water, where their bulk becomes an advantage rather than a burden. On land, anacondas move slowly and awkwardly, but in rivers and swamps they're swift and graceful hunters. Female anacondas are much larger than males and give birth to live baby snakes rather than laying eggs.

Today, people sometimes use “anaconda” to describe anything enormous and serpentine.