Anatomy: Like all snakes, anacondas are cold-blooded; they are the same temperature as the environment. They continue to grow all their lives, getting bigger and bigger each year. The longest anaconda ever found was 37.5 feet (11.4 m) long, there are probably even bigger anacondas that have not been seen. Anacondas are greenish-brown with a double row of black oval spots on the back and smaller white markings on the sides. Their scaly skin glistens but is dry is to the touch. The nostrils are on top of the snout, letting the snake breathe easily when it is in the water. It smells with its tongue. It has no fangs.

Hunting and Diet: Anacondas are carnivores (meat-eaters). They mostly hunt at night (they are nocturnal). Anacondas kill by constricting (squeezing) the prey until it can no longer breathe. Sometimes they drown the prey. Like all snakes, they swallow the prey whole, head first. The anaconda's top and bottom jaws are attached to each other with stretchy ligaments, which let the snake swallow animals wider than itself. Snakes don't chew their food, they digest it with very strong acids in the snake's stomach. Anacondas eat pigs, deer, caiman (a type of crocodilian), birds, fish, rodents (like the capybara and agouti), and other animals. After eating a large animal, the anaconda needs no food for a long time, and rests for weeks. The young (called neonates) can care for themselves soon after birth, including hunting (but are pretty much defenseless against large predators). They eat small rodents (like rats and mice), baby birds, frogs and small fish.

Classifcation: Kingdom Animalia, Phylum Chordata, Class Reptilia, Order Squamata (lizards and snakes), Suborder Serpentes, Family Boidae (constrictors), Genus Eunectes, Species murinus.