green anaconda, common name for what are generally considered to be two species of nonvenomous semiaquatic boa (family Boidae) native to South America. Green anacondas are known for their immense size, some recorded specimens measuring as long as 9 meters (30 feet) and weighing more than 250 kg (550 pounds). They are some of the longest snakes in the world, and they are the largest by weight. The term green anaconda refers to Eunectes akayima, the northern green anaconda, and E. murinus, the southern green anaconda, though some dispute this distinction (see below). While additional species of anaconda are recognized, ...(100 of 1081 words) Access the full article Help support true facts by becoming a member. Subscribe today!