Contrary to what its name would suggest, black mambas are actually brownish in color, ranging from olive to greyish tones, with paler bellies. “They are named for the coloration of the inside of their mouths, which is a deep, inky black,” explained Viernum. “Similar to cottonmouths, when threatened a mamba will open its mouth to show the black lining as a warning signal.”
Black mambas have coffin-shaped heads and are lithe, athletic snakes. According to National Geographic, they can grow to be 14 feet long (4.25 meters), though their average length is around 8 feet (2.4 m). These giants can live up to 11 years in the wild.