The black mamba (Dendroaspis polylepis) is a species of extremely venomous snake, a member of the family Elapidae native to parts of sub-Saharan Africa. First formally described by Albert Günther in 1864, it is the second-longest venomous snake after the king cobra; mature specimens generally exceed 2 m (6 ft 7 in) and commonly grow to 3 m (9 ft 10 in). Specimens of 4. 3 to 4. 5 m (14 ft 1 in to 14 ft 9 in) have been reported. Its skin colour varies from grey to dark brown. Juvenile black mambas tend to be paler than adults and darken with age.