The Black Mamba (Dendroaspis polylepis) is a venomous snake endemic to parts of sub-Saharan Africa. Scale color varies from grey to dark brown. Juvenile black mambas tend to be paler than adults and darken with age. The black mamba gets its name for the black interior of its mouth, which it opens when feeling threatened. It is the longest species of venomous snake indigenous to the African continent and the second longest in the world; mature specimens generally exceed 2 meters (6.6 ft) and commonly attain 3 meters (9.8 ft). Specimens of 4.3 to 4.5 meters (14.1 to 14.8 ft) have been reported. Only the king cobra of South and Southeast Asia is longer.
Although the three other mamba species are tree-dwelling snakes, and juvenile black mambas frequently climb trees, an adult black mamba is not generally arboreal, preferring lairs in terrestrial habitats in a range of terrains. These include savannah, woodlands, rocky slopes and in some regions dense forest. It is diurnal and chiefly an ambush predator, known to prey on hyrax, bushbabies and other small mammals as well as birds. The largest specimens can even swallow a dik-dik. It is also a pursuit predator; in this it resembles some other long, speedy, highly-venomous species with well-developed vision. Over suitable surfaces it is possibly the speediest species of snake, capable of at least 11 km/h (6.8 mph) over short distances. Adult mambas have few natural predators.
In a threat display, the mamba usually opens its inky black mouth, spreads the ribs along its neck similarly to a cobra, and sometimes hisses. It is capable of striking at considerable range and occasionally may deliver a series of bites in rapid succession. Its venom is primarily composed of potent neurotoxins that may cause fast onset of symptoms. Despite its reputation for being formidable and highly aggressive, like most snakes, it usually attempts to flee from humans unless threatened or cornered. Not being proximal to humans, bites from the black mamba are not frequent.
The black mamba's neurotoxic venom can kill a human in as little as 20 minutes, but may take a few hours, and is nearly always fatal without treatment. Bite symptoms include numbness, tingling, paralysis, and respiratory failure, ultimately leading to death without antivenom. Its venom is extremely potent, and only about 20 milligrams are required to kill an adult human (based on rodent LD50 values), with the average bite from a black mamba yielding 100-120 milligrams of venom--enough to kill up to six adult humans. It is also the only species of snake known to have killed an adult elephant. Black mambas are shy and usual avoid people, but can be very defensive if confronted.