Black Mamba

Not only is this reptile lethally venomous, it can also grow up to 14 feet long, making it Africa’s longest venomous snake—and a fast-moving one at that (it can move at speeds of 12.5 miles an hour). Their name refers not to their skin color (which tends to be gray) but the inside of their mouths, which is more of a blue-black color. If you see the inside of their mouths, it may be too late: these animals inject a huge amount of nuero- and cardiotoxin each time they strike, causing death within 20 minutes.