Its back has a shiny tinge to it, and solidly colored in bluish, greenish, or sometimes, grayish shades. As their name suggests, they can move very fast, at a speed of about 7 km or 4.3 miles per hour. Green snakes with lethal venom include the African green mamba, palm pit viper, green parrot snakes, African bush viper, boomslangs, and two-striped forest pit vipers. Almost every serpentine family contains some green-colored snakes. The only U.S. venomous snakes that can have a greenish hue are cottonmouths and Mojave rattlesnakes. They are found in large parts of North America. In Ontario, it ranks among the province’s largest snakes. Some snakes are dangerous because of the speed or ferocity of their attacks, others because of how common and widespread they are, and still others because their toxins are so deadly. Other snakes with black coloration include the black pine snake, black racer, kingsnake, coachwhip, and eastern hognose. Snakes may be blue-black over the entire body or may have red, reddish-orange, or cream coloration on the chin, throat or cheeks. Here is a list of the most dangerous snakes in the world Scales of the body are smooth. Blue racer snakes, commonly known as eastern racers are subspecies of Coluber constrictor – a nonvenomous species of colubrid snakes. The blue racer is a large snake, ranging between four to six feet in length.