racer, name for several related swift, slender snakes, especially those of the genus Coluber. All of the racers are nonpoisonous, nonconstricting, day-active snakes. The black racer, C. constrictor, is easily confused with the constricting black rat snake, or pilot black snake ( Elaphe obsoleta ), which may account for its misleading Latin name. The black racer is satiny black, with a white patch on the chin, and may reach a length of 6 ft (180 cm) and a diameter of 11/2 in. (4 cm). It is found in E North America from Canada to Florida. It feeds primarily on small rodents, frogs, and young snakes, and is a valuable destroyer of vermin. One of the fastest-moving snakes, it has been clocked at over 31/2 mi (5.6 km) per hr. An aggressive snake, it will bite repeatedly if cornered; however, it can be tamed. The young, hatched from eggs, are pale gray, spotted with brown. The name is also applied to the related indigo snake ( Drymarchon corais ) and to some of the coachwhip snakes ( Masticophis ). The speckled racers are species of the genus Dryombius. All of the racers are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Squamata, family Colubridae.