Rat snakes are a large, polyphyletic, group of snakes from the Colubrid subfamily Colubrinae. Many species tend to be very skittish and sometimes aggressive but the genus is nonvenomous and bites are usually superficial. A variety of species like Elaphe guttata guttata are known for the ease with which they are tamed and are common in the pet trade. There is considerable variation between different types of rat snake but most are medium to large, rodent eating snakes.
Previously most were assigned to the genus Elaphe but many have been since renamed. The validity of some genera is debatable but for the purpose of this article a more liberal taxonomic stance will be taken. Rat snakes have traditionally been divided into two groups, New World and Old World species.
Examples of snakes found in the Elaphe include:
New World rat snakes belong to the Colubrine tribe Lampropeltinae, and as such are closely related to Lampropeltis (milk snakes and king snakes), Pituophis ([snake]s, pine snakes and bull snakes), Rhinocheilus (longnose snakes), Arizona (glossy snakes) and Stilosoma (short-tailed snakes). The entire Lampropeltinid group is descended from Old World rat snakes that crossed the Bering Land Bridge sometime within the last twenty to thirty million years.
The New World rat snakes consist of the genera Bogertophis (Trans Pecos and Baja rat snakes), Elaphe (Corn snakes, Fox snakes and American rat snakes), Pseudelaphe (Central American rat snake) and Senticolis (Green rat snake).