<Tr> <Td> Subfamily: </Td> <Td> Colubrinae </Td> </Tr> <Tr> <Td> Genus: </Td> <Td> Various </Td> </Tr> <P> Rat snakes (or ratsnakes) are members--along with kingsnakes, milk snakes, vine snakes and indigo snakes--of the subfamily Colubrinae of the family Colubridae . They are medium to large constrictors and are found throughout much of the Northern Hemisphere . They feed primarily on rodents and birds . With some species exceeding 3 m (10 ft) in total length, they can occupy top levels of some food chains . Many species make attractive and docile pets and one, the corn snake, is one of the most popular reptile pets in the world . Other species can be very skittish and sometimes aggressive, but bites are rarely serious . Like nearly all colubrids, rat snakes pose no threat to humans . Rat snakes were long thought to be completely nonvenomous, but recent studies have shown that some Old World species do possess small amounts of venom, though the amount is negligible relative to humans . </P> <P> Previously, most rat snakes were assigned to the genus Elaphe, but many have been since renamed following mitochondrial DNA analysis performed in 2002 . For the purpose of this article, names will be harmonized with the TIGR Database . </P>

What is the name of a black and white snake
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