Hello and thanks for researching this interesting question!
The Colubrid (or Colubrine) family of snakes, including garter and ribbon snakes, brown snakes, kingsnakes and milksnakes, rat and corn snakes, pine and gopher snakes, and hog-nosed snakes, comprise more than 1500 species in all! They are found all around the world and across the entire U.S..
Many of these snakes are considered harmless (they often feed by constricting their prey), but some (garter snakes included!) do have hollow teeth and toxic salivary glands located in the rear of the mouth, and can be considered "mildly venomous" (garter snakes have reportedly caused allergic reactions in some sensitive people).
These various snakes eat fish, rodents, amphibians, worms and insects!
Their care instructions are as varied as their appearance...so a specific study should be made in regards to acquiring any individual from this family.
Here is just one general link site that has photos and other information about the Colubrids:
http://www.szgdocent.org/resource/rr/c-colbrid.htm
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Retired Veterinary Technician
Lhasa,Shih Tzu Breeder/ B.A.Neurophysiology & Animal Behavior/I use plain English!