Are plastic baits really plastic?

[Eesctom]

With all this talk about oil it was mentioned that the costs of plastics and fertilizer would be climbing along with oil prices. It made me wonder what exactly our "plastic" worms, and craws and other stuff are made of. Do they have some form of plastic in them that requires petroleum or are they just generically referred to as plastic baits but are made from something else? Just curious if anyone knows.