some tarantulas eat snakes, namely the larger species of grammostola (achaeton, iheringi, grossa, alticeps, etc). these feed on young s.american rattlesnakes.
Watched a program ages ago , (in the 90's i think) about a Leblondi ..the camera crew spent ages creating a burrow with mini cameras set up inside... then a big female leblondi moved in... they were filming away only to witness a fer de lance crawl down the burrow! o_0 the leblondi nailed it and took a futher 17 hours to eat the lot lol! that snake got owned!