By Matt Patterson, Staff WriterHaunt the Zoo is one of the Oklahoma City Zoo’s biggest annual events, and now in its 31st year it promises to bring smiles, loads of candy and maybe a few scary moments along the way. Haunt the Zoo opens Sunday and will continue daily through Halloween from 6:30 to 8:30 p.m. While Haunt the Zoo has an established history, organizers add a little something extra every year to keep it fresh.Read more on NewsOK.com