Cooper, 45, who co-hosts CNN's New Year's Eve coverage with Griffin, 52, held the large, hairy spider for 15 seconds -- as if he could barely stand it -- on his syndicated show "Anderson" after refusing to drink pickle juice.
Moments earlier, Griffin held the arachnid as if it was nothing.
You can see the "Truth or Dare?" moment at tinyurl.com/Anderson-Cooper-Tarantula.
The episode, airing Friday, also includes a discussion of "ta-ta-toos," created by two women in Hollywood, Fla., who describe the products on their website as "temporary tattoos for your ta-tas."
The tattoos say things like "Bite Size," "Custom Built" and "Guess What? I'm Pregnant."
Anderson called the ta-ta-toos among the "ridiculous products" he has shown on his program.
During the discussion, Griffin said she had put a ta-ta-too on her body.
The program then showed a photo of a ta-ta-too that said "Let's Celebrate." It appeared not on her breasts but on her inner thigh -- "a place," she told Cooper, "I think you'll appreciate and a place you are invited to."
"It's a party down there," she said. "New Year's Eve every day."
Cooper is openly gay.
Griffin, who is straight, is a lesbian, gay, bisexual and transgender rights activist involved in causes such as same-sex marriage.
You can see their ta-ta-too conversation at tinyurl.com/Anderson-Cooper-Ta-Ta-Too.