Previous research on sensitization in "Aplysia" was based entirely on unnatural noxious stimuli, usually electric shock, until our laboratory found that a natural noxious stimulus, a single sublethal lobster attack, causes short-term sensitization. We here extend that finding by demonstrating that multiple lobster attacks induce long-term sensitization (=24 h) as well as similar, although not identical, neuronal correlates as observed after electric shock. Together these findings establish long- and short-term sensitization caused by sublethal predator attack as a natural equivalent to sensitization caused by artificial stimuli.