Long-term memory of learning that a food is inedible was studied in Aplysia. Seven days after a single training session, animals retained significant memory, as measured by a number of parameters. A 2nd experiment demonstrated savings 3 weeks after 2 training sessions. Longterm memory was also found after training procedures were altered to resemble those more likely to occur in nature, such as training for only 10 min or training with ad-lib access to inedible food, with no experimenter intervention. The effects were determined of bilaterally sectioning the esophageal nerves that innervate the gut. Denervation of the gut blocked the ability to learn that food is inedible but did not affect memory after the task had already been learned.