Effects of food deprivation upon time devoted to different behaviors in Aplysia fasciata were investigated. Time invested in mating, egg-laying, swimming, and movement in place was increased, and time spent immobile and crawling was decreased. Time of occurrence of behaviors was highly synchronized, but differed from that seen when food was available. Changes in behavior seem to be adaptive to conditions in which food is scarce: increased motility may lead to finding sites where food is present, while increased egg-laying and mating may ensure survival of progeny. Behavioral changes can be readily accounted for by removal of postingestive stimuli signaling satiation.