Stress can alter adaptive behaviors and also either enhance or diminish learning, memory formation, and/or memory recall. We focus our studies on how environmentally relevant stressors such as predator detection, crowding, and low concentrations of environmental Ca2+ alter learning and long-term memory (LTM) formation in the pond snail, Lymnaea stagnalis. We specifically focus on operant conditioning of aerial respiration and whether or not LTM forms following the acquisition of the learned event. In addition, we have begun to assay the consequences of combing different stressors together. Our conclusion so far is that the effects of different combinations of stressors on LTM formation are an emergent property and thus can only be ascertained following direct experimentation. We also examine the strain differences in Lymnaea that allow or cause isolated populations to possess different heritable capabilities, as manifested by differing abilities to form LTM.