Survey of causal factors underlying the expression of animal behavior, organized around common problems organisms need to solve, such as finding food, avoiding predation, determining when and with whom to reproduce, communicating with other organisms, and extracting information from the environment. These factors are examined from an integrative perspective that includes neurobiology, endocrinology, sensory physiology, genetics, developmental biology, and functional morphology. Prerequisite: Biology 202L, 202LA, or 203L.