Our research includes both laboratory and field experiments on the behavioral and sensory capabilities of fish larvae. Much of it involves frame-by-frame motion analysis of video taped experiments. This approach has led to important insights into the change in vulnerability of larvae to predators during early life. We combine the behavioral approach with detailed studies of changing sensory and locomotor morphology to understand how behavior may be constrained. We also study the effects of environmental variables (e.g., temperature and salinity) on a larva's capabilities. We incorporate field experiments to form ecological interpretations for the laboratory results. Our research has now expanded to include assessment of sublethal effects of pollutants and their ecological interpretation.