Body size is often considered a ‘master trait’ because it affects almost all vital rates, including growth and metabolism. As metabolic rates of organisms influence many ecological processes, much research interest has been placed on understanding how metabolic rate scales with body size. My PhD investigates the factors that could explain the variations in the relationship between metabolic rate and body size. Using both aquatic and terrestrial organisms, I am investigating the role of body shape and surface area, and ecological factors such as lifestyle, in explaining variation in such scaling relationships. My work will test existing hypotheses and aim to clarify the mechanisms that underpin the patterns found in the empirical data. I am currently engaged with work on insects as well as jellyfish and cephalopods.