Whales are important model systems for understanding the physiological and ecological consequences of extreme body size. However, whales are also some of the most difficult animals to study because their large size largely precludes experimental studies under controlled conditions. Here we review a wide range of morphological studies that enable greater inference of physiological processes. In particular, we focus on baleen whales that exhibit extensive diving and foraging adaptations. Using morphological data, we 1) explore the biomechanics and sensory physiology of lunge feeding rorqual whales (Balaenopteridae), 2) determine the effects of scale and diving pressures on the circulatory physiology of fin whales, and 3) understand the adaptations of the cetacean respiratory system that facilitate a fully aquatic life history. These studies underscore the value of understanding functional morphology in animals that cannot be studied using traditional laboratory techniques.
