The digestive capacity of jellyfish has barely been studied because of the complexity of their life stage body-forms and sizes. To assess the digestive capacity in the changes from the benthic polyp-form to the pelagic stage in the cannonball jellyfish Stomolophus meleagris, we used fluorometric and spectrophotometric techniques for measuring the activity of trypsin, chymotrypsin, aminopeptidase, amylase, lipase, phosphatase acid, and alkaline. The findings showed that at all stages were able to digest proteins, carbohydrates, and lipids, but the digestive capacity differs between the benthic–pelagic stage and final development of the ephyrae, suggesting a shift in nutrient requirements. The digestive capacity indicated that polyps better assimilate carbohydrates and proteins. During the pelagic stage, a shift in the digestive capacity occurred, where 5-day ephyrae better assimilate proteins, while 15-day-old ephyrae were better with lipids and proteins and juvenile medusae with lipids. This is the first study to describe changes in the digestive capacity of cannonball jellyfish and can help identify ecological features of an important fishing resource with potential aquaculture interest. Different diets for polyps, ephyrae, and juvenile medusae must be considered if the species is cultivated.