Biodiversity is a concept that covers a lot of issues that can elucidate diversity-related functional roles to understand ecological ecosystem functioning. Biodiversity can shape ecosystem structure and functioning especially if we focus on predator-prey interactions. Moreover, the mechanisms governing prey-predator relationships will shape the emergent food web structure just as individuals’ characteristics determine the emergent demographic structure of a population. We determined the trophic ecology of fish species in the eastern English Channel by combining gut-content and geomorphometric analyses. We inferred the mechanisms of resource utilisation by Atlantic seabass and plaice by coupling measured geomorphometric determinants of prey-predator interaction with the observed diet in order to determine functional relationships between fish morphology and diet. Results were then analyzed using cluster and correspondence analyses to describe correlation between ecomorphological and dietary matrices. Such empirically determined allometries will consequently be used to simplify the description of predator-prey interactions by collapsing its dimensions to few more relevant morphometric characteristics per species.