Trophic ecology of terapontid fishes (Pisces: Terapontidae): the role of morphology and ontogeny

With the covariation between fish form and function of long-standing interest to fish biologists, ecomorphological research provides a framework for assessing the interaction between the morphology of an organism and their ecology. Whereas ecomorphological studies of Australian fishes are rare, the terapontid grunters are an ideal candidate for study because of their diversity of dietary habits. We examined the morphological correlates of the diet of 21 species of northern Australia's terapontids and their constituent ontogenetic trophic units. Preliminary analyses focusing on morphology identified the role of allometric growth - in characters such as intestinal length, maxilla length and mouth width - as driving considerable ontogenetic divergence in interspecific morphological trajectories. A significant relationship was identified between diet and morphology across species, although morphology explained only half of the observed dietary variation. Body size, and its relationship to allometric development of several morphological parameters, appears to constrain the trophic habits expressed by many terapontids at different life-history stages. Many of the diet-morphology relationships evident within the Terapontidae parallel those seen in other studies, providing substantial corroboration for the ecomorphological approach. This demonstrates that selective pressures have driven morphology in terapontids to converge morphologically with other ecologically comparable fishes across the globe.