Ecomorphology of Feeding in Coral Reef Fishes

Once an observer gets past the stunning coloration, surely no feature inspires wonder in coral reef fishes so much as their morphological diversity. From large-mouthed groupers, to beaked parrot fish, barbeled goatfish, long-snouted trumpet fish, snaggletoothed tusk fish, tube-mouthed planktivores, and fatlipped sweet lips, coral reef fishes display a dazzling array of feeding structures. And, even the most casual fish watcher quickly gets a sense that this diversity means something, that fish form is related to what the animals eat. Clearly there is something to this impression, but just how are head and body morphology connected to prey choice? Are we really able to predict what a reef fish eats from studying its jaws and teeth? What are the major axes of diversification that are seen in reef fishes? Which morphological and ecological trophic types show the most common convergence? What ecological insights into reef processes have been gained from consideration of the functional design of fish feeding mechanisms? In this chapter we explore the relationship between fish anatomy and feeding habits. Our overall goal is to show how an understanding of the functional morphology of fish feeding mechanisms can be a powerful tool when considering several ecological issues in coral reef fish biology. We have attempted to identify generalities, the major patterns that seem to cut across phylogenetic and geographic boundaries. We begin by constructing a rationale for how functional morphology can be used to enhance our insight into some long-standing ecological questions. We then review the fundamental mechanical issues associated with feeding in fishes, and the basic design features of the head that are involved in prey capture and prey processing. This sets the stage for a discussion of how the mechanical properties of fish feeding systems have been modified during reef fish diversification. With this background, we consider some of the major conclusions that have been drawn from studies of reef fish feeding ecomorphology. Because of space constraints we discuss only briefly the role of sensory modalities—vision, olfaction, electroreception, and hearing—but these are also significant and diverse elements of the feeding arsenal of coral reef fishes and entire review chapters could be written on each one.