Biomechanics and Evolution of Fish Feeding

Fish feeding biology is a well-established model system for the study of biomechanics, physiology, and comparative diversity. In this lab, we are developing biomechanical models of complex feeding movements in coral reef fishes to test new hypotheses for the mechanism of jaw opening and upper jaw protrusion in fishes. Models include four mechanisms of feeding mechanics in seven labrid fish species (Westneat 1990; 1994), the highlight of which is the spectacular jaw mechanism of the sling-jaw wrasse (Westneat 1991). In addition to proposing novel feeding mechanisms, this research allowed an evolutionary analysis of biomechanics in fishes (Westneat, 1995).

Recently we have continued to discover new feeding mechanisms in fishes and develop new hypotheses of biomechanical evolution. We are analyzing trophic morphology and function throughout the vast diversity of labrid fishes. We will develop an ecomorphological comparison across clades by mapping biomechanical features of feeding throughout the phylogeny of the Labridae. Research projects on the mechanics of feeding in wrasses, parrotfishes, and other biting taxa show that specialization for a forceful bite is widespread among fishes and is associated with key jaw design features and a high diversity of motor control patterns. Studies of parrotfish feeding (Alfaro and Westneat, 1999) contrasted the neuromotor patterns of two parrotfishes with patterns of suction feeding, finding that the motor basis for the herbivorous bite of parrotfishes is unique among fishes. Further, we find that motor control and motion of biting mechanisms is modulated to a much greater degree than suction feeding studies have suggested (Alfaro et al., 2001). Combining biomechanical models with studies of behavior and modulation in motor control will make the key link between neural, structural, mechanical and behavioral levels that this model system has promised for many years.