JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. In this study laboratory experiments were conducted to test predictions of capture performance based on an understanding of the hydrodynamics of contrasting feeding modes (ram and suction feeding) and on an observed ecomorphological pattern among marine members of the temperate fish family Cottidae. Small-mouthed species that feed predominately on grasping prey (e.g., crabs, isopods, gastropods) were predicted to have low capture success on an elusive prey (shrimp) and to use kinematics more consistent with suction-feeding mechanisms; large-mouthed species that feed predominately on elusive prey (e.g., fishes, shrimp) were predicted to have high capture success in attacks on shrimp and to use ram-feeding kinematics. Laboratory experiments in which predators were videotaped in attacks on either hippolytid shrimp or cancrid crabs tested both the attack success and kinematic predictions.Small-mouthed cottid species had significantly lower attack success on shrimp (20-4 1% vs. 45-56%) than did large-mouthed cottids. Both groups had similar high success rates in attacks on crabs on a sand surface: 93-100% for small-mouthed species and 85-95% for large-mouthed species. Most small-mouthed cottids used attack kinematics more typical of suction feeding (e.g., shorter predator-prey distances and slower attack velocities) than did ram feeders. One small-mouthed species, Jordania zonope, used attack kinematics similar to those used by large-mouthed cottids in attacks on shrimp, and had higher capture success than other small-mouthed species, but had significantly lower capture success than large-mouthed species. All predators showed some ability to modify their attack kinematics when attacking prey with different escape tactics, but cottids showed little intraspecific variation in attack kinematics, in contrast to several recent studies of the strike mechanics of lower vertebrates.These results emphasize the importance of both mouth morphology and attack kinematics in determining interspecific differences in capture success and, perhaps, diet. The success of the simple predictions presented here provides hope that general predictions of foraging ecology may be derived from morphological patterns when the prey are treated not by their taxonomic affinities but by the functional demands they make on their predators. The study of the influence of form on the trophic biology of fishes has been an active area of researchfor over twenty years. The pioneering work of Keast and Webb (1966) demonstrated clear relationships between patterns of variation in mouth and locomotory structur...
SynopsisOne of the major goals of an ecomorphological analysis is to correlate patterns of interspecific differences in morphology with patterns of interspecific differences in ecology. Information derived from functional morphological studies may provide a mechanistic framework supporting the correlation, but the move from a correlational relationship to a causal relationship requires experimental evidence that the interspecific morphological differences create performance differences and therefore ecological differences . The goal of this study was to examine ecomorphological relationships in the diets of cottid fishes (Scorpaeniformes : Cottidae) from the northeastern Pacific by using functional classifications of predators (based on their mode of attack) and of prey (based on their anti-predator defenses) . The proposed ecomorphological relationships were tested by examining capture success among the cottids in attacks on prey with different escape abilities . As predicted on functional morphological grounds, both multivariate and univariate analyses indicated that the gravimetric importance of `elusive prey' (i .e . fishes, shrimp, mysids, and octopods) was greater in cottid species with a larger relative mouth size . Supporting a causal link between morphology and ecology, performance tests indicated that larger-mouthed cottids had significantly higher capture success on Heptacarpus shrimp than did smaller-mouthed species . As predicted, there were no differences in capture success among predators regardless of their attack style or ecomorphological patterns in attack on crabs (Cancer and Petrolisthes spp.) when the crabs were presented on a sand surface (i .e .`easy prey') . Several difficulties still exist when trying to apply a functional group approach to ecomorphology. These include the behavioral plasticity of the predators, the confounding factor of evolutionary history in identifying correlated ecomorphological features, multiple morphological solutions to common functional problems, the limitations of traditional dietary studies during extremes of prey abundance, and an inadequate understanding of the anti-predator defenses of most prey, including modifications that occur during ontogeny or in different habitats . IntroductionGlade or assemblage) use a common methodology .
SynopsisThe goal of an ecomorphological study is to understand the interactions between the morphology of organisms and their ecology. Both the morphology and the ecology presented by an organism are directly or indirectly under the influence of the environmental conditions that the organism experiences and its heritable composition. The development and interpretation of the central element of ecomorphological studies, the comparison between patterns of variation of morphological and ecological characters, depends heavily on the mechanistic framework provided by functional morphological and biomechanical studies. The cause-andeffect hypotheses derived from this comparison can be tested with performance trials . Ecomorphology forms an integral part of comparative biology, along with ecophysiology, behavioral ecology, and evolutionary ecology. Current issues in ecomorphological research that are addressed in this volume include application of a more functional approach to the choice of characters, integration of morphological, behavioral, and physiological information to address adaptation, and the expansion of spatial and temporal (ontogenetic and evolutionary) scales of ecomorphological questions . Future directions for ecomorphology include broadening the knowledge base, further integration of information from other disciplines, examination of the role of environmental and genetic factors in producing and maintaining ecological and morphological diversity, and application of ecomorphological insights to questions of community structure.
In contrast to the diets of other cottid fishes and most teleosts, the diet of Asemichthys taylori is dominated by gastropod mollusks. Access to this underused prey appears to be made possible by morphological speializations of the neurocanium that allow Asemichthys to puncture the shells of its prey during mastication. Unpunched, the shell and operculum act as a barrier to digestion; more than 40% of the unpunched gastropods emerged alive in the feces. Asemichthys adjusted its punching behavior in an apparently adaptive way; other prey lacking such barriers to digestion were rarely punched. The ability of some shelled invertebrates to avoid digestion may make them less desirable as prey for many fishes that cannot masticate this kind of prey. The ability of shelled mollusks to survive in the digestive tracts of vertebrates may provide a dispersal mechanism for otherwise sedentary species.
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