Specialized morphology corresponds to a generalist diet: linking form and function in smashing mantis shrimp crustaceans
Many animals are considered to be specialists because they have feeding structures that are fine-tuned for consuming specific prey. For example, “smasher” mantis shrimp have highly specialized predatory appendages that generate forceful strikes to break apart hard-shelled prey. Anecdotal observations suggest, however, that the diet of smashers may include soft-bodied prey as well. Our goal was to examine the diet breadth of the smasher mantis shrimp, Neogonodactylus bredini, to determine whether it has a narrow diet of hard-shelled prey. We combined studies of prey abundance, feeding behavior, and stable isotope analyses of diet in both seagrass and coral rubble to determine if N. bredini’s diet was consistent across different habitat types. The abundances of hard-shelled and soft-bodied prey varied between habitats. In feeding experiments, N. bredini consumed both prey types. N. bredini consumed a range of different prey in the field as well and, unexpectedly, the stable isotope analysis demonstrated that soft-bodied prey comprised a large proportion (29–53 %) of the diet in both habitats. Using a Bayesian mixing model framework (MixSIAR), we found that this result held even when we used uninformative, or generalist, priors and informative priors reflecting a specialist diet on hard-shelled prey and prey abundances in the field. Thus, contrary to expectation, the specialized feeding morphology of N. bredini corresponds to a broad diet of both hard-shelled and soft-bodied prey. Using multiple lines of study to describe the natural diets of other presumed specialists may demonstrate that specialized morphology often broadens rather than narrows diet breadth.
KeywordsStomatopoda Stable isotopes Bayesian mixing model Raptorial appendage Feeding ecology
We thank E. Gonzalez-Ulloa, F. Guerra, J. Morales, E. Staaterman, G. Thomas, T. Claverie, S. N. Patek, J. R. A. Taylor, R. L. Caldwell, D. Desmet, J. Hassen, A. Pickard, M. Limm, and M. E. Power and for assistance with study design, field work, and sample analysis. Fieldwork would not have been possible without I. Grenald and the staff at the Smithsonian Tropical Research Institute’s Galeta Point Marine Laboratory. We also thank S. Beissinger, R. L. Caldwell, J. Harris, S. Mambelli, A. Roddy, B. X. Semmens, M. I. Shuldman, T. S. Tunstall, P. C. Wainwright, and especially S. N. Patek for insightful discussion about data analysis and for comments on this manuscript. We thank J. Wortham and two anonymous reviewers for thoughtful comments on the manuscript. We are grateful for the use of the photograph in Fig. 1 from R. L. Caldwell. We thank the Autoridad Nacional del Ambiente in Panama for granting permits for this research (spring SEX/A-88-08, fall SEX/A-133-08). Research was funded by the American Museum of Natural History Lerner-Gray Fund, the Berkeley and National Sigma Xi Scientific Honors Society Grants-In-Aid-of-Research, the Fulbright Student Research Grant, the Society of Integrative and Comparative Biology Grants-In-Aid-of-Research, the Smithsonian Tropical Research Institute’s Short-Term Fellowship Award, the UC Berkeley Department of Integrative Biology Endowment, and the UC Museum of Paleontology Graduate Student Research Award (all awards to M. S. deVries), and a National Science Foundation Integrative Organismal Systems Grant (#1014573 to S. N. Patek). B.C. Stock was supported by the National Science Foundation Graduate Research Fellowship (DGE-1144086). Manuscript preparation was funded by the Phi Beta Kappa Graduate Fellowship (to M. S. deVries).
Author contribution statement
MSdV formulated the original idea. MSdV and JHC conceived and designed experiments. MSdV performed experiments. MSdV and TED performed stable isotope analyses. BCS analyzed the stable isotope data and MSdV analyzed the other datasets. GRG provided significant input on data analysis and interpretation. MSdV wrote the manuscript but BCS wrote the stable isotope statistical analysis methods and results. All authors contributed substantially to the interpretation of results and by giving critical conceptual and editorial advice.
Compliance with ethical standards
All applicable institutional and/or national guidelines for the care and use of invertebrates were followed.
Conflict of interest
The authors declare that they have no conflict of interest.
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