Assessing the antipredatory defensive strategies of Caribbean non-scleractinian zoantharians (Cnidaria): is the sting the only thing?
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The relative importance of chemical, nematocyst, and nutritional defenses was examined for 18 species of Caribbean sea anemones (actinarians), zoanthids, and mushroom polyps (corallimorpharians) from the Florida Keys and the Bahamas Islands, 2008–2010. Feeding assays were performed using the fish Thalassoma bifasciatum with artificial foods containing crude organic extracts of cnidarian tissues. A novel behavioral assay using brine shrimp nauplii was used to assess nematocyst defenses. The nutritional quality of cnidarian tissues was examined using bomb calorimetry and soluble protein assays. In general, actinarians invested in nematocyst defenses, zoanthids in either nematocyst or chemical defenses, and corallimorpharians lacked both, except for 1 of 3 species that was chemically defended. Relative to other coral reef invertebrates, cnidarian tissues had similar caloric values but lower soluble protein concentrations. Trade-offs between chemical and nematocyst defenses were observed for 65% of species, while habitat and behavior provided a likely explanation for undefended species.
KeywordsCoral Reef Reef Fish Chemical Defense Soluble Protein Content Defensive Mechanism
This study was funded by grants from the National Undersea Research Program at UNCW (NOAA NA96RU-0260) and from the National Science Foundation Biological Oceanography Program (OCE-0550468, OCE-1029515), as well as the UNCW Brauer Fellowship Award. Thanks to Michael Echevarria, Tim Henkel, Wai Leong, Tiffany Lewis, Tse-Lynn Loh, Dr. Susanna López-Legentil, Steven McMurray, Andrew Miller, Jan Vicente, and Colin Foord for assistance in collecting specimens. We would also like to thank the anonymous reviewers who helped to improve this manuscript.
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