MEPS 127:195-211 (1995)  -  doi:10.3354/meps127195

Defenses of Caribbean sponges against predatory reef fish. II. Spicules, tissue toughness, and nutritional quality

Chanas B, Pawlik JR

Laboratory and field feeding experiments were conducted to assess the palatability to predatory reef fish of prepared foods containing natural concentrations of glass spicules from 8 species of Caribbean reef sponges. Sponge species with high concentrations of spicules in their tissues, and with variable spicule morphologies, were chosen for the experiments. The presence of spicules did not alter food palatability relative to controls for any of the sponges tested. Analyses of ash content, tensile strength, protein, carbohydrate, and lipid content, and total energy content were conducted on tissue samples from 71 species of Caribbean demosponges from reef, mangrove, and grassbed habitats, and compared to previously reported data on the chemical defenses of the same species. There was no evidence to support the hypothesis that sponge species with palatable extracts have higher concentrations of inorganic structural elements, as measured by the mean ash content of their tissues. In addition, the tissues of palatable sponges were not different from those of chemically deterrent species with regard to mean tensile strength, protein content, carbohydrate content, and total energy content, but the tissues of chemically defended species did have a higher mean lipid content than those of palatable species. Sponges that lack chemical antipredatory defenses do not appear to compensate with structural or nutritional defenses, but may instead direct energy otherwise used for the production and storage of secondary metabolites to increased growth and reproduction.

Sponge . Defense . Caribbean . Coral reef . Predation . Spicules . Nutritional value . Toughness

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