Hermit crabs (Decapoda: Anomura) are typically omnivorous and are common on Caribbean coral reefs. Sponges are sessile, fleshy, and high in protein and energy content, yet hermit crabs do not appear to prey on them. Assays were performed with the Caribbean reef hermit crab Paguristes punticeps to determine whether secondary metabolites or skeletal elements of Caribbean sponges that were incorporated into artificial foods affected feeding. Of 30 sponge species assayed, 26 (87 %) yielded organic extracts that deterred feedlng by P punticeps. There was substantial interspecific and intraspecific vanabllity in patterns of chemical deterrence. Sponges of the families Axinellidae, Agelasidae, Aplysinidae, Aplysinellidae, and Thorectidae typically yielded deterrent extracts. Three common sponge species, Mycale laevis, Callyspongla vaginalis, and Niphates erecta, were consistently non-deterrent, while other species, including Spheciospongja othella, Chondrilla nucula, Callyspongia plicifera. Niphates digitalis, and Xestospongia muta, were variably deterrent. These results are in general agreement with those of a previous survey of Caribbean sponge chemical defenses using the common reef fish Thalassoma bifasciatum. However, some results differed: Geodia neptuni and Iotrochota birotulata were consistently palatable to T. bifasciatum, but were deterrent to P. punticeps. Several species that were consistently deterrent to 7 bifasciatum were variably deterrent to P punticeps, including Aplysina caulifornus, Aplysina fulva, Ircinia strobilina, Amphimedon compressa, and Mycale laxjssima. Neither spicules (from Agelas clathrodes, Ectyoplasia feros, and Xestospongia muta) nor splculated spongin skeleton (from A. clathrodes and X. muta) deterred feeding by P, punticeps. Spicules and spiculated spongin were similarly non-deterrent to the fish T bifasciatum in a previous survey. The results of this study further suggest that chemical defenses are important in the ecology of Caribbean sponges, while skeletal components do not serve an antipredatory function.

Sea stars are dominant predators in many manne habitats, and spongivory by sea stars has been documented from polar seas to the tropics. Feeding assays of whole tissue and artificial foods containing organic extracts, spicules, and spiculated skeleton of sponges were performed with the Caribbean sea stars Ech~naster echinophorus (from the Bahamas) and Echinaster sentus (from Florida, USA) to determine whether sponge secondary metabolites or skeletal constituents affect feeding by sea stars. Whole tissue assays of 6 species of mangrove sponges yielded similar preference hierarchies for both sea star species: for E. echinophorus, Tedania ignis = Haliclona hogarthi? Ircinia felix = Dysidea etheria > Chondrilla nucula = Chondrosia collectn'x; for E. sentus. T. ignis = H. hogarthi > I. feliu = D. etheria = C. nucula = C. collectriu. Whole tissue assays of 5 specles of reef sponges yielded identical hierarchies for both E echinophorus and E sentus: Geodia neptuni > Callyspongia vaginaljs > Amphimedon compressa = Ectyoplasia ferox = Agelas clathrodes Crude organic extracts of the same 6 mangrove sponge specles were assayed, and only the crude organic extracts of Dysidea etheria deterred feeding by E. echinophorus. Extracts of I. felix, which consistently deterred both fishes and hermit crabs in previous studies, did not deter E. echinophorus. Extracts of the same reef sponge species were assayed, and only A. clathrodes, E. ferox, and A. compressa deterred feeding by E. echinophorus. In whole tissue assays with E. sentus of chemically non-defended species (sponges that ylelded organic extracts palatable to E. echinophorus) from both reef and mangrove habitats, all specles were consistently preferred over C. nucula. The preferences of E, sentus for chemically nondefended species did not correlate with sponge nutritional or skeletal content, suggesting that other characteristics of these sponges influence sea star preferences. Spicules from 5 species of reef sponges (G. neptuni. C. vaginalis, A. clathrodes, E. ferox, and A. compressa) and 3 species of mangrove sponges ( T ignis, H. hogarthi, and C. nucula), and whole sponge skeleton from 4 species of mangrove sponges ( T ignis. I. felix, C. nucula, and C. collectrix) did not deter feeding by E. echinophorus. These results, when considered with the data from previous studies employing fishes and hermit crab assays, further illustrate the importance of secondary metabolites as antipredatory defenses for Caribbean sponges.