Palatability and Physical and Chemical Defenses in Five Annelid Polychaetes from Tropical Brazilian Beaches.

AbstractAlthough researchers have examined numerous marine organisms' compensatory characteristics to minimize predation pressure, few have investigated the defensive mechanisms of polychaetes, despite their diversity. Thus, our study's aim was to evaluate the palatability and defensive strategies, both chemical and structural, in the polychaetes , , , , and sp. Another twofold aim was to determine, by comparing our results with the literature, any latitudinal difference in the defensive strategies of and to assess defensive mechanisms and palatability in relation to individuals' mobility, overtness, body regionalization, and color. Specimens were collected at Boa Viagem and Itaipu Beaches in Niterói, Rio de Janeiro, Brazil. In assays, a generalist consumer, the hermit crab , was used to evaluate palatability and defenses. In palatability assays of live tissue of the polychaetes, consumers were offered a fresh piece of each polychaete to gauge their acceptance or rejection; in artificial food assays to test extracts of the polychaetes, artificial bait containing extracts of the polychaetes was offered to crabs to identify any chemical defense. Although the extracts of , , (, opercular crown), and sp. were not palatable to the consumers, extracts of and (, body) were. Moreover, the opercular crown of and the branchial crown of showed evidence of structural and chemical defenses. The results corroborate past findings, suggesting no latitudinal variation in the defensive strategies of . In general, less motile and more exposed species, aposematic or dark in color, exhibited greater investment in defensive strategies and unpalatability.