Symbiotic Polychaetes: Review of known species

Although there have been numerous isolated studies and reports of symbiotic relationships of polychaetes and other marine animals, the only previous attempt to provide an overview of these phenomena among the polychaetes comes from the 1950s, with no more than 70 species of symbionts being very briefly treated. Based on the available literature and on our own field observations, we compiled a list of the mentions of symbiotic polychaetes known to date. Thus, the present review includes 292 species of commensal polychaetes from 28 families involved in 713 relationships and 81 species of parasitic polychaetes from 13 families involved in 253 relationships. When possible, the main characteristic features of symbiotic polychaetes and their relationships are discussed. Among them, we include systematic accounts, distribution within host groups, host specificity, intra-host distribution, location on the host, infestation prevalence and intensity, and morphological, behavioural and/or physiological and reproductive adaptations. When appropriate, the possible directions for further research are also indicated.