Abstract
Rocky reefs of the northern Colombian Pacific (Chocó) are diverse ecosystems that are poorly studied. Echinoderms are one of the principal groups in these ecosystems with associations to different species, including benthic organisms in which they live and other species that use them as hosts. These relationships include fishes, sponges, seaweeds, cnidarians, polychaetes, bryozoans, crustaceans, mollusks, and other echinoderms. For this area, 22 associations were registered, including commensalism, epibionts and parasitism. This work constitutes the first report for the associations of Eucidaris thouarsii with Suberites aff. ficus, E. thouarsii with Ophiothela mirabilis, and Holothuria (Thymiosicia) impatiens with Encheliophis vermicularis. Associations of Pentaceraster cumingi with Zenopontonia soror, and Ophionereis annulata with Malmgreniella cf. variegata are new records for Colombia. This work also expands the range of hosts previously described for Ophiothela mirabilis and expands the distribution of the association between Diadema mexicanum and Echineulima cf. robusta.