Three collections of common soft corals were made for an ichthyotoxicity study. Morphological features relating to structural defence against fish predation were also assessed. The first set of samples, comprised of 68 specimens derived from 16 genera and 57 species was collected from Britomart Reef, Davies Reef, Slashers Reef and Orpheus Island between August and October, 1980. The second set of 36 specimens derived from 9 genera and 34 species, was collected from Britomart Reef, Rib Reef and Myrmidon Reef between August and October 1982. A final set of samples was collected at Lizard Island and was comprised of 67 specimens derived from 16 genera and 55 species.Initially, 16 attributes (each with between 2 and 4 levels) presumed to be of adaptive significance in morphological defence against fish were recorded for 68 alcyonacean corals from a wide range of species. These characters fell into the more general categories of: gross colony form (encrusting or erect); colony texture (including sharpness or spikiness, hardness, flexibility, and penetrability); presence of mucus; color; polyp retractility; sclerite morphology and distribution (including density of sclerite packing, length, sharpness, placement, and orientation within the colony - assessed microscopically). The soft coral species used in this study were then categorised from most toxic to least toxic (1-9) based on previous ichthyotoxicity studies of behaviour and mortality levels in test fish. A second set of observations concentrated on 28 specimens of the genus Sinularia and 28 specimens from the family Nephtheidae, which vary widely in both their morphological and ichthyotoxic characteristics. A more restricted and clearly defined set of morphological characters were considered: consistency of exposed colony parts; superficial armament of the polypary; mineralization of coenenchymal mass; anthocodial armament; and polyp retractility. In this study, soft coral species were classified as toxic or non-toxic based on relative mortality levels of test fish after 12 hours.
