Review of the Predators and Parasites of Stony Corals, with Special Reference to Symbiotic Prosobranch Gastropods

Abstract

Predators and parasites on the living tissues of stony (scleractinian) corals include bony and cartilaginous fishes, asteroids, crustaceans (cyclopoid copepods, cirripedes, and brachyuran crabs) , polychaetes, and gastropods (prosobranchs and nudibranchs). These are all facultative predators except the crustaceans and gastropods that are obligately associated (symbiotic) with and feed on their coral hosts. Such symbionts are known in four unrelated families of crustaceans (Xarifiidae, Asterocheridae, Balanidae, and Xanthidae) and four unr elated families of prosobranch gastropods (Architectonicidae, Epitoniidae, Ovulidae, and Coralliophilidae) . A fifth prosobranch family includes frequent but not obligate coral associates that are coral- and possibly also mollusk-feeders (Muricidae [Drupa, subgenus Drupella]). The eolid nudibranch genus Phestilla (Tergipedidae) includes the only so far identified opisthobranchs definitely symbiotic with corals. Most of the crustacean and molluscan symbionts live with hermatypic corals in the Indo-Pacific. Specificity to particular genera or families of corals is low, but the bright yellow, orange, or pink phases (species?) of the dendrophylliid ahermatypic coral Tubastraea are host to similarly colored prosobranchs C Epitonitlm" ) and a nudibranch (Phestilla melanobrachia) . Adapt ations for feeding on coelenterates are various, but in unrelated gastropod families similar specializations occur (cuticularized esophaguses and proboscises, ptenoglossate-like radular teeth, and total loss of radulae) . The most specialized of the coral-dwelling prosobranchs are the coralliophilids ( including Magiltus), parasites without radulae living both on and in coelenterates.