Cryptobenthic fishes and co-inhabiting shrimps associated with the mushroom coral Heliofungia actiniformis (Fungiidae) in the Davao Gulf, Philippines

摘要

The free-living solitary mushroom coral Heliofungia actiniformis resembles sea anemones by having large, fleshy polyps with long tentacles, which provide shelter to symbiotic organisms. Commensal shrimps are well studied, but little is known about associated fish fauna. Therefore, the associated fauna of 118 coral polyps of H. actiniformis was examined at a depth range of 4-28 m in the Davao Gulf, Philippines. The distribution of associated fishes and symbiotic invertebrates highly depended on the size of the coral host: Large corals polyps (> 18 cm) supported co-inhabiting fishes and commensal shrimps, medium-sized polyps (diameter 5-18 cm) hosted either fishes or shrimps, and small coral polyps ( 5 cm) were uninhabited. Fifteen fish species, representing the Apogonidae, Gobiidae, Labridae, and Pomacentridae, were found. Among these, the gobies Eviota lachdeberei and E. rubriceps, and the labrid Oxycheilius celebicus were most common, making up for 77 % of all fishes encountered. Total length of the fish ranged from 1 to 6 cm covering adult gobies and juveniles of the other families. Four species of commensal shrimps were hosted by the coral polyps. This study further constitutes the first record of brittle stars of the genus Ophiothrix (Echinodermata: Ophiuroidea) living among tentacles of H. actiniformis.