Sea Fan

Large sea fans — gorgonian corals with fan-shaped colonies that can exceed a metre across — colonise the vertical and overhanging faces of Rock Garden's boulders, orienting their branches perpendicular to the current to maximise plankton capture. They are slow-growing colonial organisms, with large individuals representing decades of growth, and serve as habitat for pygmy seahorses, long-nosed hawkfish, and crinoids that drape their feeding arms across the fan surface. Their vivid colouration is produced by photosynthetic zooxanthellae and carotenoid pigments and makes for some of the most photogenic reef scenes at Pigeon Island.