Sea Fan (Gorgonian)

Photo: Luis P. B. · CC BY-NC

Enormous sea fans up to 2 meters across dominate Planet Rock's deeper walls, oriented perpendicular to the prevailing current to maximize their filtration of passing zooplankton through their polyp-studded branches. These long-lived organisms — some individuals exceeding 100 years — create complex three-dimensional habitat that supports dozens of commensal species including pygmy seahorses, longnose hawkfish, and clingfish that spend their entire lives on a single fan.