Giant Sea Fan

Photo: Luis P. B. · CC BY-NC

Sea fans grow to enormous dimensions on the João Vieira wall, with some colonies exceeding 2 metres across, spreading their feeding polyps into the current that flows along the drop-off edge. They are suspension feeders that capture plankton and organic particles, and their branched structure provides habitat and shelter for dozens of associated species including pygmy seahorses, longnose hawkfish, and basket stars. The slow growth rate of large gorgonians — some of which may be decades old — makes the intact wall ecosystem here particularly irreplaceable.