Black Coral

Black coral trees colonise the deeper sections of the Ilhéu de Ferro pinnacle below 20 metres, their dark branching skeletons draped in polyp tissue that ranges from white to greenish-gold depending on the light angle and the density of zooplankton in the water column. Despite their name, living black corals display a range of colours and only the bare skeleton is black — a feature of the protein-based antipathin that forms their structural core, which has made them targets of historical harvesting for jewellery across the Atlantic islands. Their presence on this pinnacle is ecologically significant as habitat-forming deep reef engineers that provide shelter for small fish, brittlestars, and commensal shrimp species, and their slow growth rates of less than 2 centimetres per year mean that the large colonies visible here represent decades of undisturbed growth.