Some species or species groups may be more important than others in helping the Great Barrier Reef function and continue to provide its ecosystem services. Identifying these species is a crucial component of maintaining the highly biodiverse Great Barrier Reef into the future. Prof. Peter Mumby from the University of Queensland leads NESP Tropical Water Quality Hub Project 4.6, which aims to identify and rank the Great Barrier Reef’s ‘keystone species’ and has now published a final report, available on the Tropical Water Quality Hub website. The report identifies a range species groups as (1) vital to the survival of the reef, (2) vulnerable to its ongoing health pressures, and most importantly (3) both vital and vulnerable. Some of these were expected, such as branching corals (Acropora genus), microorganisms and herbivorous parrotfishes. Others, such as cleaner wrasse, bivalves, coral-associated crabs and detritus-feeding fishes, were interesting ‘surprises’, giving decision-makers new objectives to work toward. The report ultimately recommends local action to prevent degradation of reef structures and associated losses of ecosystem functions and services, in addition to fast action on climate change.