Species: Southern Cassowary (Casuarius casuarius) Role: Spreads large rainforest seeds no other species can, enabling forest regeneration.
A keystone species is an organism that holds a critical role in maintaining the structure, balance, and health of its ecosystem. Like the keystone in an arch, its presence supports entire ecological communities — from prey and predators to plants and processes. Without it, the ecosystem could dramatically change or collapse. These species may not always be the largest or most visible, but their impact is profound and irreplaceable.