- A symbiotic relationship is one in which two or more species interact with one another in partnership. Sometimes taken to refer exclusively to mutually beneficial engagement, symbiosis is a broader category of interspecies interactions that can also include relationships harmful to one of the species. Mutualism is the technical name for the ant-acacia relationship.
- Some species of acacias rely on ants to actively defend them against herbivores. The partnering types of ants find habitat in acacia thorns and sustenance from the tree's nectar and corpuscles. Many other acacias contain various chemicals that ward off herbivory, and thus have no need for ant protection.
- Mutualistic relationships between certain species of ants and acacias exist in Africa and the Americas. One of the most well-known systems is that of the swollen-thorn acacias and associated ant species of the Neotropics, as researcher Daniel Janzen described in the 1960s.