Why Are Giant Ants Letting Tiny Ants Crawl All Over Them?

Researchers in Arizona observed tiny cone ants cleaning much larger harvester ants, including inside their open mandibles.

The interaction appears to be the first documented case of one ant species grooming a much larger ant.

Scientists say the rare cross-species behavior could be a form of mutualism, where both ants may benefit.

The finding may help explain how cooperative behavior evolves in insects.