The Oceanykan army ant refers to a family of species which are not so different visually as they are socially. Depending on the region, they might be from 5 to 23mm long. But the real difference is in how they act; some colonies have a complex military structure with officers, others manufacture and use dissolving acid, others craft small sharpened sticks, others glue small pieces of wood to their bodies for protection, others build advance posts as an early warning system, others practice slavery. Some live in scattered colonies of 10,000 or so individuals which unite in wartime, others live in massive centralised supercolonies with up to 150 million individuals.
Of course, humans normally don't take part in the affairs of ants, and just observe. Unless a kid with a flamethrower is bored.