I think it is actually a very interesting relationship. I am waiting for a flask of Myrmecophila which are named for their mutualistic relationship with ants that colonize the hollow pbulbs and fertilize them, and also protect them from other pests. I always thought the bullthorn acacias were cool so when I found out orchids enlisted ants as well I had to have some. Luckily they grow well without the ants. In the Acacias they live in hollow thorns, and are provided special packets of nutrients to raise their young, as well as nectar. They will seriously kick some butt if you mess around with the tree.