In a previous post I mentioned how scientists studied ant navigation using the sun and memories. In relation to that story, here is a video that shows an ant on a treadmill having it's behavior studied.
A beetle has been found to hitch rides on the butts of army ants. The beetle has adapted itself to look like the abdomen of an army ant. So far it's unknown as to how the beetle fools the ant into not realising it's there. https://www.newscientist.com/article/2120872-new-beetle-species-bites-army-ants-butt-and-hitches-a-ride/