Melissotarsus is quite possibly the strangest ant I’ve ever encountered. It lives only in narrow galleries in the bark of particular species of African trees. It might be the only animal besides humans to farm other species for meat. The adults spin silk.
And Melissotarsus is so adapted to crawling about tight passages in tree bark that, outside the confines of the nest, workers are often incapable of standing upright. When I put the individual above on a piece of white plastic, she promptly fell over and could not right herself.