Dear Ant Blog,
All the photographs I see show ants using their mandibles like tongs. Can they rotate them like we can rotate our arms?
Despite the fact that ants use their mandibles for a multitude of different functions including prey capture, manipulation, and escape, there are no ants that have been proven to have fully rotational mandibles. Humans have a ball-and-socket joint that allows great range of motion, and although ants have a ball-and-socket joint for their antennae, their mandibles usually have a single plane of motion. Although this limits range of motion, it allows for much greater strength.
In case you are interested in reading more about mandibles, Chris Schmidt wrote a basic introduction to mandibular function as a part of the Tree of Life project. There are also several academic papers that detail the movements of mandibles (see Jurgen Paul), as well as some of the most extreme mechanical "trap-jaws" that have been convergently evolved by several ant species.
Hope this answers your question!
Max Winston & the AntAsk Team