Cooperative transport in ants (Hymenoptera: Formicidae) and elsewhere

Czaczkes, T.J.; Ratnieks, F.L.W.

Abstract: Cooperative transport, defined as multiple individuals simultaneously moving an object, has arisen many times in ants, but is otherwise extremely rare in animals. Here we review the surprisingly sparse literature available on cooperative transport. Cooperative transport abilities in ants are a continuum, but three general syndromes are described: uncoordinated transport, in which transport is slow, poorly coordinated and characterised by frequent and long deadlocks; encircling coordinated transport, in which transport is fast, well coordinated, and with few deadlocks; and forward-facing coordinated transport, carried out exclusively by army ants, in which one worker, usually of larger size, straddles an item at the front while one or more smaller workers help to lift at the back. In the two coordinated syndromes, the groups of ants involved constitute teams, and specialised recruitment to large items and adjustment of carrier number to match item size may occur. Some features of cooperative transport are specific adaptations, whilst others are already present in the behaviour of ants carrying items alone. One major benefit of cooperative transport appears to be that it allows a colony to utilize large food items in an environment with aggressive or dominant competitors by quickly removing the item to the nest rather than having to cut it up or consume it on the spot. In addition, compared to individual transport, cooperative transport may have other benefits such as increased transport speed or efficiency. The study of cooperative transport also includes computer simulations and robots. These provide biologists with new perspectives and also formalise questions for further study. Likewise, lessons learned from cooperative transport in ants can inform computer scientists and roboticists.

Myrmecol. News 18: 1-11; printable