Adventures Among Ants - Mark W. Moffett [47]
While participating in a lift-and-carry operation, each of the marauder ant “porters” performs a slightly different task. As when several people haul a piano, an ant’s movements depend on where she is located relative to the direction of motion. Workers at the forward margin walk backward, pulling the burden. Those on the trailing edge walk forward, apparently pushing it. Ants along the sides shuffle their legs sideways and slant their bodies in the direction of travel. The ants sort out their roles during a few minutes of turmoil, then whisk the item off with effortless grace. When a media worker joins in at the front or back ends of large booty, she appears to be adept at guiding the group around obstructions or through shifts in the trail course, performing another valuable role in the transport team.
BUT IS IT TEAMWORK?
Should we consider these groups teams? Dictionaries define the word team as a group organized to work together, which could apply to many social situations among ants. Although in many team sports there is a set roster for each game, with ants, under most circumstances, the participants change and are interchangeable.11 We saw this for raids: marauder ants come and go while the quarry is being subdued, and similarly to and from the raid as a whole. By comparison, transport groups are more stable, though ants may leave or join a group when, for example, an object becomes snagged, at which point the participants must sort out their movements relative to each other afresh.
Often, members of human teams divide the labor, doing different things at once to get the job done. Although ant workers cannot recognize each other as individuals in the way human teammates do, many marauder ant activities—among them killing prey, attacking alien ants, and maintaining trails—probably conform to the American football model.12 In some cases, different worker castes play specific “positions” and concentrate on distinct tasks, as when minors hold down prey while medias and majors shear its limbs. In other situations, all participants belong to the same worker caste and show flexibility in how they do their jobs, as when minor workers perform differently in the transport group depending on where they are located around the prey.
One species of wood ant shows the ultimate division of labor in a transport team, with a degree of leadership exceptional among ants. Among Formica incerta, common in New England fields, when a successful forager can’t move an item of food herself, she attracts ants in the vicinity or recruits some from the nest. Unable to assess the size of her find, she may not gather a suitable number of individuals. If not enough helpers arrive and she needs to leave to find more, those already on scene—even if they have already started carrying off her find—will wander away as if the food weren’t there. Only the original food finder can keep the team motivated, and only she can go for more help. She must be present to guide the transport team from start to finish. Outside her role with this particular meal, of course, there is nothing special about her. If she is later recruited by another scout, she goes to work as a regular worker, while the individual who located the food becomes the supervisor for its retrieval.13
Several years ago in El Salvador I watched workers of the army ant Eciton burchellii chop a scorpion to pieces. I could see that the workers fell into different positions as the