Adventures Among Ants - Mark W. Moffett [116]
A colony this big is comparable in many ways to a cow or a deer. The ant population weighs 15 to 20 kilograms, as much as a newborn calf—or an adult red brocket, a Latin American deer that lives in the same forests as many leafcutters. Leafcutter nests consume as much vegetable matter in a year as does one red brocket: up to 280 kilograms, enough leaves to blanket a soccer field.20 As we shall see, the assemblage of ants in a colony processes forage in much the same way as a cow does, from chewing the raw material to excreting the remnants. The gardens are the equivalent of the cow’s rumen—but whereas the rumen makes use of a slurry of bacteria, protozoa, and fungi to extract the proteins and fatty acids a cow needs, a garden requires only one fungus species to process foliage into a complete ant chow.21 Both ant and cow find and prepare plant matter for their microbes, which they house under ideal conditions; the ants will relocate gardens if the temperature or humidity falls outside a suitable range.22 Just as algae and fungi have combined to form an organism known as a lichen, and the gut flora have become an essential part of a cow or a deer, the garden fungus has been integrated into the leafcutter superorganism.
INDUSTRIAL FARMING AND TRANSPORT
Farming requires a diverse skill set in ants, as it does in humans. Today, humans farming on a large scale use tools and machinery to handle different steps in the process, but in ants, different skills reside in different workers, and as we have seen, polymorphism plays an important role in this. The biggest leafcutter colonies are extraordinarily polymorphic, with the largest soldier having two hundred times the mass of a small worker.23
Ant colonies have been likened to a factory in a fortress.24 I find the metaphor particularly apt for leafcutters. Their multiple-step procedure, in which all get involved, dwarfs the two-step process by which a marauder-ant media worker extracts a seed from a grass stalk and a minor carries it away. The leafcutter workforce is self-directed, adjusting to the local requirements of colony and fungi without the oversight of any foremen. In business terms, it has the flat organizational structure adopted by corporations from Hewlett-Packard to IKEA, with the absence of middle management enhancing cost effectiveness and the organization’s responsiveness to rapid shifts in needs.25 Most leafcutter activities are accomplished with little communication: as is done in any well-run assembly line, the gardeners simply do the task that comes before them.
A leafcutter factory might have been the envy of Henry Ford: different workers collect, transport, and mince foliage, apply it to a garden, and eject its decayed remnants in an orchestrated flow of material from environment to nest and back out again. Many steps are managed by ants in a narrow range of sizes.26 Mid-sized workers cut the foliage, carry it into the nest, and drop it onto the garden surface, where, as the production line unfolds, ever smaller ants accomplish more delicate tasks. Workers with heads about 1.6 millimeters wide shred the greens into scraps. Slightly smaller ants further masticate the chunks, now discolored from abuse, into a moist pulp. Still smaller ants, using their forelegs, implant the pulp into the garden. Tiny ants with heads a millimeter wide lick the pulp and seed it with tufts of fungus from established