Groups Move Efficiently

group of reddish-brown ants on tan gravel

Biological Strategy

Burchell's army ant

AskNature Team

Image: Axel Rouvin / Flickr / CC BY - Creative Commons Attribution alone

Coordinate by Self-Organization

To create and maintain a healthy community of individuals and ecosystems requires that living systems coordinate their activities. Coordination doesn’t necessarily mean that there’s a leader orchestrating what happens. In nature, coordination is usually achieved through self-organization. In a flock of geese flying in a V-formation, for example, there’s no lead goose controlling where all of the others fly. The flock uses this formation because each goose gains energy from air vortices created by the goose in front of it. The lead goose doesn’t gain that benefit, so when it tires, it moves back and another goose takes the front position.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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Army ants move efficiently in large numbers by maintaining three lanes of traffic; two outer lanes travel opposite the inner lane and are governed by behavioral differences related to possession of food.

“By forming three lanes of traffic during hunting expeditions, army ants in Panama come close to achieving the maximum possible rate of traffic flow. Given that army ants are blind, and that a hunting party might consist of 200,000 ants marching in opposite directions, it is surprising that they are able to maintain such efficiency. The answer lies in the behavioral differences between ants with food and ants without. Ants returning from a successful hunt are less likely to deviate when bumped. Weighed down by their prize, they simply continue to march in a line, guided by the pheromone trail of the ants in front of them. Ants traveling away from the nest carry no food, and are more likely to get out of the way. The result is a middle lane of food-toting ants moving in one direction, and two outer lanes of unburdened ants moving in the opposite direction. Using a computer model, researchers from Princeton University and the University of Bristol learned that, as behavioral differences decrease, traffic efficiency goes down. If burdened and unburdened ants behaved in roughly the same way, the three-lane system would deteriorate.” (Courtesy of the Biomimicry Guild)

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