The incredible floating fire ant

Creepy-cool description of emergent behavior in ant colonies — complex survival strategies that develop when relatively dumb individual insects interact with each other in surprisingly complex ways.

Back in the lab, Mlot deposited colonies of 500 to 8,000 ants in large beakers. When gently swirled, each colony spontaneously formed a sphere.

Mlot dropped these spheres into water, and the amazing social behavior of ants became evident. The ants on top of the ball crawled down to the water and grabbed onto other water-level compatriots. The next layer of top ants then crawled to the edge, and so on. In about a minute and a half, each ant-sphere flattened into a dome, then flattened further into a pancake shape — a raft.

When the engineers flash-froze one ant raft with liquid nitrogen and scanned it under a microscope, they saw ants clinging to one another every which way — legs on legs, jaws on legs, jaws on jaws. They also counted about 21 / 2 layers of ants per raft.

This togetherness pushes each ant’s individual air bubble against the next ant’s bubble. The bubbles join, protecting the whole raft.

via The incredible floating fire ant – The Washington Post.