In the event of a flood, some ants clamber on top of each other to make a living raft to protect the Queen and themselves. Even more remarkably, scientists have now discovered that each ant returns to the same spot in this make-shift lifeboat over and over again.
Scientists study self-assemblage – where insects build objects using themselves as the materials – to find why some ants can thrive in environments where others cannot. Past studies found Alpine silver ants survive in areas that are prone to flooding, by creating this type of living raft.
Researchers from the University of California, Riverside, simulated two floods in a lab and observed the position of each ant in the rafts. They colour-coded each ant to see if they remember the position they occupied in the previous raft.
Findings, published in the Science of Nature, showed the same ants consistently occupied either the top, middle, base or side of the raft. The researchers say this is the first time memory has been observed in ant self-assemblages.
"These elaborate rafts are some of the most visually stunning examples of cooperation in ants," said Jessica Purcell, a researcher working on the study. "Although people have observed self-assemblages in the past, it's exciting to make new strides in understanding how individuals coordinate to build these structures."