Fire ants make ‘floating island’

When waters start to flood a fire ant colony, they take evasive action.

Fire ants in a group often act like a pourable fluid.

A photojournalist for WHNS-TV spotted what appeared to be mud floating in Greenville County flood waters Sunday, but he soon discovered the clump was actually an “island of ants”. “In under two minutes, fire ants can link together to assemble floating rafts, Davis told USA Today Network”. But how they stay afloat has puzzled biologists for years.

A pile of 500 ants floats on water in a laboratory.

To better understand how the raft works, a team of scientists from the Georgia Institute of Technology in Atlanta used time-lapse photography to scrutinize the dynamics of the raft.

Fire ants can survive in a raft up to several weeks, though they must eventually reach dry land if they are to restart their colony. They studied the phenomenon. A video online shows the ants forming a life raft out of their own bodies. However, if other liquids – soap, for instance – were to mix with the water, the surface tension would be lowered and the ants would drown. This grip is twice as strong as the force it needs to stick to glass.

A lone ant steps onto the water in a lab.

Researchers first observed this unique survival strategy when studying fire ant populations in 2011. In water emergencies, they can strap the queen and larvae onto the top of the raft to preserve the precious cargo.