Fire ants’ survival trick of forming rafts in floods

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In tropical areas hit by the floods, it's common to spot small brown debris-like “blankets” floating on the water. If you accidentally poke them or push it underwater, you will find that these “blankets” are alive and their composing elements – “fire ants,” would immediately climb onto you and with its sting, giving you the feeling of being burned.

The small brown debris-like “blanket” is formed by thousands of fire ants. /VCG photo

The fire ant Solenopsis invicta, is commonly seen in the areas of the southern United States, especially during floods. Among many areas hit by Hurricane Florence, swarms of them are seen forming “the Noah's Ark,” floating on flood water.

The fire ants in a test tube. /‍VCG photo

The fire ant has evolved the capacity to form survival rafts in that it originally lives in the rainforests of Brazil where floods frequently take place. They can drift for weeks until they find the dry land needed to rebuild their anthills.

Fire ants caught by epidemic prevention personnel in South Korea. /VCG photo

According to Texas A&M University, these rafts contain all members of the ant colony – the queens, the workers, the eggs, and the larvae. Each raft is made up of thousands of fire ants and it can be constructed in approximately 100 seconds. The construction process is similar to the weaving of a fabric.

The self-assemble raft made by fire ants. /VCG photo

In addition, their cooperation on water is very effective and each performs its job well. Fire ants on the bottom can stay in their posts for weeks without changing shifts with fire ants on the top. Once they reach solid surfaces, they “unconsciously” flee in all directions and the rafts disintegrate.

Apart from the water-repellent rafts that fire ants form, they can also quickly link their bodies to construct ladders, chains and walls, according to research by Georgia Institute of Technology. Although its brains have less than one ten-thousandth as many neurons as a human's, its effectiveness in complex teamwork is marvelous.