Fire Ants…in Water

In the aftermath of Hurricane Harvey, we are all worried about the residents of Houston and the Galveston Gulf Coast. Hurricanes and flooding are a deadly serious matter and my heart goes out to everyone dealing with loss or damage caused by the disaster. As Houston residents and first responders worked together to survive and mitigate the floodwaters with boats, pumps, sandbags, and evacuations, they were treated to the (horrible) spectacle of a very different group of social animals responding to the crisis with a different group strategy.

Red fire ants (Solenopsis invicta) are a tough species of stinging fire ants from South America. Like humankind they are invasive generalists which can survive anything and have quickly spread worldwide because of their hardy resilience and various ingenious group strategies. I have been meaning to blog about them because they are a sort of alien red mirror of humanity (and I have been trying to get back to writing about superorganisms and the question of what constitutes an organism anyway). Because of the hurricane, the fire ants have injected themselves into the news cycle, so I am going to mention their flood strategy now and we can return to write about their other interesting behaviors.
Fire ant bodies are waxy and light. They float! But they would all be drowned or swept apart in a serious flooding event (and a single ant separated from the group is effectively dead). Thus when the fire ants sense rising waters they group together in a ball and tightly cling to each other. These living rafts of clamped together ants can float for many days.

If you are in a flooded area and a ball of furious stinging ants floats by you, entomologists and fire ant experts recommend that you not molest it. Like Voltron, the ants can break apart into autonomous fighting units before reforming. Ants do not breathe like people and they drown sort of gradually. We will leave the ants alone and concentrate on human group strategies for getting through crises.

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