The first ant colony formed around its queen, who came to settle in the ventilation pipe of an abandoned Soviet-era nuclear bunker in Poland. The wood ants built a large colony in this ventilation pipe, and the colony’s workers would often venture up to the surface world to gather food.
But the workers didn’t always make it safely through the pipe. Sometimes they would slip and fall down into the cold, dark and empty bunker below. Some of the ants would die from the impact. Others — perhaps as many as one million — would survive.
These fallen worker ants became a second “colony” living on the bunker floor, where they survived for years without light or a source of food — except for the steady stream of workers falling down the hole each day.
This lost “colony” of nearly one million wood ants persisted for years by preying upon their fallen brethren, according to a new paper published by insect researchers in Poland. The researchers found the ants in 2013 and announced their findings in 2016, but they’ve only now confirmed that the ants were eating each other.
“The corpses served as an inexhaustible source of food which substantially allowed survival of the ants,” the study authors wrote in their paper.
The findings are significant because social insects like ants don’t normally prey upon members of their own colony, the study authors say. Cannibalism usually only occurs when ant colonies are at war with one another.
The bunker was one of several nuclear weapons caches the Soviet Union established in western Poland. They’ve been empty and abandoned for decades.
Researchers led by Wojciech Czechowski, a professor at the Polish Academy of Sciences, did not find any other source of food in the bunker. However, they did notice that the fallen ants were building their own mound, much like they might have done on the surface.
In total, they discovered about two million dead ants and one million live ones in the bunker. There were no cocoons, larvae or queens to be found.
Researchers say these bunker ants show the “monumental potential” that wood ants have to self-organize, even under extreme circumstances.
Czechowski and his team installed a tiny boardwalk in the bunker so the fallen ants could finally reunite with their colony.
Nearly all of the fallen ants have returned to their original nest in the ventilation pipe, according to the study authors. They also did not observe any aggressive behaviour from the newly repatriated cannibal ants, who appeared to have left their corpse-eating ways behind.
In other words, the two ant colonies have become one again — and they all have access to the outside world.
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