Researchers from the University of Wurzburg have discovered that African Matabele ants will rescue their wounded after large raids on termite nests, a new study published in the journal Science Advances reports.
Each day, an ant scout will venture out to find foraging termites. When it does, it then rushes back to the nest and gets as many as 500 ants together for a raid. The mass then seeks out the termite mound and attacks.
Though this is typical behavior for the species, the scientists in the study noticed something strange would happen after these battles were over: the soldiers would help carry wounded ants back to the nest. This included insects that had lost a part of their body — such as a leg or an antenna — as well as ones that had simply been bitten during the fight.
To better understand this behavior, the team collected 20 random injured ants and made them return to their nest from a hunting site alone. Nearly 32 percent of injured ants died on the journey, with 57 percent of them succumbing to predators like jumping spiders because they could not move at a normal pace.
In contrast, only 10 percent of healthy ants were eaten by predators on the journey and not a single carried ant got attacked in 420 different raids. This shows that there is a clear benefit to the rescue operation.
“People always think that for ants or social insects, everything they do is for the good of the colony ” study leader Erik Frank, a doctoral student at the University of Würzburg, told Live Science. “Here we show, for the first time, an example where the good of the individual, of saving an individual ant, is good for the colony as well.”
In addition, wounded ants returned to battle roughly 95 percent of the time. It only took the hurt soldiers one day to get used to their new injuries before they could move again at close to normal speed.
This behavior is surprising to scientists because social insects like ants typically do not value the individual as much as the colony. The team believes the reason this behavior evolved is because the population depends on the wounded to sustain their numbers. Each ant that is saved is a member of the nest. Researchers estimate that without those survivors the colonies would be almost a third smaller than they are.
“We have observed helping behavior vis-à-vis injured animals for the first time in invertebrates,” said Frank, in a statement.