Florida Carpenter Ants Perform Life-Saving "Surgeries" On Wounded Nestmates

Ants are known for their teamwork. The tiny insects work together to build homes, find food, and care for their young. Now, a new study has found that Florida carpenter ants even perform life-saving "surgeries" to save their nestmates. This remarkable social behavior has never been observed in a non-human species before.

Florida carpenter ants are native to the southern United States. The reddish brown insects live inside rotting wood and often sustain injuries while defending their homes from rivals. But unlike some other ant species, Florida carpenter ants lack the special glands that produce antimicrobial substances to treat infected nestmates.

Curious to know how these ants responded to battle-related injuries, Dr. Erik Frank and his team at the University of Würzburg, brought back some specimens to their lab in Germany.

The researchers began by injuring the legs of around 100 ants. Some ants suffered cuts on their femur, or upper leg, while others were hurt on their tibia, or lower leg. The wounds were then exposed to a commonly found soil germ.

The injured ants were divided into two groups. Some were left to fend for themselves, while others were placed back in their nests. The injured ants in the nest received immediate attention from their mates. The ant "doctors" began by cleaning each wound with their tiny mouths. Their next step depended on the type of injury.

For those with femur injuries, the ants would carefully bite off the leg, completely removing it. Each amputation took at least 40 minutes and involved multiple "surgeons." This extreme measure helped stop infections, resulting in a 90 percent survival rate among the treated ants. In contrast, only 40 percent of the isolated ants with femur injuries lived.

Tibia wounds were treated with a mere lick to remove the bacteria. This simple action helped save 75 percent of the injured ants. By comparison, only 10 percent of the isolated ants with tibia injuries survived.

The scientists believe the treatment decision is linked to the flow of hemolymph, a fluid similar to blood in invertebrates. A high-resolution image of the ant's leg revealed that the femur has more muscle tissue than the tibia. The muscles help slow down the "blood" flow, preventing bacteria from spreading quickly. This gives ants the time needed to perform the amputation.

An ant's tibia, on the other hand, has less muscle tissue to stop the "blood" flow. This allows infections to spread much faster. Since amputations would take too long, the ants focus on cleaning the wound instead.

"The ants are able to diagnose a wound, see if it's infected or sterile, and treat it accordingly over long periods of time by other individuals — the only medical system that can rival that would be the human one," said study leader Dr. Erik Frank.

The scientists published their findings in the journal Current Biology on July 2, 2024. They next plan to explore whether other ant species perform similar "surgeries" to save their friends.

Resources: Sciencealert.com, Livescience.com, Science.org