Humans are no longer the only species on Earth that can perform life-saving surgery. A new study says that some species of ants can not only detect injuries in colony members, but also decide whether amputation surgery is needed to save that ant’s life.
Unlike humans, ants don’t have to go to medical school beforehand, and every ant in the colony is able to perform these seemingly basic medical interventions to ensure the survival of another ant.
Researchers from the University of Würzburg in Germany observed last year that a species of African ant, Megaponera analis, can treat infected wounds with antimicrobial substances they produce in their glands. For the new experiment, the same researchers chose a different species of ant: carpenter ants in Florida (Camponotus floridanus).
The researchers looked at two types of wounds located in different places on the ants’ legs: the femur and the tibia. They also infected the wounds with bacteria that would otherwise kill the ant that sustained the injury.
The scientists noticed that the ants could detect that one of their nestmates had suffered an injury and was potentially infected. Depending on the location of the wound, ants that detected the injury would then decide the appropriate course of action.
A wound to the femur would lead to amputation. On average, the ants spent approximately 40 minutes biting the injured fellow’s leg. However, if the injury occurred further down the tibia, the ants would choose to clean the wound rather than amputate the limb.
“When we’re talking about amputation behavior, this is literally the only case in which a sophisticated and systematic amputation of an individual by another member of its species occurs in the animal kingdom,” said study author Erik Frank. in a statement, for Live Science.
The researchers observed that amputation of a limb suffering from an infected femoral wound would significantly increase the patient’s chances of survival. The ants amputated 21 of the 24 injured ants from the femur and all 21 survived. The three who did not undergo surgery died. It is unclear why three of these Florida carpenters ads did not undergo the surgery.
In comparison, none of the 24 tibia-damaged ants had their limbs amputated. The researchers realized that the ants already knew that cutting off the leg of an infected nestmate with a tibial wound would not work.
Laboratory experiments showed that amputations for tibia-damaged ants had to occur immediately after the accident to reduce mortality.
While ants know how to perform the surgery, it still takes them 40 minutes to amputate a leg. By that time, the infection would have spread to the body of the infected nestmate and amputation would be pointless. This certainly mimics the approach people take when deciding whether a surgical intervention is worthwhile.
But why would thigh injuries benefit from amputation surgery in ants compared to tibia injuries? The researchers speculated that the muscles surrounding the femur have a larger surface area than those around the tibia.
When the muscles are injured, blood flow to the femur can slow down. Therefore, the bacteria may take longer to reach the rest of the body. Other ants have time to act and cut the entire leg.
A wound at the level of the tibia would not similarly affect blood circulation. Therefore, the bacteria would spread faster. The ants would have no chance to get rid of the damaged limb before it’s too late, so they use local wound treatment.
Experiments showed that topical treatment was able to reduce the bacterial load in ants injured by the tibia. However, pathogen load was significantly lower in femur-damaged ants with amputated limbs.
The results are incredible, showing the advanced behavior of ant societies when dealing with accidents and their subsequent infections. You can find the full study at Current Biologycomplete with videos showing ants treating an injured nestmate, including performing surgery.