It Turns Out That Ants Can Amputate, Too

Just like humans, ants benefit from living in a group. Studies have shown some ants carry wounded colony members back from battle and lick their wounds, for a 90% survival rate. Now, new research indicates carpenter ants go a step further, carrying out life-saving amputations on their wounded brethren. It's the "first example of a non-human animal severing limbs to curb infections," per the Guardian. "I did not believe it," Dr Erik Frank, an expert in behavioral ecology at Switzerland's University of Lausanne and lead author of the new study, tells CNN. "The ants are able to diagnose, to some extent, the wounds and treat them accordingly to maximize the survival of the injured," he adds, per the Guardian.

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Researchers cut various Florida carpenter ants (Camponotus floridanus) on an upper or lower limb, then watched how nest mates responded. Thirteen of 17 ants cut on a thigh underwent amputation and more than 90% survived, compared to less than 40% for those who went untreated in isolation. "Nest mates would begin licking the wound," then move to the joint with the hip bone, where they "proceeded to repeatedly bite the injured leg until it was cut off," according to the study published Tuesday in Current Biology. Interestingly, none of nine ants cut on the lower leg underwent amputation. Nest mates only licked the wound, likely removing bacteria, resulting in a 75% survival rate, per CNN.

In another set of experiments, researchers found amputations helped those ants with infected upper limbs, but not those with infected lower limbs. As the Guardian explains, thigh wounds "were associated with damage to structures that pumped a blood-like substance around the ants' bodies," which slowed the spread of infection. Infections in lower leg wounds, in contrast, spread rapidly around the body, making a 40-minute amputation futile. Basically, ants are making treatment decisions based on the location of an injury, researchers say, adding it's all about maintaining the size and strength of a colony. Frank tells the Guardian roughly 10% of Florida carpenter ants that go out in search of food "carry an injury from a previous day." (More discoveries stories.)