Last year, one species of ant was captured using antibiotics – now another has been observed in amputations.
Researchers have just confirmed through experiments that this surgery and other treatments that ants give each other actually save ants’ lives.
Although we’ve known for years that ants treat each other’s wounds, we’re just learning how amazingly complex and precise ant medical care can be.
“Ants are able to diagnose a wound, determine whether it is infected or sterile, and treat it accordingly over a long period of time with other individuals,” explains behavioral ecologist Erik Frank from the University of Würzburg in Germany.
“The only medical system that can compete with that would be the human one.
Frank and colleagues analyzed leg injuries in Florida carpenter ants (Camponotus floridanus). When tibial wounds were left unattended, only 15 percent of the ants survived.
But if nestmates were allowed to tend to the wounds, the survival rate of injured ants increased to a whopping 75 percent.
Wounds of the tibia were treated by mouth cleaning, in which the nurse ant held the delicate injured limb with its mandibles and front legs and licked the wound for a long time.
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But when carpenter ants encountered nestmates with an injury that matched our thighs, tiny surgeons first cleaned the wound before amputating the leg. This involved repeatedly biting the injured limb until it was severed.
Survival rates increased from 40 percent in ants with untreated femur injuries to about 90 percent after amputation.
Yet the ants never amputated legs with wounds near the tibia. So Frank and team experimentally amputated the ants’ limbs from the injured tibia to find that the ants’ survival did not increase.
“With the tibia injury, the flow of hemolymph was less impeded, meaning bacteria could enter the body more quickly. Whereas with the femur injury, the speed of blood circulation in the leg was slowed,” says Frank.
It takes the ants 40 minutes to complete the surgical amputation on the nest mate’s leg.
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“Unable to cut off the leg quickly enough to prevent the spread of harmful bacteria, ants try to reduce the likelihood of a fatal infection by spending more time cleaning the tibial wound,” explains evolutionary biologist Laurent Keller from the University of Lausanne. In Switzerland.
Infections are a major threat to animals, especially in social species where the risk of transmission is increased by being in close proximity.
Insects are known to mitigate some of these risks by destroying infected young or letting the nest die in isolation.
Medical care of nestmates is likely another such strategy, but how it occurred in ants is an interesting question, as there is little evidence that they can be learned. This suggests that such behavior may be innate, despite its complexity, as scientists hypothesize, but they want to experiment further to find out more.
“When you watch videos where an ant presents a wounded leg and has the other one willingly bite, and then presents the newly created wound for the next one to finish off.” [the] the cleaning process – this level of innate collaboration is quite astounding to me,” says Frank.
This research was published in Contemporary Biology.