Playing dead is a common defense mechanism in the animal kingdom, but scientists in Australia have discovered an example on a whole new scale. Entire colonies of ants were found to be feigning death, in a collective behavior that’s never been recorded before.
Predators usually aren’t interested in eating prey that’s already dead, and a wide range of animals use this to their advantage. The North American opossum is so famous for faking it that it spawned the phrase “playing possum,” and the behavior is seen in many mammals, birds, reptiles and insects.
That list includes some species of ants, but usually only individual insects do it in the face of danger. Scientists have now discovered a whole colony of Polyrhachis femorata ants getting in on the act.
Researchers at the University of South Australia (UniSA) were investigating nesting boxes for wild animals on Kangaroo Island, when they came across a box full of dead ants. They didn’t think much of it, until one amateur flubbed its lines and moved, ruining the performance for all of them. Over the course of the project, the team repeatedly saw the same melodramatic scene.
“The mimicry was perfect,” said Associate Professor S. “Topa” Petit says. “This sort of defensive immobility is known among only a few ant species – in individuals or specific casts – but we don’t know of other instances when it’s been observed for entire colonies. In some of the boxes containing colonies of Polyrhachis femorata, some individuals took a while to stop moving, and others didn’t stop. The triggers for the behavior are difficult to understand.”
The team expects that this group death-feigning behavior, known as thanatosis, will be found in other ant species, and will help researchers learn more about this little-studied insect.
The research was published in the Australian Journal of Zoology.
Source: University of South Australia