As tiny critters surrounded by big threats, ants have evolved a number of unique ways to protect themselves: they bite, they sting, they fling themselves to safety. But amid the treetops of Borneo, one species of ant resorts to a particularly dramatic method of warding off predators: it tears its body apart to release a toxic secretion, killing itself in the process.
According to Allyson Chiu of the Washington Post, a team of researcher has described the species, which they aptly dubbed Colobopsis explodens, for the first time in the journal ZooKeys. The body of C. explodens is filled with glandular sacs containing a toxic, yellow secretion. If an enemy proves too persistent, these little insects will angle their backsides close to the predator and contract their muscles so tightly that their skin bursts open and release the goo, which has a “spice-like, curry-like” scent, Alice Laciny, a doctoral student at the Natural History Museum in Vienna and lead author of the study, tells Chiu.
Not all C. explodens possess this trait. Only the minor workers are able to rupture their body wall. It is the ultimate act of self-sacrifice; they give up their lives in order to keep threats away from the nest.
“Imagine a single ant is like a cell in a human body,” Laciny tells Chiu. “The exploding workers work as immune cells. They sacrifice their lives to hold off danger.”
C. explodens belongs to the species group Colobopsis cylindrica, which encompases the wide umbrella of exploding ant species. Self-destructive tendencies among some ants were first observed in 1916, but the new report marks the first time since 1935 that a new species has been described, according to a summary by the publishers of the journal.
Because these strange and remarkable creatures have not been well studied, an interdisciplinary team from Austria, Thailand and Brunei came together in 2014 to classify different species of exploding ants. Researchers have identified at least 15 distinct species, "most of which," they write in the paper, "are probably new to science." C. explodens is the first one they have formally described. Previously, C. explodens was simply known as “Yellow Goo,” after the color of its toxic secretion.
As Hannah Ellis-Peterson points out in the Guardian, the ants’ suicidal altruism, formally known as autothysis, is not unheard of among insect species that live in large colonies and work closely together to ensure the success of group. Certain termites, for instance, can rupture their bodies to release a substance that blocks off access to the tunnels where they live. But in the new report, the study authors note that even among exploding ants, C. explodens is “extremely prone to self-sacrifice when threatened.”
Moving forward, Laciny tells Jason Bittel of National Geographic, the research team hopes to learn more about how C. explodens workers coordinate attacks on large predators—and discover what is inside their deadly—though aromatic—yellow goo.