Ant self-sacrifice

Minor worker of C. explodens with posterior body raised in a defensive pose. (Alexey Kopchinskiy)

New Delhi: Scientists exploring the forests of Borneo have discovered a new species of ants that explode to protect their colonies from predatory insects.

Although such exploding ants have been known to zoologists for over a century, a scientific paper published in the research journal Zookeys on Thursday describes a new species that scientists have named Colobopsis explodens.

The worker ants from this species display the strange defence behaviour that has intrigued scientists for long - they explode in response to threats from predators, their tiny explosions releasing a sticky toxic liquid to kill or slow down the enemy.

"It is voluntary self-sacrifice," said Alice Laciny, a zoologist at the Natural History Museum in Vienna, Austria, and a research team member. "Imagine a balloon filled with a sticky viscous liquid - the ants apply muscular pressure and they explode," she told The Telegraph over the phone.

Zoologists have long been intrigued by such exploding ants first documented in Southeast Asian forests in 1916. Scientists had until now classified the known species into a group collectively named Colobopsis cylindrica.

But Laciny and her colleagues from Austria, Thailand and Brunei travelled into the forests of Borneo for fresh studies of these insects. Over the past three years, they tracked the behaviour and activities of several species, including the new one they identified.

Their studies have revealed that while some workers explode, others use large plug-shaped heads to physically block the nest entrances from other predatory insects.

The capacity for exploding, Laciny said, appears to do with the social system of the ants. "The workers do not reproduce and have evolved a defence mechanism in which one or a few workers sacrifice themselves to protect the colony," she said.

The scientists say voluntary self-sacrifice is rare in nature, although observed earlier among termites and honeybees, in defence of their nests. But the behaviour of ants is different because they forage alone and explode during one-on-one confrontations, often far from their nests.


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