The exploding ants of Borneo were first described by Ulrich Maschwitz in 1974. These ants in the genus, Camponotus, would respond to even a light touch with forceps by “exploding”. The body wall would rupture and a sticky yellow “goo” ooze from the ant and glue it to the forceps. These ants are territorial and defend their arboreal nests from invader ant species. When exposed to European ants in the laboratory, the exploding Camponotus ants would grasp the invader by the leg or antenna, press its body to the head of the invader and squeeze its abdomen until the abdomen ruptured spilling glue over the eyes and mouthparts of the invader ant. The ant duo, locked in a death grip, tumble to the forest floor to be consumed by other predators.
Recent investigation by a group of scientists* determined that the mandibular gland, commonly used for digestive enzymes in most ant species, is greatly expanded in the exploding ants. The glands are abnormally large, even extending into the abdomen and filling a substantial portion of the space.
Other than their size and function, the glands in the exploding ants are not unusual. Often in evolution, a structure initially used for one purpose is used for another purpose and undergoes modification. In this case, the mandibular gland was initially used for digestion. Once ants started using the secretions for defense, the glands enlarged to their present size. The ability to “explode” or have the secretion ooze from the ants at multiple locations is more effective at gluing the ants to the invaders.
Grabbing onto a larger invader and “exploding” like a suicide bomber is an effective defense and allows one smaller defender to take out a larger invader. Apparently, ants have been conducting asymmetric warfare much longer than humans.
*(Histology of structures used in territorial combat by Borneo’s ‘exploding ants’. Diane W. Davidson, Kamariah A. Salim, & Johan Billen. Article first published online: 24 AUG 2011
DOI: 10.1111/j.1463-6395.2011.00523. —Acta Zoologica (Stockholm) 00:1–5.)