For the first time, an extremely rare ant has been seen alive.
Tyrannomyrmex rex (T. rex for short) had eluded scientists since 2003, when entomologist Fernando Fernández revealed that a single dead ant from Malaysia represented a never-before-seen ant genus. The ant’s tiny mandibles reminded Fernández of the stubby arms of Tyrannosaurus rex and other carnivorous dinosaurs.
In the years since, only a handful of Tyrannomyrmex ants have been found in India, Singapore, Sri Lanka, and probably the Philippines, all of them deceased and incidentally collected from leaf litter.
But after digging in the dirt in a Singapore forest, National Geographic Young Explorer and entomologist Mark Wong has found the first recorded live colony of T. rex ants—revealing crucial details about the species, as well as additional mysteries. (Watch a recently discovered ant behavior: “warring” ants carrying their wounded off the battlefield.)
“The best way to collect and observe live ground ant colonies is to really get your hands dirty, by gradually excavating the soil from an area, layer by layer—sort of like an archaeologist,” Wong says in an email.
Tracking Down T. rex
It may seem strange that an ant colony is hard to find, but ants in the genus Tyrannomyrmex don’t exactly advertise themselves. Not only do the insects live in small colonies of about 30 individuals, they’re also likely nocturnal and appear to be very picky eaters, making baited traps next to useless.
In addition, Wong says that the ants appear to live in an understudied habitat: pieces of moist, rotting wood submerged in soil.
In their description of the live colony, published recently in the journal Asian Myrmecology, Wong and Yong note that recent military exercises had freshly disturbed the forest. Understory plants had been trampled, and food wrappings littered the ground.
Amid the mess, they found a piece of rotting wood whose two hollow cavities housed the colony. From there, it took painstaking work in the dirt to get the colony into a “nest tube,” a glass test tube half-filled with water.
A Timid ‘Tyrant’
Once back in the lab, these ants with a fearsome name proved quite timid.
In petri-dish “cafeteria experiments” aimed at determining the ants’ diet, Wong and Yong found the ants often froze up and ran away when other organisms came close.
“I had a good laugh when I saw them respond in this manner to little millipedes, mites, smaller ants, and basically whatever prey I tried to offer them,” says Wong. “They wouldn’t even get close to honey—and only gently prodded [a] honey droplet with their antennae.”
After fleeing from other bugs and rejecting honey, the team was at a loss as to what the animals eat, though it’s possible the ants eat tiny invertebrates or insect eggs.
In addition, T. rex has a fairly robust stinger it’s not afraid to use. At one point during Wong and Yong’s observations, “an unfortunate millipede” ambled near the colony’s eggs and larvae, quickly receiving a sting from a protective worker ant.
‘Scraping’ for Answers
Despite the discovery, questions linger. Tyrannomyrmex ants, for instance, bizarrely lack working metapleural glands, organs that secrete antiseptic compounds crucial to ants’ personal hygiene, a vital concern within a colony’s close quarters.
“What’s truly puzzling is that Tyrannomyrmex species live within a presumably pathogen-rich environment (i.e., the soil and decomposing matter),” says Wong. “Tyrannomyrmex hygiene remains a little mystery.”
Other aspects of the colony’s behavior were also puzzling. The colony cannibalized its lone male, an unusual behavior, says Gary Alpert, a research associate at the Museum of Northern Arizona and Harvard University. In addition, Wong and Yong didn’t find a queen among the ants they collected. (Read “This Is Why Insects Rule the World.”)
“This is a major contribution in understanding colony structure of Tyrannomyrmex,” says Alpert, who wasn’t involved with the new observations.
Further insight will help uncover more about these tiny tyrants, but getting them will be tricky. Wong and Yong haven’t yet found another colony, despite returning to the same area. But Wong remains undeterred.
“It’s a pretty exciting time to be an ant scientist who enjoys ‘scraping it out’ in the dirt,” he says.