Named after a carnivorous dinosaur, these fearsome, never-before-seen alive T. Rex ants are actually quite timid little critters, according to a new study. Before now, the biology and behavior of these ants were unknown.
Mark Wong, an entomologist and National Geographic Young Explorer, found the first live colony in northern Singapore. A dead ant of the genus, named Tyrannomyrmex rex, was first identified in Malaysia in 2003 by Fernando Fernández. Since then, others have been found in India, Sri Lanka, and Singapore – all deceased.
To make the challenge of finding T. Rex ants even more difficult, they are fond of moist, rotting wood buried in soil. The ants form nest chambers and cavities inside the decaying wood, where they work and breed.
Wong and co-author Gordon Yong found the ants due to military training activity in the region, which disturbed the forest floor and littered the area near the colony with food wrappings. Based on the nest they found, it’s possible the ants live in small, nocturnal colonies of about 30 individuals, although more finds are necessary to corroborate this.
The study, published in Asian Myrmecology, provides fresh details about these elusive critters. After initial observation, the researchers took the ants back to the lab, where they raised them in captivity for 10 days.
When the team nudged the ants or placed small invertebrates inside the container, their response was "timid" and "they curled their head and gaster inwards and under their legs and mesothorax, remaining motionless until the 'aggressor' moved on, after which the ants quickly moved away."
Only when a millipede crawled over multiple curled up workers did another worker ant sting the intruder. The largest of these workers came in at 4.52 millimeters – nothing to run away from – but a bit larger than the holotype discovered previously.
All this new information, however, brings with it new questions: Why do the ants lack metapleural glands, which produce a hygienic antibiotic fluid that protects them from bacteria and fungal growths inside their nests?
Another mystery is their timid, yet cannibalistic, behavior. The colony ate their only male – an odd behavior the researchers have yet to find an answer for.
"A single male T. rex emerged two days after the colony was collected," the authors write. "Unfortunately, the specimen was completely consumed by its nestmates soon after."
The ants did not, however, go for the drop of honey or the mites provided by the researchers. The team also didn’t find a queen ant, although that doesn’t rule out the possibility that Tyrannomyrmex rex colonies have one.
The trick that remains now is to discover more of these little insects to corroborate or adjust the team's findings.
[H/T: National Geographic]