Indian jumping ants, or Harpegnathos saltator, are unique in more ways than one
A decreased brain size is thought to allow the ants to divert their energy to egg production, as brain tissue is metabolically expensive to maintain, the study says
Indian jumping ants can shrink their brains by 20 percent and then expand them back again to allow energy to be temporarily diverted towards egg production, according to a new study.
The inch-long arthropods were already known to be able to catch and kill prey twice their size, jump four inches in the air and compete in 40-day royal rumble deathmatches to decide the next queen of the colony. Now new research shows that females prepare their bodies to lay eggs by releasing hormones that make their brains shrink by around 20 percent and cause their ovaries to balloon to five times their normal size. A decreased brain size is thought to allow the ants to divert their energy to egg production, as brain tissue is metabolically expensive to maintain, according to the study, which was published in the journal ‘Proceedings of the Royal Society B’. Other insects, including honeybees, are known to be able to shrink their brains, but the Indian jumping ants, or Harpegnathos saltator, are the only ones known to be able to grow them back.
“If you look inside their bodies, you can see the huge transformations that they undergo,” said Clint Penick, assistant professor of biology at Kennesaw State University in Georgia and lead author of the new study.
The changes start shortly after the death of the colony’s queen ant-typically the only one allowed to lay eggs.
Unlike other insect colonies, there is then a physical fight between hundreds, sometimes thousands of females to become the next queen, with competitors beating each other with their antennae.
The dust-up lasts up to 40 days until a handful of victors emerges, but by then, all of the females have already started an internal transformation spurred on by hormones.
Only the victors will go on to lay eggs, so researchers examined what happened to the females which didn’t.
“I thought they would probably just die, but within a couple of days they completely switched back,” Dr. Penick said. “It was pretty amazing to see that they were able to completely re-expand their brains to the exact same size that they were before.”
The re-calibrated females went on to continue in their roles as workers, maintaining the colony.