There’s nothing like drinking with friends, and it’s clear that ants can agree because they have their own version of what they drink.
But instead of drinking beer, the ants’ drink is a kind of nutrient-rich ‘milk’ that comes out of their young. All the colonists eat, from the very newborns to the adults.
These ants produce large quantities of this liquid at certain times of their growth. It looks like a storehouse of molten liquid, which includes the decaying material of the old cuticle of the pupa along with the nutrients that break it down. Hmmmm! Delicious!
Rockefeller University biologist Daniel Kronauer says: “In the first few days after hatching, larvae depend on water in the same way that a newborn baby depends on milk.
“Adults also drink less and, although it is not known exactly what it does in adults, we are confident that it affects metabolism and physiology.”
Lesson from @DanielKronauer‘s lab shows that a newly discovered “social fluid” appears to unite groups of ants in stages of development into a single organism. #RockefellerScience https://t.co/tnpL0QQZxe pic.twitter.com/77XHaqlzb6
– Rockefeller University (@RockefellerUniv) November 30, 2022
When they were first investigating how ants interact with each other, Rockefeller University researcher Orli Snir and her colleagues discovered this drinking ritual. After separating the young from the colony, the researchers manually removed the water from the other ants but left them alone.
The results were impressive.
“If we did not remove the liquid from the pupae that are isolated under favorable rearing conditions, they would drown in their secretions,” the researchers wrote in their paper.
Some pigs that were kept in boxes used in nests, instead of in a dry place, were infected with fungal diseases. But those who returned to the colony as soon as their “milk” came out had more life.
“This shows that, in a colony environment, the pupae depend on the adults to remove the female, and they would have died,” Snir and the team concluded.
Baby ants produce their milk during what appears to be hibernation – when they change from larvae to adults, as soon as they find their color. This is done to coincide with the hatching of the next batch of larvae.
Using blue paint, the team was able to show the new babies drinking the milk again.
The older caregivers carefully pick them up and place them on their older siblings to drink. If the newly born larvae did not receive this water in the first few days of life, they were likely to die.
The team also identified hormones and brain-stimulating substances in the pupa’s milk, along with amino acids, sugars, and vitamins.
While the original experiment was on clonal raider ants (Ooceraea biroi), Snir and his colleagues found that the same process occurred in one of the five major groups of ants.
“It probably existed once, early in the evolution of ants, or even before evolution,” explains Kronauer.
Individual ants interact with each other within their colony, often compared to working as a single organism – each colony has a specific function such as a single type of muscle or organ.
It is not clear how the pupa fluid affects the behavior of the ants, but researchers are eager to find out.
“The way ants use fluid creates a dependency between different stages of development,” says Kronauer. “It just shows how ants work as an integrated unit.”
This isn’t the first time alien ants have been caught eating, but it’s a surprising new discovery as the animal group has been studied intensively for over a century.
Their research was published in Nature.