Ants Use Babies for Life Raft When It Floods

While trying to survive a flood, ants make themselves into a life raft formed with their own bodies and place their babies at the bottom of the "boat," a new study found.

Published in a PLOS One report, the findings show that these "ant-rafts" play to the strengths of each type of ant and raise the group's chance of survival, the Los Angeles Times reported.

Surprisingly, the younger and more vulnerable members of the colony are placed on the very bottom of the life raft, where they are exposed to fish and at greater risk of drowning.

"It was an interesting contribution. No one had really looked at this idea of the brood as a flotation device," said David Hu, a mechanical engineer at the Georgia Institute of Technology who was not involved in the study, as quoted by the L.A. Times. "It adds a level of sophistication to the rafts that was previously not understood."

Ant colonies can work together in astonishing and formidable ways, building bridges with their bodies, surrounding intruders to kill them through body heat and making these life rafts out of their own bodies.

The team at the University of Lausanne in Switzerland researched an ant colony's habits by collecting some ant workers, a queen, and a few brood ants, or ants still in larval and pupal form, and then putting them in flood-type conditions.

In the lab, the ants were placed into groups of 60 workers with a queen and some brood ants. When the researchers gradually began raising the water levels, the ants reacted by forming a life raft, where the valuable queen was placed in the middle.

While the placement of the vulnerable young on the bottom of the ant-raft seems counterintuitive, the scientists discovered that the larve and pupae ants were "more buoyant" than the grown worker ants, according to the PLOS One paper.

The ant groups with no brood members to act as the bottom of the raft had more members that needed to be revived, the researchers found. But the ant-rafts that included brood ants had far fewer members that were "nonresponsive."

While the researchers had to factor in a few caveats, the experiment illustrated how ants have different roles within a colony and work together to survive.