Ants keep what could be considered a scrapbook of images that help guide them back to their nest from distant foraging sites. Scientists discovered ants take mental images of landmarks around the nest that serve as a navigational tool.
Scientists from The Vision Center and the Research School of Biology at the Australian National University experimented with Australian jack jumper ants traveling from trees to their nest to discover how the insects navigate. The study was published in the journal Proceedings of The Royal Society B. According to the news release, the ants typically travel from their nest to a tree where they hunt prey.
The jack jumper ant is a species of the bulldog ant and it gets its name from the hopping motion it performs when agitated. The ant stings prey with venom and live in underground nests, typically under rocks.
According to Dr. Ajay Narendra, from the Australian National University, ants typically have two navigational methods to guide them back to the nest. The first method involves path integration, an imagined course back to the nest based on distance and direction, while the second involves images of landmarks near the nest. The scientists captured a group of jack jumper ants from a foraging site, fed them and released the insects at a different location at least 10 meters from the nest, according to the release.
After the ants returned the nest, the scientists once again captured the ants and released them at a different location that the previous release location. According to Dr. Jochen Zeil, also from the Australian National University, the ants, instead of being confused, quickly found their way back home. In fact, in the second test, the ants returned to the nest quicker than the first test. Dr. Zeil said the ants should have taken longer as they would have needed to adjust their navigation system to return to the nest, using either path integration or landmarks. The reason for this improvement is due to the reliance on mental images of landmarks.
“They left the release sites, briefly scanned their surroundings, made a decision and headed in the right direction to the nest,” said Dr. Narendra. The ants were slower to return to the nest in the first experiment because the unfamiliar release location did not correspond with the imagined course that ants had originally set up while the landmarks provided the correct course back to the nest.
In the second experiment, the ants simply used the mental images of landmarks to observe their surroundings and return to the nest. There was no path integration data as the scientists had transported the ants to a release site and the ants were not plotting a course to a foraging site like in the first experiment.
The experiments led the scientists to conclude that ants collect mental images of the area around the nest from different angles and directions. The ants then use this archive to return to the nest by simply comparing their current view with the stored images.
Previous research involving honeybees led scientists to believe they used a map to travel but this new experiment indicates an insect can rely on imagery as a navigational tool. According to Dr. Narendra, maps can be too complex to store and using landmarks is simple but effective.