How ants find their way home
The ability to navigate around the environment is fundamentally important to all animal, both large and small. Scientists traditionally believed that ants relied on path integration (PI) when in unfamiliar terrain and then upon on learnt visual information as they become more experienced. Using PI, ants are constantly up-to-date about their position relative to their nest by monitoring information about distance and direction travelled. Learning and using visual cues, in addition to PI, makes navigation more efficient and robust, and recent research suggests that the ants’ navigational toolkit is more diverse, such as using olfaction for orientation as well as visual cues and PI. The EU-funded ANT NAVIGATION project investigated in fine detail ants’ movements in order to identify the computational strategies used for multi-modal navigation. These strategies are the key to understanding navigational mechanisms and how behaviour results from the interaction between brain, body and the environment. Researchers first examined in detail the paths taken by navigating desert ants using PI and interactions with other sensory cues. They found that the slower the ants walked the more receptive they were to both familiar and unfamiliar visual cues. In addition, it appeared that walking speed positively influenced the ants’ accuracy in both the use of vision and PI. Exploration of the interaction between vision and olfaction in naive and experienced ant foragers revealed that wood ants can pinpoint an inconspicuous feeding site by following the odour plume. Experiments also showed that the paths of ants navigating purely by olfaction are more winding and therefore longer. The addition of the visual cue made these paths shorter and the walking speed increased, but it does not achieve the straightness seen in ants using vision alone. ANT NAVIGATION provided valuable insights into the spatial computations underlying navigation. By understanding the mechanisms behind multimodal interactions scientists will achieve a more profound understanding of how insects, with their small brains, can perform sophisticated navigational behaviours. This will lead to better designed small autonomous robots.
Keywords
Ants, path integration, olfaction, ANT NAVIGATION, sensory cues
