Ants Use Polarised Moonlight for Navigation
Bull ants (Myrmecia pyriformis and Myrmecia midas) rely on polarised moonlight for orientation, making them the second species to be discovered using this method, after dung beetles.
Polarised moonlight, although dimmer than sunlight, contains distinct patterns that help guide the ants' movements, especially when they are foraging at night.
The ants can detect these patterns throughout the entire lunar cycle, which allows them to stay on course even when cloud cover or obstructions, like tree canopies, limit visibility of the moon.
Polarisation and E-Vector Pattern
Polarisation occurs when light scatters in the atmosphere, causing the electric field of the light waves to align in a specific direction.
The e-vector pattern formed by this polarised light helps provide consistent directional cues, acting as a compass, which the ants use to navigate with remarkable precision.
The pattern is particularly helpful near the horizon, where polarised light is more stable and easier for ants to detect.
It runs parallel to the north-south axis, aiding the ants' orientation during both sunset and moonrise.
Ant Navigation Under Different Lunar Phases
Ants show the most accurate navigation during the full moon
During the waxing and full moon, their path adjustments are higher, ensuring more reliable guidance.
In the waning phases or new moon, when moonlight is weak, the ants’ heading shifts decrease, showing they rely on stronger moonlight for orientation.
During the new moon, when no moonlight is visible, ants fail to use polarised light for navigation
Unique Behaviour and Implications for Future Research
The study suggests ants may have a time-compensated lunar compass, adjusting their direction based on moon position and time of night.
Future research could explore whether ants use additional cues like visual landmarks to update their orientation, similar to other insects like honeybees and desert ants.
This study opens up new research on how nocturnal insects navigate in low-light conditions and whether other species also use polarised moonlight for guidance.
COMMENTS