Moonlight Helps Nighttime Ants Find Their Way Home

Greg Howard
10th December, 2024

Moonlight Helps Nighttime Ants Find Their Way Home

This experiment tested whether the large-eyed bull ant (Myrmecia midas) navigates using polarized moonlight by rotating the overhead light pattern with a filter to measure changes in their homing paths (a), at nest sites with open canopies (b), and throughout different lunar phases (c).

Image adapted from: Freas et al. / CC BY (Source)

Key Findings

  • Researchers at Macquarie University found that nocturnal bull ants use the dim polarisation pattern of moonlight to navigate at night
  • The ants changed their direction in response to manipulated polarisation patterns, showing they rely on this pattern for orientation
  • This discovery suggests that the ability to use polarised light for navigation may be more common among nocturnal animals than previously thought
The study of animal navigation has long fascinated scientists, with various species exhibiting remarkable abilities to orient themselves using celestial cues. Recent research conducted by Freas et al. at Macquarie University[1] has unveiled a groundbreaking discovery in this field: nocturnal bull ants (Mymecia midas) use the exceedingly dim polarisation pattern produced by the moon for overnight navigation. This finding adds a new dimension to our understanding of how animals navigate in low-light conditions and builds on previous studies that have explored similar mechanisms in other species. Light travels through space as waves, oscillating in various orientations. When these light waves enter the Earth's atmosphere, they become polarised, meaning they oscillate along a single plane. This polarised light creates a predictable pattern in the sky, which is imperceptible to humans but visible to many animals. During the day, sunlight produces a polarised light pattern that serves as a reliable compass for navigating animals[2]. However, the moon also reflects sunlight, creating a similar, albeit much dimmer, polarisation pattern at night. Previous studies have shown that dung beetles use polarised moonlight for navigation. For instance, the dung beetle Scarabaeus zambesianus relies on the moon's polarisation pattern rather than the moon itself for orientation[3]. Similarly, the nocturnal ball-rolling dung beetle Scarabaeus satyrus maintains accurate orientation using the polarisation pattern around the moon, even under crescent moon conditions[4]. These findings highlighted the role of polarised light in nocturnal navigation but left open the question of whether other nocturnal animals, such as ants, use similar mechanisms. To address this question, Freas et al. conducted experiments to determine whether nocturnal bull ants could detect and use polarised moonlight for navigation. The researchers used polarisation filters to rotate the polarisation pattern in the night sky above two bull ant nests. They observed that the forager ants altered their direction in line with the change in the polarised pattern, demonstrating that they were using this pattern to navigate. This ability to detect and respond to polarised moonlight even when the moon was below the horizon or only partially visible indicates an extremely high visual sensitivity in these ants. This study is significant because it is the first to show that an animal other than dung beetles can use polarised moonlight for navigation. The findings suggest that the ability to detect and use polarised light patterns for orientation may be more widespread among nocturnal animals than previously thought. The study also supports the idea that animals can flexibly switch between different celestial cues based on the availability and reliability of these cues in their environment[5]. The implications of this research extend beyond understanding animal behaviour. The discovery that polarised moonlight can be used for navigation opens up new possibilities for developing navigational systems for robotics. By creating polarisation sensors with sufficient sensitivity, it may be possible to design sky compasses that can navigate both at night and during the day, offering potential applications in various fields, including autonomous vehicles and exploration technologies. In conclusion, the research by Freas et al. at Macquarie University provides compelling evidence that nocturnal bull ants use the dim polarisation pattern produced by the moon for navigation. This discovery builds on previous studies of polarised light navigation in dung beetles[3][4][5], expanding our understanding of the mechanisms underlying nocturnal navigation in animals. The findings not only enhance our knowledge of animal behaviour but also hold promise for the development of advanced navigational technologies.

EnvironmentEcologyAnimal Science

References

Main Study

1) Polarised moonlight guides nocturnal bull ants home.

Published 9th December, 2024

https://doi.org/10.7554/eLife.97615

Related Studies

2) Varieties of visual navigation in insects.

https://doi.org/10.1007/s10071-022-01720-7

3) Lunar orientation in a beetle.

Journal: Proceedings. Biological sciences, Issue: Vol 271, Issue 1537, Feb 2004

4) How dim is dim? Precision of the celestial compass in moonlight and sunlight.

https://doi.org/10.1098/rstb.2010.0191

5) Neural coding underlying the cue preference for celestial orientation.

https://doi.org/10.1073/pnas.1501272112


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