World's second known animal that can find its way using polarized moonlight discovered

Why in the NEWS?

• Bull ants have been identified as the second known species to navigate using polarised moonlight.

Key Points:

• Recent research has shown that two species of night-dwelling bull ants, ‘Myrmecia pyriformis’ and ‘Myrmecia midas’, can navigate using polarised moonlight.
• This discovery is only the second known example of an animal using this mechanism, the first being dung beetles.
• The study, carried out at Macquarie University in Sydney, provides new insights into insect navigation and has potential implications for robotics, artificial intelligence and ecological research.

What will you read next in this topic?

1. The Role of Polarized Light in Animal Navigation
2. Experimental study on bull ants
3. Mechanisms of navigation in bull ants
4. Implications for science and technology

The Role of Polarized Light in Animal Navigation

Natural Light Sources for Navigation

• Many animals depend on celestial cues for navigation, including:
  • Sunlight – used for orientation by day-living species.
  • Starlight – used by migratory birds and nocturnal insects.
  • Moonlight – used by some night-living species to maintain direction.
• A key feature of these sources is polarized light, which provides an optical pattern in the sky that animals can recognize and use for navigation.

Understanding Polarized Moonlight

• Sunlight and moonlight are initially unpolarised but become polarized when scattered in the Earth's atmosphere.
• This polarization creates an e-vector pattern, which aligns with the position of the celestial body and can serve as a navigational guide.
• Until now, only dung beetles were known to use polarized moonlight for orientation.

Experimental study on bull ants

Research objectives and location

• The aim of this study, conducted at Macquarie University, Sydney, was to determine whether bull ants use polarized moonlight for navigation.
• The primary objective was to assess how these ants adjust their orientation under different lunar phases and artificially altered light conditions.

Methodology

• The researchers used the following techniques:
  • Used artificially polarized moonlight to test the ants’ response.
  • High-resolution tracking system to monitor movement patterns.
  • Lunar phase variation analysis to evaluate dependence on polarized light.
  • 45° rotation of the e-vector pattern to assess directional adjustments in ants’ movement.

Main findings

• Bull ants successfully used polarized moonlight to navigate under natural conditions.
• When the e-vector pattern was rotated, the ants adjusted their direction accordingly, confirming their ability to sense and interpret polarized light.
• Navigation efficiency varied across lunar phases:
  • Full moon - maximum reliance on polarized moonlight.
  • Crescent - partial use, with low accuracy.
  • New moon (no moonlight) - navigation errors increased significantly.

Mechanisms of navigation in bull ants

Multi-cue navigation system

• Bull ants employ an integrated navigation system, using:
  • Polarized sunlight during the day for orientation.
  • Polarized moonlight at night for orientation.
  • Olfactory cues to reinforce path memory.
  • Landmark recognition to enhance spatial awareness.

Responses to polarized light manipulation

• When the e-vector pattern was rotated 45° clockwise, the ants adjusted to the left.
• When rotated counter clockwise, the ants shifted to the right.
• This confirms that they actively track polarized moonlight for spatial orientation.

Lunar Cycle Dependency

Implications for science and technology

Advances in navigation and robotics

• Understanding how insects use polarized light could inspire biomimetic navigation systems.
• Applications in autonomous robots and AI-based systems could improve orientation in low-light environments.
• Potential breakthroughs in space exploration technology, where natural celestial cues could aid robotic motion.

Contributions to insect ecology and evolutionary biology

• The study enhances knowledge of insect sensory mechanisms and their adaptations to night time navigation.
• Future research may reveal similar capabilities in other arthropods such as bees, moths, and desert ants.

Broader ecological and environmental impacts

• The insights gained from this study could help understand how artificial lighting affects insect navigation.
• Conservation strategies could be developed to minimize human-induced disruptions to nocturnal ecosystems.