Desert ants of the species Cataglyphis nodus have an extraordinary talent for navigating their sparse and featureless habitats, and now, scientists have uncovered a surprising twist: these ants use the Earth’s magnetic field to help them find their way.
However, unlike other insects such as monarch butterflies, the new research reveals that desert ants rely on a different aspect of the geomagnetic field for navigation.
The research, led by Dr. Pauline Fleischmann from the University of Oldenburg in Germany, reveals that these ants detect the polarity of the magnetic field — the north-south direction — rather than the inclination or the angle between the magnetic field lines and the Earth’s surface, which many other species use.
“This type of compass is particularly useful for navigation over comparatively short distances,” Fleischmann explains.
The study, published in the journal Current Biology, resulted from a collaboration between researchers from the University of Würzburg, Germany, and the Norwegian University of Science and Technology.
Using Magnetoreception
The researchers conducted their experiments using desert ants from a colony in Greece. The ants were exposed to altered magnetic fields created by Helmholtz coils placed around their nests. This setup allowed the team to observe the ants’ behavior as they performed “learning walks” — a unique behavior where ants leaving their nest for the first time repeatedly stop and orient themselves, memorizing the direction of the nest entrance.
The study showed that altering the polarity of the magnetic field caused the ants to misjudge the location of their nest. However, changing the field’s inclination did not affect their behavior.
This discovery highlights that desert ants rely on the north-south polarity of the geomagnetic field for short-distance navigation, unlike monarch butterflies and songbirds that depend on inclination for long-distance migration.
The researchers concluded that the desert ants likely use a particle-based magnetic sense. This mechanism involves tiny magnetic particles, such as the mineral magnetite, in their sensory or nerve cells.
“This suggests that ants use a different mechanism for magnetoreception than most insects studied to date,” Fleischmann notes.
This finding opens the door to studying the evolution of magnetoreception in the animal kingdom, particularly in insects like ants, bees, and wasps, which all belong to the Hymenoptera order.
Remarkable Navigational Skills
Desert ants are already renowned for their exceptional navigational abilities. In the arid salt pans of the North African Sahara or the sparse pine forests of Greece, where landmarks are scarce, these ants can travel hundreds of meters from their nests in search of food. They employ a zig-zagging search pattern to locate food and then return home in a straight line.
Paralyzed Mice Walk Again
“This research not only enhances our understanding of the sensory world of ants but also offers new perspectives on how magnetoreception has evolved in different species,” Fleischmann concludes.
Other Magnetic Navigation
Many animals across the animal kingdom rely on the Earth’s magnetic field to navigate, often with astonishing precision. Migratory birds, such as songbirds, are thought to use a light-dependent quantum process known as the radical-pair mechanism to detect the inclination, or angle, of magnetic field lines, which helps them travel vast distances.
Similarly, sea turtles are known to navigate across entire oceans by sensing variations in the magnetic field, likely using particle-based magnetoreception involving tiny magnetic particles, such as magnetite, embedded in their sensory or nerve cells.
Pigeons, bats, and even some fish are believed to use similar mechanisms to orient themselves during migration or to locate specific destinations. Dogs also use the Earth’s magnetic field, but not for navigation, as a 2014 study showed that they often use these magnetic field lines to guide where they poop!
These abilities highlight the diverse evolutionary adaptations animals have developed to survive by using the planet’s invisible geomagnetic map.
Kenna Hughes-Castleberry is the Science Communicator at JILA (a world-leading physics research institute) and a science writer at The Debrief. Follow and connect with her on BlueSky or contact her via email at kenna@thedebrief.org