Animal behaviour

Geomagnetic map used in sea-turtle navigation

These migratory animals have their own equivalent of a global positioning system.


Migratory animals capable of navigating to a specific destination, and of compensating for an artificial displacement into unfamiliar territory, are thought to have a compass for maintaining their direction of travel and a map sense that enables them to know their location relative to their destination1. Compasses are based on environmental cues such as the stars, the Sun, skylight polarization and magnetism2, but little is known about the sensory mechanism responsible for the map sense3,4. Here we show that the green sea-turtle (Chelonia mydas) has a map that is at least partly based on geomagnetic cues.

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Figure 1


Figure 2: Orientation of juvenile green turtles (straight carapace lengths, 29–47 cm) tested in magnetic fields replicating those at the sites marked by blue dots.


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Correspondence to Kenneth J. Lohmann.

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