Amazing stuff!
"... But a new study has presented the first evidence that loggerhead turtles (Caretta caretta) use magnetic fields as a compass to determine direction and also use it to determine their geographical location.
There’s a little dance involved, too.
Sea turtles are extraordinary navigators, able to trace unseen pathways across thousands of kilometres of the ocean and return to the same feeding sites migration after migration. ..."
"... sea turtles returning to the same feeding sites again and again throughout their lifetimes — despite traveling up to 10,000 miles across the planet. ... hypothesized that these turtles used Earth’s magnetic field to memorize specific geographic areas that they associated with food ...
team conditioned loggerhead turtles to magnetic fields replicating those that exist in various oceanic locations, repeatedly feeding the turtles in some magnetic fields while not feeding them in others. When later exposed to the fields in which they were fed, the turtles exhibited “turtle dancing behavior,” indicating that they associated that specific magnetic signature with food. ..."
From the abstract:
"Growing evidence indicates that migratory animals exploit the magnetic field of the Earth for navigation, both as a compass to determine direction and as a map to determine geographical position. It has long been proposed that, to navigate using a magnetic map, animals must learn the magnetic coordinates of the destination, yet the pivotal hypothesis that animals can learn magnetic signatures of geographical areas has, to our knowledge, yet to be tested.
Here we report that an iconic navigating species, the loggerhead turtle (Caretta caretta), can learn such information. When fed repeatedly in magnetic fields replicating those that exist in particular oceanic locations, juvenile turtles learned to distinguish magnetic fields in which they encountered food from magnetic fields that exist elsewhere, an ability that might underlie foraging site fidelity. Conditioned responses in this new magnetic map assay were unaffected by radiofrequency oscillating magnetic fields, a treatment expected to disrupt radical-pair-based chemical magnetoreception, suggesting that the magnetic map sense of the turtle does not rely on this mechanism.
By contrast, orientation behaviour that required use of the magnetic compass was disrupted by radiofrequency oscillating magnetic fields. The findings provide evidence that two different mechanisms of magnetoreception underlie the magnetic map and magnetic compass in sea turtles."
Dancing turtles unlock scientific discovery (original news release)
Learned magnetic map cues and two mechanisms of magnetoreception in turtles (no public access)
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