Many animals use the Earth's magnetic field for orientation and navigation. The most famous are probably migratory birds, which have been studied extensively, but others with this ability include select insects, fish, reptiles, and mammals.
Scientists attribute birds' magnetic sense to cryptochomes, light-sensitive molecules. Cryptochromes are a class of flavroproteins that are sensitive to blue light. They're involved in the circadian rhythms of plants and animals, and for some species, in the sensing of magnetic fields. Birds have cryptochrome 1a in their eyes' photoreceptors, which are activated by light to react to the magnetic field. But could our pups have this same ability?
Researchers from the Max Planck Institute for Brain Research have recently detected cryptochrome 1 (the mammal equivalent to the birds' cryptochrome 1a) in the photoreceptors of several mammal species, making it possible that these animals may also have a magnetic sense that is linked to their visual system. Out of 90 mammal species that they looked at, they only found cryptochrome in a few species from the carnivore and primate groups. This included dog-like carnivores, such as dogs, wolves, bears, foxes, and badgers, but not cat-like carnivores, such as cats, lions, and tigers.
It's possible that the cryptochrome could control other functions, like circadian rhythms or help with color perception, but because of their location the researchers believe that this is unlikely. The cryptochrome is located in the blue- to UV-sensitive cone photoreceptors, just like the birds.
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There is other evidence that dogs and other similar species can perceive the Earth's magnetic field. For example, foxes are more successful at catching mice when they pounce on them in a north-east direction.
However, this is not to say that the cryptochrome is the only indicator of sensitivity to the Earth's magnetic field. Rodents and bats react to magnetic fields, but don't contain active cryptochrome.
The scientists hope to further explore this finding and discover if dogs do have the ability to sense the Earth's magnetic field.