Superheroes have long been endowed with super-senses on top of what mere mortals have. (Think: Superman’s X-ray vision!) But what if Fido also had a superpower?

Cryptochromes are light-sensitive flavoprotein molecules found in all kinds of living organisms, from bacteria to plants to animals. In animals, they're part of the mechanism that regulates the circadian rhythm, commonly known as the “biological clock” because it produces physical and mental changes in sync with the 24-hour day-night cycle. (In fact, that's what causes jet lag.)

This is what a cryptochrome molecule looks like inside protein modeling computer software. This is what a cryptochrome molecule looks like inside protein modeling computer software. (Photo: Protein Data Base/Wikipedia)

We know that a special cryptochrome found in the blue-sensitive cones in the eyes of birds allows them to orient themselves using the Earth’s magnetic field, which helps explain how they can fly such long distances without getting lost. A magnetic sense has also been observed in some insects, fish and reptiles. (This sense is notably missing in humans.)

But what if this superpower was more widespread than we previously thought? Researchers at the Max Planck Institute for Brain Research in Frankfurt investigated the presence of the mammalian equivalent of the bird’s special cryptochrome in the retinas of 90 mammal species. As reported in Nature Scientific reports, the researchers only found the magnetic sensors in some species.

Dogs, wolves, bears, foxes and badgers had the “cryptochrome 1” molecule. But cat-like carnivores like cats, lions and tigers didn’t have the molecule. Among primates, orangutans, rhesus macaques and crab-eating macaques also tested positive for the molecule.

Orangutan have active cryptochrome 1 molecules inside their retinas.Orangutans have active cryptochrome 1 molecules inside their retinas. (Photo: Kabir Bakie/Wikipedia)

In the positive carnivore and primate groups, the molecule is located in the blue-to-UV-sensitive photoreceptors in the retina and reacts to magnetic fields only if it's simultaneously excited by light.

But what does that mean? As Gizmodo explains:

It’s not immediately obvious how mammals like dogs and primates use their magnetoreception, but foxes may provide a clue: When hunting, foxes are more successful at catching mice when they pounce on them in a northeast direction. For primates, this built-in compass may help with bodily orientation, or it could be a vestigial evolutionary trait that’s largely unused.

Researchers don’t believe these molecules are related to the animals’ circadian rhythms because they aren't found in the right cell location for that function.

So do our furry friends really have a sixth sense? Further research will be required to know — as we can't be certain that the cryptochromes that were discovered are used to perceive the Earth’s magnetic field — but it looks like a real possibility.

Michael Graham Richard ( @Michael_GR ) Michael writes for MNN and TreeHugger about science, space and technology and more.

Dogs and primates might have a 6th sense that allows them to see magnetic fields
The world must be quite different for animals if they can perceive magnetic fields.