Reading an issue of the science magazine Nautilus from a few years back, I came across this in a story on animal navigation by Sally Davies, pertaining to migratory birds:
Other studies point to the presence of a quantum mechanism in the eyes of avian migrants that enables them, perhaps literally, to see magnetic fields. An optical protein known as cryptochrome is thought to change into a quantum state when light strikes it, with two unpaired electrons zipping around two molecules in a configuration known as a radical pair. If these electrons spin in parallel, the system exists in what’s known as a triplet state; if they spin against each other, it’s known as a singlet. Running a magnetic field through this delicate biochemical web of subatomic particles will push the system towards either a singlet or a triplet state, depending on the direction of the field lines. The theory is that sensitivity to the balance of these states in the eye would allow the bird to perceive magnetic field lines, like a thread running through three-dimensional space, and use it to set their compasses for flight.
That's staggering. Birds might have quantum magnetic field detectors in their eyes? What would it be like to have that as part of your vision?
Animal navigation gets my attention because I am a man who can barely navigate his own house. GPS units and smartphone nav apps keep me from wandering for days trying to remember my way home. More on this topic coming soon.