India, May 24 -- It's easy to make the mistake of assuming that all animals experience the world as we do.

The truth is that, beyond our version of reality lies a world of eyes that see differently, sounds we cannot hear, and colours we can barely imagine.

Reindeer, for instance, can see ultraviolet light. (Imagine what the Aurora Borealis looks like to them.)

They actually rely quite heavily on this ability. Because both animal urine and lichen absorb UV light, the reindeer can use their special receptors to detect the former, which helps them avoid predators and court potential mates, and find the latter, so they can stay alive in winter.

Both appear as sort of anti-beacons: dark blotches against bright, reflective snow.

Birds and ...