Humans have two types of receptor cells in our eyes to detect light - rod cells to detect the brightness of the light, and cone cells to detect the colour of the light by absorbing particular wavelengths. Together these determine how we see things in the world. Our cone cells can detect red, green and blue light, which allows us to see any colours in the visible spectrum, but what’s going on outside the visible spectrum?
While cats and dogs can’t see red light, they can see UV light, which we can’t. And so can birds: “Kestrels and hawks, for example, can detect where rodents have been because their urine trails reflect UV light,” says the latest episode of RiAus's A Week in Science. “It’s like a glowing map that shows their prey’s location from huge distances."
Butterflies and bees also have pretty amazing sight abilities, allowing them to see intricate shapes and patterns on flowers where we just see plain old colours. Watch the episode above to discover how it’s done.