✦ The Spark
A mantis shrimp has 16 types of colour receptors — you have 3. It sees a version of the world you cannot even imagine.
The Story
Human eyes have three types of colour-detecting cells, called cones, tuned to red, green, and blue. From those three signals, your brain constructs every colour you've ever seen. The mantis shrimp has 16 types of photoreceptors — including receptors for ultraviolet and infrared light invisible to us.
Strangely, research suggests mantis shrimps don't process colour the way we do. Rather than blending signals together in the brain, they seem to recognise colours more like scanning a barcode — each receptor fires or doesn't. This is faster but perhaps less nuanced than human colour mixing.
What's truly mind-bending is that no human will ever see what a mantis shrimp sees. We don't have the neural wiring. We can describe the wavelengths scientifically, but experiencing those colours is completely beyond us — the same way a person born blind cannot experience "red" through description alone.
Make Your Prediction
How many types of colour receptors does a human eye have?
Pick your answer to reveal the explanation.
Today's Challenge
Look at a rainbow or a soap bubble and try to name every colour you can see. Now consider: a mantis shrimp looking at the same bubble might see at least five additional "colours" in between each one you named.
Talk About It
If you could add one extra colour to your vision that no other human could see, what would you want it to look like?
Does having more colour receptors mean the mantis shrimp experiences the world more richly than us?
If two animals see the same flower completely differently, which one is seeing the "real" colour?
Go Deeper
Mantis shrimps also have the world's most complex eyes structurally — each eye moves independently and can judge depth on its own, without needing a second eye. They can also detect polarised light, which helps them navigate and communicate.
Big Debate
If we invented glasses that let humans see ultraviolet light, should everyone be allowed to use them, or would seeing things others can't be unfair? Think about cheating in sports, or seeing things in private.