What is the visible light spectrum and who is it visible to?

Many of us have learnt at school that the visible light spectrum is made up of seven colours ranging from red to violet. The colours being the same as the rainbows – red, orange, yellow, green, blue, indigo, and violet.


You may also have learnt that the visible section is only a tiny portion of the full electro-magnetic spectrum, and this spectrum includes Infra-red (next to Red) and Ultra-violet (next to Violet).












Source: Wikipedia. Click to enlarge


There are a collection of fascinating websites online that show what the world looks like to animals and insects that can see (or sense) portions of the light spectrum that we are unable to.


For example: bees can’t see red but can see ultra-violet. The usefulness of this becomes obvious when we learn that some flowers that we see as white, are perceived by the bee to include splashes of ultra-violet.


The ability to see ultra-violet is most common in fish, reptiles, birds, and insects. Most mammals have lost the ability to see ultraviolet light and lack the eye structure necessary to detect it (although some research suggests rats can see UV light).


Butterflies are thought to have the widest range, in terms of light they are able to perceive – some species of butterflies’ vision can range from near infra-red to UV. The markings that we already perceive as exotic and colourful, are even more so to the average butterfly.


Generally speaking, if an animal can perceive a portion of the range, this is in some way necessary for its survival. Whether that’s hunting, foraging for food, or finding mates.



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