We live in an enthralling world full of natural beauty and colour but not every species of animal views colour in the same way; this is because the colour of an object is determined by the sensory capabilities of the viewer and therefore is not set like size or weight. What we perceive as colour is actually the result of light hitting photorecepetors at the back of our eyes; these specialized cells then covert these light signals into brain signals that allow us to see the visual image. These photoreceptors can be catorgorised into two types rods and cones, the rods aid us with scopic (nightime vision) whilst cones are responsible for colour vision.
Inside the human eye there are 3 types of cone cell with each responding to different wavelengths of light i.e. short, medium and long and are named blue, green and red cones respectively, these cones are each triggered differently when light hits the eye and depending on how each cone responds for example the red may be stimulated more than green, the signals are then sent to and interpreted by the brain which builds the final colour image.
As humans have three types of cone cells we are said to have trichromatic vision however, most mammals have dichromatic vision and have only two types of cone cell which is blue and green sensitive. Old world monkeys and apes display trichromatic vision like us but new world monkeys appear to have sex linked colour vision, this means that females display trichromatic vision whilst males are dichromatic, some such as tamarins have females that can be both dichromatic and trichromatic. It is theorized trichromatic vision within new world monkey species may aid with foraging as red/green items will be easily seen or for same species communication whilst, dichromatic vision may be useful in areas of low light or when foraging for camouflaged food.
Most animal species such as reptiles, birds, some insects and fish can have tetrachromatic vision having four cone cells with the fourth cone cell being used to receive UV light but it is not uncommon for some to have 5 or more.
Note the dog view represents dichromatic vision whilst human represents trichromatic.
Note the bird vision represents tetrachromatic vision.
Now we can clearly see that tetrachromatic vision generates a colour spectrum wider than our own does this suggest that the more cone cells a animal species has that it should see and be able to discern between a wider colour range? Well a recent scientific study aimed to put this theory to the test using a marine species called the mantis shrimp (Haptosquilla trispinosa) which has 12 cone rods and should therefore be able to see far more colours than us humans can. To test this theory the scientists studied the shrimps ability to be able to discriminate between two colour types but instead of being able to easily differentiate colour difference the shrimps displayed worse results than what would be seen in humans, this was because the shrimp had developed over time a new way of perceiving colour signals, in which the photoreceptor outputs are sent directly to the brain instead of being pre-processed where, they are compared with a 'pre-set' template of colours to produce the final image; this process is thought to benefit the shrimp by less time being needed to process the image being received leading to a more rapid visual response.
The reality of the situation is however that as we will more than likely never be able to physically see through the eyes of other animal species, we will never really know or fully understand what it is like to view the world through their eyes but regardless of that the world is still a beautiful place when viewed through our own eyes and maybe we should therefore take more time to stop and admire its beauty more often.
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