The eye, broken down, can be looked at from so many perspectives of what makes it so amazing. For instance, the lens of the eye and the material it’s made of is able to refract light and focus it onto the back of our eye. Another impressive feature is the eye’s ability to cope with too much or a lack of light. Using small muscles, the pupil of our eye can expand and contract. The shrinking of the pupil occurs in order to prevent too much light from entering, while an expanding pupil allows more light in, making it easier to see in the dark.
So this is how light enters our eye, and how the eye regulates this, but how do we see all the different shapes and colors? How do light rays get translated into the things we visualize? Special cells on the back of our eyes called photoreceptors are the translators. In humans, there are four types of these cells. Three different cone cells, used for color receptors, and one type of rod cell, which is used for shape and movement. Thinking about what we see every day, it is almost unbelievable that these 4 cell types can produce the world around us. What if we had more than 4?In certain insects, that question is answered. Insects can range in the amount of photoreceptor cell types depending the insect in question. At most, some insects were studied and found to have 9 different types. How much more do they see than us? Butterflies in particular have been studied in depth regarding this phenomena. While they don’t see with the same clarity of humans, butterflies can see a different range of the electromagnetic spectrum. UV light is in their vision, and a comparison of what we see and what they see is shown in the following image.
Now the most photoreceptor cell types seen in a species was nine until just recently. A butterfly known as the common bluebottle, found in Australia, has been found to have 15! That is a whole six more photoreceptors, making researchers wonder what their vision must look like when being so sensitive to different wavelengths of light. More research needs to be done before conclusions can be made, but I think it’s safe to say that these eyes are pretty amazing.
- Chris Richard