A Bird’s Eye View: Chickens See Colors Better Than You
Image Source: Wikimedia Commons. By: Baksteendegeweldige.
Chickens are enjoyed the world over, both as pets and as tasty meals. Beyond food, companionship, religious purposes or entertainment, not much is really thought of these flightless birds. Even though we may be higher than them on the food chain, they do have us beat in one area, at least: color vision.
Compared to the human eye, chickens have superior color vision, which can be contributed to a structurally well-organized eye. Researchers conducted a study that mapped 5 types of light receptors found in chicken eyes. They discovered that these receptors formed interwoven patterns, which increased the chicken’s ability to see many colors in any given part of the retina. The retina is the light-sensing structure located at the back of the eye. Use of this part is separated into 2 categories (at least): those with night vision rely on retina receptors called “rods”, while those with day vision rely on retina receptors called “cones”.
According to study author, Dr. Joseph C. Corbo:
“Based on this analysis, birds have clearly one-upped us in several ways in terms of color vision. Color receptor organization in the chicken retina greatly exceeds that seen in most other retinas and certainly that in most mammalian retinas.”
Corbo believes this enhanced color vision may be owed to the fact that birds did not spend a period of their evolutionary history in the dark. One example of this would be the age of the dinosaurs—a time when most mammals became nocturnal for millions of years. Birds are viewed as evolutionary descendants of dinosaurs and as such, never spent such a time in the dark as other animals did. Thus, birds have more types of cones than mammals.
Corbo goes further to explain things:
“The human retina has cones sensitive to red, blue and green wavelengths. Avian retinas also have a cone that can detect violet wavelengths, including some ultraviolet, and a specialized receptor called a ‘double cone’ that we believe helps them detect motion.”
Further results of the study (published in PLoS One) show that most avian cones have a special structure comparable to “cellular sunglasses”—basically a lens-like drop of oil inside the cone that can filter out quite a lot, except for a specific range of light. The researchers used these drops to define the location of different cones found on chicken retinas. Although different types of cones were evenly distributed, there were never 2 of a kind located next to each other. Corbo noted that the birds’ heightened color sensitivity may help them find mates or food, since both involve an array of color.
More eye studies can certainly be expected in the future. Researchers intend to study how organization of the eye is established, at the very least. Corbo believes such insights could help stem cell (and similar) scientists treat a number of disorders that can cause blindness. In any case, the next time you see a chicken on a farm (or perhaps on your dinner plate), you may view them in a completely different light—or at least, that’s how they’ll most certainly see you.
By Heidi Marshall
I have been with GreenFudge for about a year now, but I've had a passion for Nature my entire life. When I'm not writing articles, you can find me out hiking, gardening, working on green craft projects, or taking photos for my website. You can check out the site at http://arkisaeo.com
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Tags: avian, birds, chickens, color vision, cones, double cone, eyesight, research, retinas, study
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