Reindeer, or caribou in North America, have an incredibly unique genetic adaption to help them see better regardless of season or light condition. In the summertime, reindeer can be seen sporting a set of golden eyes, while in winter, they are a striking blue. Researchers have gotten to the bottom of this phenomenon.
The Arctic Tundra
Living in the arctic tundra has some extreme challenges for many species, but where many species may struggle to see long distances due to the unique light conditions in the biome, reindeer have developed their own way to combat this problem.
Unique Light Conditions
The Arctic has unique light conditions that change drastically depending on the seasons. In summer, there is perpetual daylight with little to no darkness, while in winter, things flip around, and the environment is swathed in darkness.
Comparing Their Eyes
Reindeer eyes have been examined by scientists and they’ve made a startling revelation about how and why they change color depending on the season. This change is more than just cosmetic and are an important adaptation to the change in light.
The Key To Their Adaptation
Neuroscientist Glen Jeffery was sent some reindeer eyes that were ethically sourced from local Sami herders. After dissecting them, he found the key to their unique adaptation – a reflective part at the back of the eye called tapetum lucidum. Once light travels through the eye, this layer bounces it right back, which improves their light vision significantly.
Golden Eyes
In the summer months, this reflective layer turns gold and reflects all of the available light back through the eye. This helps to make sure that there isn’t any overexposure of light in the retina and means the reindeer can see clearly even against full sunlight.
Blue Eyes
When the seasons change and reindeer is plunged in the dark winter months of the Arctic, the reflective layer at the back of their eye turns a stunning blue and scatters the light available inside of the eye rather than reflecting it back. This means that more light receptors in the eye can be reached, which lets it see in nearly pitch-black environments.
How They Change
The way that the animals are able to change their eye color is by shifting the spacing of collagen fibers inside of the tapetum lucidum. These fibers are compressed in winter, which reflects blue light, making the eyes appear blue. But there is a drawback to this adaptation.
A Compromise
Although this compression in winter allows reindeer to scatter light across their retina, giving them better vision when they need to spot predators and find food, this does come with a compromise. When they compress this reflective layer, sharpness is reduced, which means they cannot as clearly make things out.
Ultraviolet Vision
Ultraviolet lights are everywhere in the Arctic winter and may help animals find food obscured by snow or predators stalking them. The compression of the reindeer’s reflective layer could enhance their UV light vision, aiding them further in the dark winter.
The First Of Any Species
This unique change in their eye structure has been studied by researchers, and it is the first adaptation of its kind found in mammals. Jeffrey noted, “No one has ever seen anything like this in a mammal before, let alone such a large shift.”
Research And Discovery
The research and study of this adaptation has been on-going for many years, with researchers heading into remote places to ethically source the material to study. They typically purchase the samples from Sami herders, which means they are also involved in this groundbreaking research.
Future Studies
Future research into the reindeer’s unique adaptation aim to figure out just how much their UV light perception is changed by the tapetum lucidum compression. It could inspire future technology just as many animal adaptations have before.
Marvels Of Nature
The discovery of this genetic evolutionary trait has implications for other animals, and not just reindeer. It’s the first time scientists have found this adaptation, which means other animals could have similar game-changing traits that we have yet to discover. As science and research push forward, only time will tell what other marvels of nature will be uncovered.
