Is it true that the northern deer change the color of the eyes depending on the season?

On the Internet, publications about the unusual anatomical feature of the northern deer are popular. We checked the reliability of such messages.

The fact that the color of the eyes in these animals differs in winter and summer, also write publics in "VKontakte"and users Facebook, Twitter, Instagram, "Yandex.Zen", Pikabu, Livejournal and other social networks and a blog-platform. Similar statements can be found on sites "Interesting facts" And "Big question".

This feature of the northern deer is also told in much more authoritative sources. For example, on the website of the Museum of Natural History in London represented Note on an unusual collection of eyes cut in half. The eye of the northern deer in the publication is called a “scientific miracle”, because it changes its color from golden to dark blue as the summer is replaced in winter.

Biologists became aware of this feature not so long ago. In 2013, Glenn Jeffrey from the Institute of ophthalmology of the University College of London (UCL) introduced The results of his study conducted in conjunction with Norwegian University Tromso. In an interview with National Geographic Jeffrey tellsthat I wanted to understand how animals living in the Arctic adapted to a sharp change in the level of illumination depending on the season. His colleagues from Norway in 2000 sent him a “bag with the eyes” of deer killed by the Sami at different times of the year. During the preparation of Jeffrey, it was very surprised that the eyes of different groups were inside different colors. After 13 years of research, he, along with his colleagues, published the results of his research.

Like many other animals, in the eye of the northern deer there is a layer of fabric (Tapetum Lucidum), which is behind the retina and reflecting the light back on it, which helps them see in the dark. We see the “work” of this layer when we look at the cat in the dark - it seems that when the light hits her eyes, they seem to begin to glow. In most animals in the bright light, Tapetum Lucidum is painted with a golden color, because most of the world is reflected directly through the retina. In the northern deer closer to winter, this layer becomes dark blue. This helps them to notice a predator in time in winter darkness in time, because their vision It becomes Even less sharp, but a thousand more sensitive to the light.

Glenn Jeffrey suggests: This feature can be caused by the fact that in winter, due to the constant expansion of the pupils, the pressure in the eyes of deer grows, preventing the natural outflow of liquid from the eyeball. This, in turn, compresses Tapetum Lucidum, consisting mainly of collagen fibers located with ordered rows. The distance between these fibers becomes significantly smaller, and the layer of fabric, thus, reflects the shorter waves of blue light characteristic of the Arctic winter. However, although the color change of tapetum lucidum is observed empirically, not all scientists agree With the proposed explanation.

However, many users of social networks and some journalists, talking about this feature, miss an important detail. The Tapetum Lucidum layer, which is responsible for changing color, is located for A retina - we can see it only by cutting the eye. “The front part of the eye looks the same in summer and winter,” reported Jeffrey Facturers from USA Today, so many photos accompanying the story of an interesting fact are not true. In other words, the northern deer do not “change the color of the eyes” just like a person who has an operation to change the color of the iris or wears colored lenses.

Photo on the cover: Jellisv / Istock

Half truth

What do our verdicts mean?

Read on the topic:

1. National Geographic. Who are reindereer eyes golden in summer but blue in Winter?
2. UCL. Reindeers' Eyes Change Color with Arctic Seasons
3. USA Today. Fact Check: Reinder Eyes Change Color Threugh Seasons, Butse Photos Donat Show The Phenomenon
4. Is it true that in Finland the deer paint horns with reflective paint to reduce the number of accidents with them?