Santa’s reindeer have the particularity of having a magical sleigh, but all members of the species have the particularity of having eyes that perceive ultraviolet light. This is confirmed by a study published this week.
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In their work, researchers from the University of St Andrews [article en anglais] in Great Britain and Dartmouth College in the United States remind us that reindeer have the particularity of feeding mainly on lichens, a species of mixture of algae and fungi, which grow at ground level. Problem: this food is not easy to spot visually during the Arctic winter because this gray or white lichen meal blends in with the snow. Furthermore, between September and April in this polar region, the sun remains below the horizon, and the day is in fact only a long dark blue twilight. So it’s not easy to see clearly.
And that’s where the reindeer’s magical eyes come into play. These researchers confirmed that their eyes have the particularity of seeing lichen in a color other than white as our human eyes see it, and as a result, this food stands out perfectly in the snow. How? Because unlike us, reindeer eyes have the particularity of seeing ultraviolet rays.
Result: for them, lichens, which absorb UV rays, appear as dark spots on the snow, which remains luminous since it reflects more UV rays. The fact that reindeer use their ultraviolet vision to detect food has been suggested in the past. But here, the researchers specifically studied how several species of lichens reflect UV at dusk. This is how they were able to imagine what a reindeer visualizes looking for food in the snow.
It is also quite common for animal vision to be different from ours. Cats see clearly with a brightness eight times lower than us, bees and certain birds also perceive UV rays. Some snakes perceive infrared radiation in the dark and finally an eagle in flight can zoom in on details in a way that makes all myopes dream: it can distinguish a very small object or animal on the ground, even 1.5 kilometers away. distance.