To survive the dark, snowy arctic winters, reindeer have evolved a unique visual system. Their eye color changes to adapt to the large fluctuations in sunlight during arctic summer and winter, but may further help them find food.a The study was published Dec. 15 in the journal i-Perception They discovered that their eyes may have evolved to see light in the ultraviolet spectrum to help them find their favorite foods in dilapidated homes.
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Reindeer mainly eat Cladonia rangiferina (C. Rangifelina), which is appropriate Also known as reindeer moss. This plant is not a moss, but a type of algal fungus called a lichen. It forms a thick, crunchy blanket on the ground throughout the Earth’s northern latitudes, important role It is integrated into the ecosystem as a food source.
inside studythe team worked at cairngorm mountains Located in the Scottish Highlands, home to Britain’s only reindeer herd. Reindeer were locally hunted to extinction, but they began to become extinct. Reintroduced from Scandinavia in 1952.The Cairngorms is home to more than 1,500 species of lichen, but the reindeer here rely on C. Rangifelina during the winter
“What’s unique about reindeer is that they rely on this type of lichen,” says study co-author Nathaniel Dominy, an anthropologist and evolutionary biologist at Dartmouth College. stated in a statement. “It’s rare to find such a large mammal, let alone an animal that survives by eating large amounts of lichen.”
The white lichen on the snow is invisible to the human eye. However, co-authors Katherine Hoveriter and Julie Harris of the University of St. Andrews found that: C. Rangifelina and other Lichen species that supplement reindeer food absorb ultraviolet (UV) light. Using spectral data from lichens and light filters created to mimic reindeer vision, the researchers found that to reindeer, plants can appear like dark specks against a bright landscape. discovered. They stand out like spots on a Dalmatian, making them easy for reindeer to spot.
Dominey said this is one of the first studies to use a visual approximation of how these mammals see their world.
“If you can look out at this white landscape and think about how they feel, you want a direct route to food,” Dominey said. “Reindeer don’t want to waste energy wandering around looking for food in cold, barren environments. Being able to see lichens from a distance allows them to save precious calories when food is scarce.” There are huge benefits.”
Animals that can be seen in the UV spectrum include: Dogs, cats, pigs, and even ferrets. They usually do this by: short blue photoreceptors called cones Exist in their eyes.
previous research The reindeer’s eyes have been shown to turn golden in the summer and bright blue in the winter. The light-enhancing membrane that gives many animals glowing eyes is tapetum It changes depending on the season. The blue hue of their eyes is thought to amplify the low levels of sunlight present during polar winters.
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“If the light color in the environment is predominantly blue, it makes sense for the eyes to emphasize blue to ensure that the reindeer’s photoreceptors are maximizing that wavelength.” Mr. Dominey says.
But the blue tapetum also Allows up to 60% of UV rays to pass through. For the color sensor of the eye. Reindeer may see the winter world as shades of purple, just as humans see a room under a black light. Snow and other surfaces that reflect UV light shine brightly, while surfaces that absorb UV light darken.
Scientists investigated why diurnal Arctic animals have eyes that are highly receptive to ultraviolet light that reflects off snow. This research suggests that the answer to this question is tied to: C. Rangifelina The same goes for other lichens, as UV rays are not reflected from those organisms. The researchers believe reindeer eyes may be optimized to pick out lichens when they are most difficult to find, since they are a staple food source.
