New research compiled by an international team suggests that reindeer can see ultra-violet light. Unlike humans, reindeer do indeed respond to ultra-violet stimuli. The scientists suggest that their UV abilities may enable them to see better in the “UV-rich” landscape of the arctic.
UV light is completely invisible to humans. It has wavelengths shorter than visible light that can range anywhere from 400 nanometers to 10 nanometers. The researchers fired UV light of about 350 nanometers into a dissected sample of a reindeer eye sample and the light passed through; giving them further incentive to keep studying.
Details of the Study
Glen Jeffrey, from the University College London and co-author of the study, goes on to describe in detail the scientists did: “We used what is called an ERG (electroretinography), whereby we record the electrical response to light by the retina by putting a little piece of gold foil on the inside of the eyelid.” The tests revealed that the photoreceptor cells in the retinas responded to the UV light.
The scientists think that their ability to see UV light plays a huge role in their survival; allowing them to see predators and food in the white Arctic winter.
They also cite two particular examples in which this is definitely the case: Lichens, which the reindeer eat, would appear black against the snowy backdrop because they absorb UV light. Wolves would also appear darker because their fur absorbs UV light, giving the reindeer better chances for survival against the predator.
Animal urine would be highly visible as well, letting the reindeer know that predators or other reindeer are nearby. When tested for damage, the reindeer didn’t appear to suffer any as the result of seeing UV light. The animals are also not susceptible to the snow blindness that can occur in humans.
Lars Chittka, from Queen Mary University London and who also has done interesting UV research, notes that studies like this one exemplify the reality that the “visible” spectrum doesn’t apply to many animals. “It’s further evidence that UV sensitivity across animals is the rule rather than the exception, and that humans and some other mammals are actually a minority in not having UV sensitivity,” he said.
Chittka also noted that more tests should be done to determine whether or not their UV abilities actually help the reindeer identify predators and food.
The research team that headed this experiment is planning another very soon, this time with seals. Professor Jeffrey thinks that it is likely that many animals in the arctic possess the ability to see UV light. He says, “There’s no evidence that Arctic foxes or polar bears suffer from snow blindness, so I bet you that most of the Arctic animals up there are seeing into UV.”
It would certainly make sense if it was discovered that more arctic animals possessed this ability. It also goes to show that although we have made groundbreaking discoveries about different animals, we are still nowhere near the peak of what we can learn.