This month’s question comes from…..
From Mrs. Gotschall’s 3rd grade class:
How do the dogs see and run at night?
Eyes All Aglow
By: Lynne Witte
Illustrated by: Jon Van Zyle
“In the full moon when it is blue and white on the snow at the same time, so bright and clean and open you could read a book, we harness the dogs and run at night.” Gary Paulsen writes in his book Dogteam, the dogs run a well-lit trail by the moon. But, what about those dark or whiteout snow conditions on a dog trail? Can the dogs see?
Yes, dogs can see. They rely on all of their senses to safely run at night, but we know they have better vision than humans. We know dogs see differently than their human driver because of the differences in the retina of a dog’s eye and the increased size of a dog’s pupil which allows more light to enter the eye. Dogs have something called a tapetum lucidum. Humans do not. The tapetum is a layer of reflective cells called rods behind the retina. The tapetum acts like a mirror in the dog’s eye. It reflects the light so a dog has another opportunity to see the light, which increases the opportunity for a dog to see an object in dim light. This reflecting light improves a dog’s vision and is why their eyes seem to glow colors in the dark. Because of the rod cells in the tapetum behind the dog’s retina, dogs have increased motion sensitivity as well. This allows dogs to see movement more clearly.
Dogs will travel a trail using increased vision and their keen senses of smell, hearing, and increased motion awareness. Mushers often compliment their leaders who ran through a whiteout or very dark conditions when humans have been struggling to see the trail. The dogs are focused on the smells, sounds, and motions along with their quality of vision at night to run!