Paws Along the Trail with Light
What arctic animal might a sled dog team encounter along the Iditarod Trail? Moose? Bison? Likely.
Polar Bears? Unlikely, yet possible along the coast.
I happened upon these Christmas ornaments in a store and was troubled by penguins paired with a Native Alaskan and a polar bear. Both ornaments represent a common misconception.
The problem with both is the presence of penguins, which reside only in the southern hemisphere. A lesson on light and guard hairs on polar bears and sled dogs can be kicked off with a discussion of “What is wrong with these ornaments?”
We know that sled dogs have double coats of fur, the undercoat that keeps them warm and the guard hair coat that serves multiple purposes. First it prevents ice and snow building up when it’s cold and windy. The guard hairs also “act as a barrier to repel water and catch dirt and debris.” [“Understanding a Dog’s Double Coat” mybrownnewflies.com] The guard hair also prevents superficial injuries and gives an additional layer of stiff insulation against the cold.
Arctic animals have these double coats. A polar bear’s outer coat is especially interesting. It has been reported that even night-vision glasses do not detect polar bears. This is because no radiating heat escapes their hair, which is what night vision goggles pick up. I have included a lesson for students to study and create a model of how the polar bear’s guard hair works. It’s a good resource for reading research and a study of light reflection.
Light Reflection Lesson Plan