Born to Run

How are animals of Beringia, such as sled dogs, adapted to the environment?


Getting the life-saving serum to Nome in 1925 when the diphtheria disease broke out in this area, called for a reliable form of transportation that would not break down with mechanical failure and would not depend on good conditions, weather or otherwise. Sled dogs can run and function optimally within the context of the Arctic environment. Adaptations are physical characteristics or behaviors that help an organism, or living thing, survive in its environment.  What are the adaptations of a sled dog body that make their bodies so perfectly adapted to covering long distances in cold dry conditions?

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1) As a group or individually, read the “five adaptations” that sled dogs have developed which makes them thrive in the cold Arctic environment. Identify each of the five body parts as an ‘adaptation’ for students to grasp this concept.

2) Create teams of 2-3 students in each. Each team choose (or is assigned) an animal and an environment (ie desert, forest, jungle,
coastline, tundra, ocean, mountain, island, etc).

3) Student groups make a list of at least three adaptations that their animal must have in order to survive in the environment assigned.

4) For each of the adaptations listed, have the students decide if each adaptation is a Behavior (the way the animal behaves or acts), Form (the way the animal is built), or Function (the way the animal works).

5) Share group findings as a class.

Key Adaptations

Five primary adaptations that sled dogs have developed to live and work in the bitterly cold winters of Beringia; specifically the dog’s tongue, feet, fur, circulation, and tail.

• Tongue: Dogs get rid of excess body heat by panting. Cold air is inhaled through the mouth and nose,
and then warmed up in the lungs. The warm air is then exhaled. As the air is exhaled over the dog’s wet
tongue, the water evaporates cooling down the tongue, losing excess heat in the process. The more heat a
dog needs to lose, the faster it will pant.

• Feet: Sled dogs have special kind of body fats in the pads of their feet. Saturated fats, like butter, stay
solid in cold temperatures. Unsaturated fats, like olive oil, are liquid at cool temperatures. The special
blends of fats in a sled dog’s paws stay liquid and pliable at colder temperatures than the rest of the fats in
their body. Combined with the tough skin covering their pads, this special type of fat prevents freezing and

• Fur: Sled dogs have two coats of fur that make them adapt to cold weather. The guard hair is the outer
layer of fur that is what we see and pet. The guard hairs repel water to help keep the dog dry. The
underfur is the coat that is made of shorter, fluffier fur close to the dog’s skin. The underfur provides
insulation from wind and cold and prevents heat loss.

• Circulation: Sled dogs have developed a special circulation system in their bodies that helps dogs
conserve the heat carried by blood. Heat travels from warm blood inside the arteries to the cooler veins
surrounding them. As a result, the cool blood returning from the feet gets reheated before it gets back to
the body core. This heat exchange saves the sled dog a lot of energy from having to heat up very cold
blood in their body. It also keeps the muscles of the legs warmer, which helps speed recovery from sore
muscles or injuries.

• Tails: Sled dogs have big, bushy tails. On the trail, sled dogs sleep outside on the snow. They curl up
into little balls, tucking their noses and feet under their bushy tails. When the dogs breathe out, the warm
air is trapped by their furry tails warming the air they breathe in.

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