Link #109: Arctic Hares Have Short Ears to Conserve Heat!



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Link #109: Arctic Hares Have Short Ears to Conserve Heat!

Arctic Hare by The Saylesman, (CC BY-SA 2.0)

Animals eat to survive. However, this survival is a combination of many things. For instance, eating is important because it gives animals the energy to evade predators, seek out more food and reproduce. However, there’s another reason for eating and that is body temperature management.

In our last post, we spoke about how colossal squids only eat about 30 grams of food per day because they live in such cold regions. In fact, the colossal squid eats only this amount of food despite being more than 30 feet long!

There are various ways through which animals in colder regions of the planet conserve heat. While the colossal squid eats less, the Arctic hare has evolved to have shorter ears! How does that help this cute and furry little animal conserve heat? Read on.

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How Do Shorter Ears Help Arctic Hares Conserve Heat?

Arctic Hare by The Saylesman, (CC BY-SA 2.0)

Have you ever tried to cool a liquid by putting it in a wider dish as opposed to a deeper dish? For instance, if you pour boiling water into a plate and the same amount into a glass to cool, you’ll see that the water in the plate cools faster. What this shows us is that there is a strong relationship between surface area and heat dissipation.

When the Arctic hares’ ears are compared to ears of other hare species, there’s a clear distinction in that the Arctic hares’ ears are shorter. This means that there is less surface area for an Arctic hare’s body heat to escape.

Since Arctic hares live in the coldest northern regions of North America such as Canada and the Northwest Territories along with Greenland and islands in the Arctic regions, these modifications are crucial to their survival.

What Else Do Arctic Hares Do to Conserve Heat?

In fact, the whole body of the Arctic hare has evolved in a manner to reduce surface area and increase body heat retention. Scientists say that Arctic hares’ bodies show lower surface area to volume ratio which means that they’re denser.

Arctic hares further help their cause by shrinking in extreme cold to reduce their body surface area even further. When it has to conserve energy, an Arctic hare will tuck in its paws and tail and sit still for hours on end.

If the need for heat conservation is even more severe, then Arctic hares will begin congregating. These congregations can be as small as a few individuals to as large as hundreds of individuals. In such congregations, Arctic hares snuggle up to each other to retain heat.

Arctic hares also enjoy a dual coat to protect them from the cold. They have an undercoat which is covered with an overcoat. The undercoat is very thick but is short while the overcoat is long and not as thick. The two coats combine to provide good insulation for the Arctic hare. The logic here is the same as two thin blankets being warmer for you as opposed to one thicker blanket.

When an Arctic hare senses danger, it stands up on its long hind legs to give its ears access to sounds so that it can run away if required.

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