Navigation
A look at the coldest biome on Earth where the ground stays frozen all year.
Imagine a place where the ground is a giant popsicle that never melts, and trees are shorter than your sneakers. How do animals survive in a world that stays frozen almost all year round?
The Tundra is the coldest of all the biomes. Its most famous feature is permafrost. This is a thick layer of soil that stays frozen for at least two years in a row. Even when the sun comes out, only the very top layer of dirt thaws. Because the ground is like a solid block of ice just a few inches down, deep roots cannot grow. This is why the Tundra is a treeless plain; there simply isn't enough room for a tree's roots to anchor themselves or find liquid water underground. Temperatures here can drop to in the winter!
Think of the Tundra soil like a layer of chocolate cake sitting on a block of concrete. 1. The 'cake' is the top to inches of soil that thaws in summer. 2. The 'concrete' is the permafrost that never melts. 3. A tree needs roots that go to feet deep to stand up. Since it hits the 'concrete' almost immediately, the tree would fall over in the wind!
Quick Check
What is the name of the soil layer that stays frozen all year and prevents trees from growing?
Answer
Permafrost
Animals in the Tundra have developed amazing adaptations to survive. Many have thick layers of fat or blubber and heavy coats of fur to trap heat. Some animals, like the Arctic Ground Squirrel, use hibernation. They go into a deep sleep during the coldest months to save energy. Others change their appearance; the Arctic Fox grows a white coat in winter to blend into the snow and a brown coat in summer to hide among the rocks. This is called camouflage.
Let's look at how two different animals handle the cold: 1. The Musk Ox: It has two layers of fur. The outer layer is long and shaggy to shed rain and snow, while the inner layer is soft wool to keep heat in. 2. The Polar Bear: It has black skin under its white fur to soak up the sun's rays, and a -inch layer of fat to stay warm even while swimming in ice water.
Quick Check
Why would an Arctic Fox change its fur color from white to brown?
Answer
To use camouflage to hide in different seasons (snow in winter, rocks/dirt in summer).
The Tundra summer is very short, lasting only about to weeks. During this time, the sun shines almost hours a day! Plants must grow, bloom, and make seeds incredibly fast. Because of the high winds and cold, Tundra plants like mosses, lichens, and low shrubs grow very close to the ground. This keeps them out of the freezing wind and allows them to soak up the heat reflecting off the dark soil.
Imagine you are a plant in the Tundra. 1. If you grow feet tall, the mph freezing winds will break your stem. 2. If you grow inches tall and huddle in a 'cushion' shape with other plants, you trap warm air between your leaves and stay safe from the wind. This is why Tundra plants look like small rugs on the ground!
Why are there no tall trees in the Tundra?
Which of these is an adaptation for a Tundra animal?
Tundra plants grow tall to reach the sunlight during the short summer.
Review Tomorrow
Tomorrow, try to explain to a friend why you can't plant a giant oak tree in the Arctic Tundra.
Practice Activity
Draw a picture of an Arctic Fox in the winter and in the summer. Use different colors to show how it uses camouflage!