Cold Habitats: Arctic and Tundra - Second Grade Science
At the northernmost and southernmost reaches of our planet lie the coldest, windiest environments on Earth: the Arctic, Antarctica, and the vast frozen plains of the Arctic tundra. In these icy habitats, temperatures plunge dozens of degrees below freezing, fierce blizzards howl across barren landscapes, and during the winter months, the sun does not rise above the horizon for weeks at a time. Yet, despite these extreme challenges, magnificent polar bears, emperor penguins, arctic foxes, and hardy mosses call these frozen realms home.
The Polar Regions: The Ends of the Earth
The Arctic and Antarctica are located on opposite ends of the globe and have distinct physical environments.
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| THE ARCTIC VS. ANTARCTICA |
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| THE ARCTIC (North Pole) ANTARCTICA (South Pole) |
| - A frozen ocean surrounded by - A frozen continent covered by|
| land (Alaska, Canada, Russia). miles of glacier ice. |
| - Home to Polar Bears, Walruses, - Home to Emperor Penguins, |
| Arctic Foxes, and Tundra Caribou. Leopard Seals, and Krill. |
| - NO PENGUINS live in the Arctic! - NO POLAR BEARS in Antarctica!|
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The Arctic Tundra: The Treeless Frozen Plain
Just south of the permanent Arctic ice cap lies the tundra biome. The word tundra comes from a Finnish word meaning "treeless plain."
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| THE TUNDRA SOIL: PERMAFROST |
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| Summer: Top few inches thaw into boggy puddles (Mosses & lichens) |
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| PERMAFROST LAYER: Solid frozen rock and ice 1,000 feet deep! |
| Roots CANNOT penetrate frozen soil; tall trees cannot grow here! |
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The Permafrost Barrier
Beneath the thin surface layer of tundra soil lies permafrost—ground that remains frozen solid year-round. Because permafrost blocks tree roots from pushing downward and prevents melted snow from draining away, the summer tundra becomes a soggy plain covered in low-growing mosses, lichens, and miniature shrubs.
Animal Adaptations for Surviving Bitter Cold
Animals living in polar regions have evolved remarkable physical features to stay warm and conserve energy in sub-zero weather.
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| POLAR WARMTH ADAPTATIONS |
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| BLUBBER DENSE DUAL FUR SEASONAL CAMOUFLAGE |
| Thick blanket of Hollow guard hairs Brown fur in summer; |
| fat underneath skin trap warm body air; pure white fur in |
| blocks freezing cold! dense underwool base! winter snowdrifts! |
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Blubber: Nature's Insulating Blanket
Marine mammals like seals, walruses, and whales have a layer of fat beneath their skin called blubber, which can be up to 12 inches thick. Blubber acts like a thermal wetsuit, keeping animals toasty warm even when swimming through icy waters filled with floating icebergs.
Dense Fur and Hollow Hairs
The polar bear has two layers of fur: a thick, woolly undercoat next to the skin and long, clear guard hairs on the outside. Each guard hair is hollow and traps pockets of air warmed by body heat. Underneath their fur, polar bears actually have black skin, which absorbs solar heat from the sun!
Seasonal Camouflage: The Arctic Fox and Hare
Animals like the arctic fox, arctic hare, and willow ptarmigan change the color of their coat to match the seasons: Winter: Their fur turns pristine snowy white, camouflaging them against snowdrifts from predators or prey. Summer: As the snow melts, they molt into mottled grayish-brown fur to blend in seamlessly with tundra rocks and moss!
Penguin Teamwork in Antarctica
In Antarctica, male emperor penguins endure the brutal polar winter to protect a single egg balanced on top of their feet under a warm feathery brood pouch.
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| EMPEROR PENGUIN HUDDLE |
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| ( P ) ( P ) ( P ) ( P ) ( P ) ( P ) ( P ) |
| ( P ) ( P ) [ TOASTY CENTER ] ( P ) ( P ) |
| ( P ) ( P ) ( P ) ( P ) ( P ) ( P ) ( P ) |
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| Thousands of penguins pack tightly together to block howling wind. |
| They take turns cycling from the freezing outside to the warm inside!|
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The Power of the Giant Huddle
To survive howling 100-mile-per-hour winds and temperatures dipping below -50°C, thousands of male emperor penguins pack into tight huddles. The temperature inside the center of the huddle can reach a comfortable 37°C (98°F). The penguins continuously rotate: those on the freezing outer edge shuffle slowly toward the warm center, sharing the warmth so no single penguin freezes.
Chapter Review Exercises
Question 1: What is permafrost in the Arctic tundra, and why does it prevent tall trees from growing there?
Question 2: Name two major geographic differences between the Arctic region and Antarctica.
Question 3: How does the seasonal fur change of the arctic fox help it survive in both winter and summer?
Question 4: Describe how emperor penguins work together as a group to survive bitter Antarctic blizzards.
Solutions and Explanations
Solution 1: Permafrost is a thick layer of soil beneath the surface that stays frozen solid year-round. It prevents tall trees from growing because tree roots cannot penetrate through the frozen ground, and poor drainage creates boggy surface soils during the short summer thaw.
Solution 2: The Arctic is a frozen ocean surrounded by northern landmasses where polar bears live, while Antarctica is a frozen continent made of land covered by massive ice sheets where penguins live (polar bears and penguins never inhabit the same pole).
Solution 3: In winter, the arctic fox grows thick white fur that provides warm insulation and camouflages it against the white snow. In summer, it sheds this coat for a thinner, grayish-brown coat that matches the rocky, mossy tundra ground.
Solution 4: Emperor penguins form massive huddles of hundreds or thousands of birds. By packing closely together, they trap body heat and block howling polar winds, constantly rotating so outer birds move inward to warm up while inner birds move outward.