9781422279229

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Polar Bears

Even as humans encroach more and more into their habitat, polar bears still have room to roam—and swim—for now.

longer, reaching 6 inches (15 cm), and the air inside provides insulation and buoyancy for long swims across the water. Underneath the skin is a layer of blubber, or fat, that’s 2–6 inches (5–15 cm) thick, providing even more warmth and buoyancy.