human
What is the most important thing I should know about the hippopotamus?
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The hippopotamus is a large, semi-aquatic mammal that can reach lengths of up to 6.5 meters and weights of up to 2,000 kilograms. It has a long, thick, and powerful body with a short tail and webbed feet for swimming. Its skin is tough and waterproof, which helps it to stay submerged in water for long periods of time.