Knut, the world's most famous polar bear, dies

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It's a sad day for polar bears: Knut, the world's most famous polar bear, died Saturday, Mar. 19, in Berlin. 600 Berlin Zoo visitors were horrified when Knut suddenly collapsed, then floated dead in the water, People Pets reports.

The Berlin Zoo bear keeper Heiner Kls says, "He was by himself in his compound, he was in the water, and then he was dead." An autopsy will be performed on the 4-year-old to determine the cause of death. Polar bears in captivity have been known to live for at least 30 years.

"This is sad news," Berlin Mayor Klaus Wowereit tells the tabloid B.Z. "We  were all so fond of him."

Knut was born Dec. 5, 2006, and his mother, Tosca, rejected Knut and his twin; his sibling died four days later. The polar bear was then cared for by Thomas Drflein, who hand-raised him. When Drflein died in 2008, a custody battle ensued with the Berlin zoo eventually winning (for $600,000).

Knut has inspired a line of toys, puzzles, posters and T-shirts and participated in a Vanity Fair cover shoot with Leonardo DiCaprio.
Photo/Video credit: Getty Images