Little roly-poly Knut was an instant international celebrity when he was born in a Berlin zoo four years ago. Five hundred reporters covered his public debut. Millions flocked from around the world to see the adorable polar bear cub in person. Vanity Fair put him on its cover. But fame was cruel to Knut: after being hand-fed by a doting zookeeper and spending his early days playing to cheering crowds, he became "addicted" to human attention. Worse, as he grew, Knut's fans slowly began to melt away--at only five months old, Der Spiegel said it was time to accept the "tragic fact of life" that the cub was "steadily getting less cute." And when he was just over a year old, Knut was misbehaving so much he was declared a "psychopath" by a German zoologist. Knut, another scientist predicted, was doomed to never have a relationship with a female bear.

Knut began acting acting erratically Saturday, The Local reports. Zoo visitors said first the bear's left leg began shaking, then he started walking around in circles. Finally he fell into his pool. Zoo workers pulled his dead body out of the water Saturday afternoon. Knut, whose name meant "cute," was only four years old. Most polar bears live to age 35. The cause of death is still unknown.



Teary-eyed visitors had to explain what happened to their confused kids.

"Knut's short and distressful life shows us again that polar bears do not belong in zoos,"Animal rights activist Frank Albrecht says, "even if they are called Knut."