Berlin Zoo does little to prepare visitors for the shock of a first encounter with Knut, the world's most famous polar bear. Placards advertising the ursine celebrity at its entrance gate show a cuddly, snowy-white creature not much bigger than a domestic cat.
A kiosk next door is stuffed full of Knuts. The souvenir toy bears are still cat sized, fluffy and white but this time at €15 apiece they are synthetic, machine washable and have grins on their faces.
A good hundred yards inside, past the pelican pond and the African warthogs, an almost permanent 200- strong crowd of children and camera-waving adults braving a January afternoon, belie the near divine presence of the real Knut - the bear turned future Hollywood film star who has a following of millions.
Knut close up is disconcerting to say the least: he is not white but mired a filthy brownish grey colour by the mud and dirty pools of water in his enclosure. At a year old, and weighing more than 17 stone he is bigger than a man when standing on his hind legs.
On a wet day last week Knut stood alone in his enclosure playing to his gallery of adoring visitors like an accomplished Rada graduate. Somebody had thrown him a six-inch-long plastic toy. Knut rolled it around in his mouth, threw it into a pool and dived after it, snatched it up with his paw and then rose up on to his hind legs before quickly flipping the object back into his mouth again. He did this for half an hour and his audience roared with approval. It was more circus than zoo.
The Knut phenomenon is currently causing a major debate about the rights of caged animals in Germany. The debatewill come into even sharper focus in a few weeks' time when another polar bear cub, this time a female called Flocke will go on show in Nuremberg zoo in what promises to be a repetition of the Knut treatment .
While some insist that bears born in zoos have a right to human intervention to save and secure their lives, others such as the German animal rights activist, Frank Albrecht argue that they become so dependent on man that they end up divorced from nature and turn into hyperactive, disturbed freaks.
"Knut is a problem bear who has become addicted to human beings," he said.
The German zoologist Peter Arras has described Knut as a "psychopath".
The debate has grown following the birth of three polar bear cubs at Nuremberg Zoo to two different female bears. A team of highly experienced zoologists initially argued that nature must be allowed to take its course. They allowed one of the females, which had rejected its two cubs, to kill and eat her offspring because they were too weak to survive.
But the zoo's "bear infanticide" policy coincided with television pictures designed to melt the heart of anybody who cannot help assuming that polar bears are just like human beings. They showed the zoo's other female polar bear, Vera, carrying her female cub, called Flocke or Snowflake, by the scruff of its neck through her enclosure.
Within hours of the images being broadcast, Nuremberg Zoo had performed a complete policy U-turn: a keeper was sent into Vera's enclosure and Flocke was removed "for its own safety". Amid growing fears that the last remaining cub might also be eaten the zoo promptly announced that the cub would be fed from a bottle.
"I don't think anyone could have stood it, if we had allowed our last bear cub to be eaten by its mum," said Nuremberg's deputy mayor.
Without Knut, it is unlikely that the events at Nuremberg would have taken the course that they have. He was also rejected by his mother, a disturbed circus bear called Tosca, and like the Nuremberg bear, faced the prospect of being eaten.
Enter Thomas Dörflein. Within days Knut was placed in the 44-year-old Berlin zookeeper's care. Mr Dörflein instantly fulfilled the role of Knut's surrogate mother, hand-feeding his charge day and night.
When Knut first appeared in public in March last year, there were more than 500 journalists present. The Knut marketing machine shifted into top gear. The first 2,400 Knut stuffed toys produced by the zoo sold out in four days. Within a matter of weeks Knut was sharing the front cover of Vanity Fair magazine with Leonardo DiCaprio. There are games, posters, T-shirts, pop songs, a children's book and silver coins bearing Knut images and the Hollywood producer Ash R Shah, is planning a $3.5m animated film featuring Knut.
For politicians and the environmentalists Knut proved irresistible. Greenpeace was one of the first to feature the cub on a poster for its campaign against global warming.
Sigmar Gabriel, Germany's Environment Minister, has adopted the bear, claiming him as a symbol of the world's endangered species. Yet evidence suggests that polar bears are not facing extinction, even if the ice caps are melting. Alaska. home to a fifth of the world's 25,000 polar bears, currently has its largest bear population in 40 years.
Meanwhile, Knut faces an uncertain and lonely future. The German media like to think Flocke holds the key to his salvation and that she will eventually become his mate. But for most zoologists the idea is pure fantasy. "Knut won't manage anything with a female bear, I guarantee that," insisted Dr Arras.