Berlin - Baby polar bear Knut captured the public's imagination at the Berlin Zoo, arousing controversy over the merits of people raising animals rejected by their mothers. He was brought up by zoo keepers and was the first polar bear to survive past infancy at the zoo for more than 30 years.
Now Knut, who died unexpectedly at only four years old in March 2011, has been re-created at the Museum für Naturkunde Berlin (the natural history museum), another rather contentious move.
Staff at the museum first made a clay model of his body, faithfully copying it using bones and photos. After casting in plaster, staff then made a replica in rigid PU foam, before the bear's skin and head were applied.
This new Knut, testimony to the expertise of taxidermists, is in a display called "The Value of Nature" until 15 March, which looks at his extraordinary popularity, as well as his role as ambassador for an endangered species.
"We know this animal has great symbolic power. It stands for the protection of an endangered species and for the fight against global climate change and also for the relationship between man and animal," explained museum director general Johannes Vogel, in a press statement.
Vogel added: "We are aware that public opinion is divided on the decision to have the polar bear mounted, and we do respect other points of view, but we simply cannot please everybody."
Step by step taxidermy
The Berlin Museum's website has details of how the Knut exhibit was created, first by layering clay onto the original skull to make a separate detailed model of the head. Staff used the death mask, several photos and the fur of the head for reference.
Then, the experts built a sturdy anatomically accurate clay reproduction of the skeleton in the given posture, and applied modelling clay applied to rebuild the body muscle by muscle, with a polar' bear's typical fat layer added later.
Because clay is heavy, staff then cast the whole model in a lightweight durable resilient material, rigid polyurethane foam. First they made a multi-part negative plaster cast of the soft clay sculpture, in various pieces, then put these together to form a single mould. The mould was filled with PU foam, gives accurate reproduction of the original clay model, weighing roughly 30 kg.
Finally staff mounted the head onto the body, covered the whole with special glue, and placed the skin carefully in position. Here, the museum noted, special care is needed with the head, because facial expression is so crucial. The whole animal is dried for ten days, with staff continually adjusting the skin and combing the fur to make it as 'life-like' as possible.
