( CNN ) -- What 's white and black , and has people fawning all over ? Meet Siku , a polar bear cub born in captivity in Denmark . The cute cub is being reared by handlers at the Scandinavian Wildlife Park because his mother is n't producing the milk to feed him . Since his birth last month , Siku has become a Web star . He has his own page on the park 's website and he 's even on Facebook . Park director Frank Vigh-Larsen says he 's stunned by the cub 's rapid transformation into an Internet sensation . Video footage posted on YouTube of Siku bottle-feeding , rolling around and snoozing has been viewed more than 2 million times in six days , he told CNN , and the cub gained thousands of friends on Facebook within the space of a few hours . As of Wednesday , at 36 days old , Siku has just opened his eyes and weighs in at 4.2 kilograms ( 9.2 pounds ) , more than five times his initial weight , his handler said . `` He 's just a little solid cannonball , '' Vigh-Larsen said . `` He 's doing well . '' Such growth is a testament to the dedicated care Siku is receiving . For the first three weeks , Vigh-Larsen fed the cub every two hours -- and still feeds him every three hours , meaning the keeper gets little sleep . In the new year , two other wildlife keepers will start to care for him , too , in shifts , making sure the cub is never alone during the first 12 months of his life . Siku 's popularity comes at a time when concern over the plight of polar bears is at an peak . Corporate giant Coca-Cola recently launched a campaign in conjunction with the World Wildlife Fund to raise awareness about the threat of climate change to polar bears ' Arctic habitat . And Vigh-Larsen is determined Siku -- whose name means `` sea ice '' in Greenlandic , an Eskimo language spoken in Greenland -- will thrive so he can play a role in highlighting the risk . Polar bears rely on sea ice in the Arctic to hunt . `` Siku is going to be an ambassador for polar bears , for global warming , '' he said . Vigh-Larsen draws a contrast with the last polar bear cub to become an Internet star , Germany 's Knut . That bear died suddenly at age 4 last March at Zoo Berlin , to the sorrow of many worldwide who had followed the cub 's progress after he was abandoned by his mother and hand-raised by a zookeeper . The case of Knut was a disaster , Vigh-Larsen said , `` because he was only ever used for selling tickets and teddy bears . '' Siku will have a different mission , he says : using his cuteness to persuade people to listen to warnings about climate change and take steps to protect their planet . It could prove a powerful weapon . The cub has already appeared on front pages of newspapers around the world and graced international TV news bulletins . New pictures will be posted on the Wildlife Park 's website Thursday , Vigh-Larsen said , with the pictures likely to win him even more fans . Vigh-Larsen also hopes that the facilities the huge park can offer will make it possible for Siku to join its four other polar bears -- including Siku 's mother -- as a normal adult male in three or four years ' time , despite being bottle-reared . This is doubly important because of a shortage of polar bears for breeding programs in captivity -- set to become ever more important as the numbers in the wild drop . Scientists believe there could be as few as 25,000 polar bears left in the world , according to Polar Bears International , a conservation group . The animals are only found in five nations : the United States ( Alaska ) , Russia , Norway , Canada and Greenland , the group said . In 2008 , the U.S . Fish and Wildlife Service listed the polar bear as threatened under the Endangered Species Act . Without action , Vigh-Larsen says , research suggests that there could be no polar bears at all in the wild within 40 years . He hopes Siku can help reverse that course .
Siku is being bottle-reared because his mother can not produce enough milk . The baby was born in a zoo and the zookeepers were shocked to see that he had no eyes or nose, but they didn't know what else to do with him Park director Frank Vigh-Larsen wants Siku to highlight the threat to polar bears . Polar bears rely on sea ice to hunt , so are vulnerable to climate change in the Arctic .