Knut with zookeeper

(Image credit: © Markwaters | Dreamstime.com)Polar bear Knut with his zookeeper Thomas Doerflein (who had died in 2008) on the day of the first public appearance of the little bear in March 2007.

Knut's Debut

(Image credit: © Markwaters | Dreamstime.com)Knut made his first pubilc appearance at the Berlin Zoo in March 2007. He was born in captivity on Dec. 5, 2006.

Baby Needs

(Image credit: © Markwaters | Dreamstime.com)Zookeeper Thomas Doerflein cared around the clock for Knut at birth, reportedly sleeping on a mattress next to the tiny fluffball. For the first few months, he was feeding Knut every two hours with a bottle of baby formula mixed with cod liver oil.

Fluff-ball Knut

(Image credit: © Markwaters | Dreamstime.com)Knut weighed just 1.8 pounds (810 grams) at birth, but by age 2 he weighed some 440 pounds (200 kilograms). Here Knut is just a few months old.

Knut at the zoo

(Image credit: © Markwaters | Dreamstime.com)Even though Knut's fur looks white, his hair is really made of clear, hollow tubes filled with air.

Getting older

(Image credit: Berlin Zoo)The Berlin Zoo's beloved polar Bear Knut, whose antics and cute demeanor charmed the world, died unexpectedly over the weekend, on March 19.

Knut at the zoo

(Image credit: Berlin Zoo)Knut at the Berlin Zoo.

Knut

(Image credit: Steven Seet)Here, polar bear Knut at the Leibniz Institute for Zoo and Wildlife Research Berlin (IZW).