cubs Twin polar bear cubs born last month at Munich's Hellabrun Zoo were filmed opening their eyes for their first time. Photo: YouTube

A video showing two polar bear cubs opening their eyes for the first time that was filmed last month has been shared online by Munich’s Hellabrun Zoo.

The polar bear cubs weighed 14-ounces when they were born in December. The twin cubs were considered to be in critical condition during their first few weeks of life, during which time the average cub's mortality rate is around 70 percent. Now, at five weeks old, their gender has yet to be determined.

“At the moment they’re starting to explore their home -- two litter boxes and a play area in the polar bear maternity den -- not yet on foot, but with their eyes,” the zoo said in a statement. “This is the latest development for Mum Giovanna’s cubs -- they’re both opening their beady, black eyes and taking in their surroundings bit by bit.”

The video shows how their mother’s warm breath entices them to open their eyes.

“It really is a joy to be able to follow our polar bear twins’ development on video," Beatrix Köhler, curator and biologist, said in a statement. "Their mother, Giovanna, continues to behave in an exemplary fashion. Day by day the little ones are becoming more active, bigger and stronger, which is proof that everything is going according to plan.”

This is the first video of the twin cubs since their birth and delivery was filmed on Dec. 9. At the time, experts feared that the first-time mother would be overwhelmed and the cubs would not survive.

"We closely monitored whether she warmed the two cubs adequately, had enough milk and whether the little ones found the feeding source immediately," Koehler told NBC News. "All of them did very well."

Zoo officials have yet to examine the newborn pair. When they do, names will be given to the cute cubs.

"We cannot enter the compound because the three cannot be disturbed, so veterinarians will not be able to examine the two before they go outside for the first time, most likely in March," zoo spokeswoman Christiane Reiss said.