This is the amusing moment a polar bear puts on a mask before diving into a pool.

The ice bear was spotted by zoo-goers playing with a black container in its enclosure in Tokyo, Japan, on April 4.

Footage shows the animal placing the plastic bucket on its head before jumping into the water, eliciting laughter from onlookers entertained by the scene.

Polar bears are listed as 'vulnerable' on the IUCN's Red List of Threatened Species.

Researchers claim these animals face a severe risk of starvation in the wild, as they are forced to spend longer periods on land due to climate change.

Charles Robbins, director of the Washington State University Bear Center, said: 'Our findings show that polar bears cannot survive on land for extended periods. Their specialised diet and hunting behaviours make them highly vulnerable to the effects of climate change.'

With the ice-free period continuing to grow and polar bear populations already in decline, researchers warn that increasing starvation rates could have devastating consequences for the species.

The Centre for Biological Diversity in Arizona stated that two-thirds of the world's polar bears could be extinct by 2050 if greenhouse gas-fueled global warming continues to melt their Arctic sea-ice habitat.