When winter comes, humans wear warm clothes to stay warm. But small animals called long-clawed shrews have a special way to survive the cold: their snouts grow bigger in winter.
Scientists in Japan at Toyo University studied 136 long-clawed shrew skulls from Hokkaido. They noticed something surprising. During winter, parts of the shrew's skull and brain shrink to save energy. However, the snout does the opposite—it grows larger. The snout's height increases by 7% and its width increases by 6%.
Researchers call this change the "reverse Dehnel's phenomenon." They believe a bigger snout helps the shrew breathe freezing air. The larger nose cavity warms up the cold air before it reaches the shrew's delicate brain. This helps protect the brain and keeps the animal healthy. A larger snout might also help shrews smell food, such as earthworms, under the snow.
When warmer weather returns in spring, the shrew's body changes back again. Scientists hope to study other shrew species in the future to see if they also change their snouts in winter.