Shrew knew! Shrew snouts found to grow bigger in winter

Move over Pinocchio, some shrews don't have to lie to grow a bigger nose.

Scientists were left a little perplexed when looking into how shrews around the world adapt to winter conditions.

Shrews are very small mammals that are closely related to moles and hedgehogs, and are found all over the world.

Researchers have previously discovered that some species of shrew can shrink their bodies and organs in the cold to conserve energy to get through the winter, rather than hibernating like some other mammals.

But scientists have now found that whilst long-clawed shrews - found in Asia - shrink most of their body, their snout actually gets bigger!

During the winter, some small mammals like shrews can dramatically shrink the size of their skulls, brains and organs in a process called Dehnel's phenomenon.

Scientists think this helps them to save their energy when there is little food around and it's very cold.

It's mainly been seen in small mammal species in Europe.

Yugo Ikeda, a mammalogist at Tokyo University in Japan and the lead author in the latest study, wanted to see if it also happened in small mammals, like the long-clawed shrew, in Northeast Asia.

He said his team's findings were "completely unexpected and caught us all off guard in the best way possible".

They measured the skulls of 136 shrews from museum specimens, as measuring them in the wild would be very difficult.

All of the specimens were collected from the Japanese island of Hokkaido between 1948 and 1988 during different seasons.

The researchers compared the skull dimensions with the seasons they were collected in.

They found that during the winter months, the shrews' snouts were 7% taller and 6% wider.

Ikeda is calling it "areverse Dehnel's phenomenon".

The team say the change in snout size is reversible, changing back to a smaller size in summer months.

His team's hypothesis on why this might happen is to help warm up the air so the shrews think more clearly with their smaller winter brain.

"Expanding the nasal cavity creates more room for a rich vascular network," said Ikeda. "When the shrew inhales freezing air, this network efficiently warms it before it reaches the delicate, winter-shrunken brain – helping maintain core cognitive functions."

The bigger nose may also boost shrews' ability to sniff out food, such as earthworms.