Essentially it's 'a self-sealing snorkel'

Scientists have spent years pondering the length of the moose’s nose, compared to the far shorter versions seen in other members of the deer family.

In terms of smell, this oversized sense organ could be extra-useful for sniffing out mates or predators. Moose nostrils are spaced widely apart, like human ears, which may allow the animal to ‘triangulate’ scents and better pinpoint the distance and direction of their source.

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It was previously thought that a long nose could also help an individual to shed excess heat when running long-distances to escape wolves. However, dissection research found few blood vessels permeating the nose area, disproving this theory.

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Nevertheless, the dissection did reveal a completely different adaptation. A moose’s nose is flexible, made up of complex musculature and tendons. When an individual is grazing in ponds or sloughs, its nostrils close like valves. Essentially, a moose nose is a self-sealing snorkel. 

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