The distinctive size and shape of the moose's nose are a godsend for cartoonists. But to biologists this nose is no joke. Hence the investigations undertaken by Andrew B. Clifford and Lawrence M. Witmer (J. Zool. 262, 339–360; 2004), “With a mind on the enigmatic function of the nose of moose”.
The moose, Alces alces, is a member of the deer family, but its nasal apparatus is unlike that of any of its relatives. The apparatus overhangs the mouth, and the nostrils are large and laterally sited, as seen in this picture. The muzzle contains a long and complex nasal cavity, with a highly complicated muscle and cartilage system.
Using a variety of techniques, Clifford and Witmer undertook detailed anatomical studies of heads of moose that had been killed after being hit by vehicles, and of related species. Among the adaptive explanations they look at are that the nasal set-up enhances blood and brain cooling when escaping from predators, or that its mobile or tactile features improve the efficiency of feeding.
The authors' best bet, however, is that the curious design of the moose muzzle centres on the nostrils, and is primarily so that the nostrils can be closed when feeding under water. But, as they say, that conclusion is not watertight, and a further explanation — the ability to derive directional information from smell — remains plausible.