Dogs have a lot more nerve cells in their nasal (nose) cavities (their nostrils) than humans do. Dogs also have and a wider variety of receptors that attract odour molecules.

A research team led by Brent Craven of Pennsylvania State University in University Park in 2008 has shown that dogs can sort smells into categories before the information gets to their brains. The brain then identifies the smell.

Before odour molecules can reach smell receptors, they must get through a layer of mucous – the moist tissue inside dogs’ noses. To find out how this might affect smell perception, Craven’s team used images of a dog’s nasal airways to develop computer models of how air travels along them. The team found that different molecules are first picked up at different points in the airway network.

The mucous inside the nose is wet, and the wet outer nose, may also pick up receptors. This may be why dogs are great sniffers and excellent at detecting smells, odours, and scents.

Other mammals may also use their wet noses to pick up the scent of food, temperature, humidity, and other animals.

the nose of a Sika Deer

Photographer: Martina Nicolls

Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM