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[Michaelangelica]

What makes dogs' noses and their sense of smell so powerful?
—Chrissie

Thanks to an impressive network of mucus-coated tubes, Rover's nose is top dog when it comes to sniffing out drugs, explosives, noxious chemicals and even disease.

"All dogs have a great sense of smell, but those with a long snout and big muzzle, like bloodhounds, beagles, labradors and German short-haired pointers are the best," says Geoff O'Neil, a senior quarantine dog handler and trainer at the Australian Quarantine and Inspection Service (AQIS).

What makes dogs' noses so powerful is that they are able to draw in large volumes of air, heat and moisten it, and expose the odour molecules to the sensory cells that make up over 50 per cent of their internal nasal area.

"Those sensory cells then transmit signals to the brain, 10 per cent of which deals only with olfaction — processing and considering smells," says O'Neil.

By comparison, less than one per cent of the human brain is devoted to interpreting smells.

The US Defense Advanced Research Projects Agency, which is trying to develop a more sensitive artificial nose, recently collaborated with Penn State University to make a fluid dynamics model of a dog's nose.

They found that the snout's geometry ensures that a smooth flow of air is delivered to a network of tiny tubes containing millions of receptors that bind to the scent molecules in the air.

The number and variety of receptors allows dogs to detect odours at concentrations as low as a few parts per trillion.

"If you were to spread out the receptor cells of a human nose, they would probably just cover a postage stamp; a dog's by comparison would cover a tea towel," says O'Neil . . .
The number and variety of receptors allows dogs to detect odours at concentrations as low as a few parts per trillion
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Why are dogs such top smellers? › Ask an Expert (ABC Science)