For humans, the concept of smell is a bit intangible. Sure our noses can identify milk
that's gone bad or a batch of cookies fresh from the oven.
The human nose can identify some 1 trillion smells, but it's just not that impressive
compared to many members of the animal kingdom.
Take the elephant, for example, that trunk isn't just for grabbing peanuts, it's sniffer
is so powerful it can smell water from miles away. The trunks are also wildly multifunctional;
as a straw,
a dexterous limb, a vibration sensor, and of course, a trumpet.
Alright, you guys ready?
Which kind of begs the question, what is a nose? This isn't technically a nose.
It's more of a bony horn.
This is a nose, but it's also a voice amplifier and somehow, a feature for attracting mates.
So by definition a nose just has to be a part of a face or facial region that contains nostrils
and the organs of smell.
After that noses vary wildly in both aesthetics and function.
Now I want to talk about a nose that is not only highly sensitive, but also has the impressive
ability to remember smells over long periods of time.
They also might be the cutest... I'm talking about dogs.
This is my dog Henry.
I think he's a chihuahua toy fox terrier mix, but he loves treats.
There you go.
But when I hold this treat up for him, Henry's not just smelling like
"yep, that's a treat."
He's smelling in layers, so Henry's smelling the wheat flour, the chicken, the yeast that
make up this treat, all separately.
This is why dogs can detect illegally smuggled items buried in luggage and can even find
people buried in avalanches.
So how does this work.
Well, it all comes down to the structure of the nose and the sensory abilities of the
brain, when Henry inhales his nostrils pull in air packed with molecules that contain smells.
A fold of tissue just inside his nostrils separates the airflow into two paths, one
for olfaction or smells, and the other one for respiration.
This prevents the dog from immediately breathing out to smell like we do.
When they do exhale air exits through different slits in the sides of their nose.
This helps pull new odors into the nose through the nostrils and allows the dog to sniff practically
continuously.
It also helps the dogs can identify which nostrils smell came through, so that they
can locate which direction the smell is coming from.
Pretty helpful for early dogs that needed
to hunt prey in the wild, or in Henry's case, finding the treats I've been hiding around the
house.
After inhalation and separation from the air going to the lungs, a small amount of air
passes over turbinates.
Turbinates are these plates of bony structures that contain scent-detecting cells.
There's even a separate section called the vomeronasal organ, which is used primarily
for social interactions.
So, mostly for sniffing butts.
Dog noses are thought to contain roughly 40 times the number
of smell receptors that humans have.
More if you're looking at a highly sensitive dog like a bloodhound.
All dogs have talented sniffers, but it's a spectrum, some breeds are definitely
better than others.
Bloodhounds actually have more scent receptors than most dogs.
They also have other features that make them the famous nose-with-a-dog-attached.
In fact, those skin rolls that make bloodhounds so unique, actually help them trap and collect
scent particles.
From here, the detected smells are converted into nerve impulses and sent
to the olfactory bulb in the brain.
Within the olfactory bulb, an odor image is created,
combining all the individual smells into a cohesive identifiable one.
This is what helps dogs retain memories of scents for very long periods of time.
There's another characteristic of a dog's nose that makes it unique; the wet and coldness of it.
This is called a rhinarium, and it's that furless skin at the end of a nose.
Now scientists aren't exactly sure what function is serves.
Recent research suggests that it serves as a thermal radiation detector helping dogs
sense heat.
It could also just help scent molecules stick to the nose.
I just want to eat you up.
What do you think of that?
As a vet I often get asked if a dry nose is a sign of illness.
I tell them it can vary from species to species and just because your dog's nose is dry at
that time it doesn't necessarily mean that something we need to be concerned about.
These highly sensitive noses combined with their ability to be highly trained makes dogs exceptional
companions for jobs that require an acute sense of smell.
I spent time with some of the best working with the Wildlife College and the Ivan Carter
Wildlife Conservation Alliance in South Africa.
They use bloodhounds trained at a very young
age to track poachers in national parks and there's even a dog that tracks orphan baby
rhinos, so these guys can be rescued and protected.
Without these dogs we would catch poachers 4 to 6% of the time, implementing these
dogs where they're finding poachers 75 to 80% of the time, and they often catch them before
rhinos been killed.
Thanks to their incredible noses, we've been able to protect hundreds of animals from poachers
and rescue several baby orphan rhinos too.
Thanks for watching our new series Tusks to Tails.
I'm Dr. Evan Antin, with my dog Henry, and if there's an animal you would like us to
feature, please leave it in the comments.
We'll see you next time.