Animals use their sense of smell to find food, communicate, and get a sense of their external environment and of danger. The olfactory sense, or sense of smell, is an interesting one to study because of how it varies in use and importance when you look beyond the human experience. Different species rely on this sense to a lesser or greater extent, and to some, it plays a significant role in survival. Before looking at some of the species with remarkable olfactory senses, here is a look at how this sense functions.
The sense of smell is part of the chemosensory system, together with the sense of taste. Lining the nasal cavity is a tissue covered in mucus known as the olfactory epithelium. It contains olfactory sensory neurons or receptors which transmit information to the brain.
When air is inhaled through the nostrils, it carries with it chemical compounds known as odorants from everything in the surroundings. This means that all of the scents you detect from your environment are a result of odorants released from the environment that make it all the way to your olfactory epithelium. Once there, they bind to receptors that can detect that kind of molecule. The Shape Theory of Olfaction proposes a connection between the shape, size, and components of a molecular with its smell.
Electrical impulses from the olfactory epithelium are then transmitted to the spherical structures known as glomeruli which are found in the olfactory bulb of the brain. The brain uses this information to interpret different smells.
Who Does It Best?
Some animals have a truly amazing sense of smell. For dogs, as you might have imagined, the sense of smell is highly advanced and plays an important part in the animal’s behavior. It is the animal’s primary sense and is the primary means of communication. With around 300 million olfactory receptors in a dog’s nose compared to around six million in human beings, it’s no wonder its sense of smell is extraordinary. Because of this, canines play a big role in criminal investigations, search and rescue missions, and detecting illegal narcotics.
In terms of the animal with the best sense of smell, while it can be difficult to quantify an animal’s experience, looking at the size of the olfactory lobe and the number of olfactory receptors is a great indication of the strength of the animal’s sense of smell. The bear takes the cup for the best sense of smell among land mammals. They can follow the scent of food or an animal carcass from 20 miles away and can even sense the presence of a seal through very thick layers of ice.
Although the human sense of smell is inferior to that of other animals, it is still simply amazing. Smell is the oldest sense, and in fact, scent cells are regenerated every 30 to 60 days. In a study published in the Journal Science, it was found that humans can detect over a trillion distinct smells. That far superseded previous studies that proposed that only 10,000 different scents were detectable.