Nature’s finest scent trackers owe their incredible sense of smell to the abundance of olfactory receptors in their noses –or trunks, in the case of elephants. Polar bears, for example, have enough receptors packed into their noses to smell prey from over 32km away (almost 20 miles).
Some dog breeds, like bloodhounds, have up to 300 million receptors (humans have around 6 million). On a good day, dogs can detect food that’s 20km (12 miles) away. Additionally, the structure of most dogs’ noses, with large amounts of nasal tissue and a high surface area for sensing smell, is designed for scent detection, especially when it comes to finding food.