Snakes have a highly developed sense of smell, but they don’t use their noses to smell. Instead, they “taste the air” with their tongues. They use the damp surface of their tongue to catch scent particles and carry them to a special organ in the mouth called Jacobson’s organ, where they can be identified as food or danger. But X-ray movies have revealed that the tongue does not move inside the closed mouth, it simply deposits the chemicals it has collected onto pads on the floor of the mouth as the mouth is closing.
It is most likely that these pads deliver the sampled molecules to the entrance of the Jacobson’s Organ when the floor of the mouth is elevated to come into contact with the roof following a tongue flick. The case for this is strengthened because geckos, skinks, and other lizards lack deeply-forked tongues but still deliver chemicals to their vomeronasal organs. Bears too have this organ.
Picture Credit : Google