Snakes possess nostrils, similar to many other animals, and these external openings serve a primary function in their respiration. Their sense of smell, however, involves a distinct and more complex mechanism. This unique sensory adaptation allows snakes to navigate their environment, locate prey, and detect potential threats.
Breathing Through Nostrils
Snakes use their nostrils for inhaling and exhaling air. Air enters through the external nares, or nostrils, then travels through the nasal cavity to internal nares in the roof of the mouth. From there, the air proceeds down the trachea and into the lungs. Unlike mammals, snakes lack a diaphragm and rely on muscles between their ribs for breathing.
A specialized structure called the glottis, a small opening behind the tongue, is part of their respiratory system. When not actively swallowing, the glottis forms a vertical slit that opens to allow air into the windpipe. A notable adaptation is their ability to extend the glottis to the side of their mouth during prolonged swallowing of large prey. This allows them to continue breathing even when their mouth is fully occupied, effectively functioning like a snorkel.
A Unique Sense of Smell
While snakes have nostrils for breathing, their primary sense of smell operates through a different system involving their tongue and a specialized organ. A snake’s forked tongue constantly flicks out, collecting tiny chemical particles from the air, water, and ground. The forked shape helps the snake detect the direction of scents, similar to how our two eyes provide depth perception, allowing them to “smell in stereo.”
Upon retracting its tongue, the snake places collected particles onto a pair of sensory organs in the roof of its mouth, known as the vomeronasal organ or Jacobson’s organ. This organ contains sensory neurons that process chemical signals, enabling the snake to interpret “taste-smell” information. Through this system, snakes detect chemical cues like prey, predators, and potential mates, making it a crucial tool for survival.
Other Sensory Structures
Beyond nostrils and the vomeronasal organ, some snakes possess other specialized sensory structures. Certain snake families, including pit vipers, boas, and pythons, have heat-sensing organs known as pit organs. These pits are located on their face, typically between the eye and nostril in pit vipers, or along the lips in boas and pythons.
These pit organs allow snakes to detect infrared radiation, enabling them to “see” the radiant heat emitted by warm-blooded prey. A thin membrane within the pit organ is sensitive to temperature fluctuations, allowing these snakes to accurately strike prey even in complete darkness. This ability is beneficial for hunting at night or in low-light conditions, providing an advantage in locating warm-blooded animals.