Anyone who’s seen snakes knows they frequently flick their tongues out of their mouths, even if just for a few brief seconds. But why do they do it? Do snakes smell with their tongues? The answers may surprise you.
The history of ideas
When you think of your typical tongue and its purposes, you might list eating or talking. Some animals use their tongues to catch prey or clean themselves. Can the same be said of a snake’s tongue? And why is it forked?
The tongue flicks of a snake are unique to that animal. People have long wondered what purpose a snake’s tongue flick serves. Aristotle was fascinated by snakes and pondered the reason for tongue flicks; he hypothesized that it served as a taste organ. In the 17th century, a widely held belief was that, like other reptiles such as chameleons, snakes caught insects with their tongues. This was never observed, however. Italian astronomer Giovanni Hodierna thought snake tongues were used to clean dirt out of their nostrils. A long-held myth is that the snake tongue is the source of snake venom. This idea was perpetuated in various Shakespearean works. But autopsies of snakes performed since the Renaissance have disproved that theory, too.
A sixth sense … sort of
Snakes actually have no way to process smells or tastes through their tongues. They do use their tongue for one of their senses, though. It is a sense that humans don’t have and that is the detection of various chemicals. Although humans can’t detect these compounds, known as pheromones, they are common to many animals, including cats and dogs. It’s not just the tongue that creates the sense — it is an organ in the snake’s mouth called Jacobson’s Organ. Since the 1800s, scientists have known that the snake tongue is used to help snakes gain an understanding of their surroundings. Indeed, snakes use their tongues to pick up hints of pheromones on the ground or in the air.
There are two different types of tongue flicks, one for retrieving particles from the air and the other from the ground. These pheromone particles are deposited in the mouth from the tongue and then taken by the two-lobed Jacobson’s Organ. Next, they are processed as electrical sensations and sent to the brain. The Jacobson’s Organ, also known as the vomeronasal organ, is also found in other reptiles. The length of the tongue allows a snake to detect particles in 100 times more air than the simple downward extension of the tongue would permit. The act of flicking the tongue stirs up the air, creating vortices that hover around the snake’s tongue letting them inspect more air for pheromones.
A fork for a reason
Now we know why a snake flicks their tongue so often — to decode details about their environment. However, that doesn’t answer the question of why a snake’s tongue is forked. It is relevant, though. The forked tongue allows a snake to gather information from two places simultaneously. It allows snakes to create a sort of chemical gradient, so that they can navigate the world around them using pheromones. The reasoning behind a snake’s forked tongue was proven in the 1930s by a German scientist named Herman Kahmann, who observed that snakes who had the forked portion of their tongue removed were much less able to follow trails.
More recent studies have shown that pheromones tracked are not just those of potential prey, but also those of potential mates. In fact, male snakes generally have longer, more deeply forked tongues than females. This is so males can pursue potential female partners, which is the normal method of snake courtship. Snakes follow trails by detecting the trail with each fork of their tongue, and adjusting the direction in which their body is moving accordingly. For example, if one fork does not fall within the trail, the snake will move in the opposite direction.
Now you know probably more than you wanted to about a snake’s long, forked tongue and why it flicks. Use this knowledge to impress a curious snake fan, or let the facts be a simple introduction to the world of herpetology — the study of reptiles.
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