Snakes are fascinating and mysterious creatures that inhabit nearly every corner of the world. One of the most distinctive features of snakes is their forked tongues, which flicker in and out of their mouths. But why do snakes have these unique tongues? What purpose do they serve? In this article, we’ll explore the anatomy and function of snake tongues to understand why they are such an integral part of what makes snakes snakes.
Anatomy of the Snake Tongue
A snake’s tongue is a key sensory organ that allows it to detect chemicals, navigate its environment, and identify prey. Here’s an overview of the anatomy and composition of a typical snake tongue:
Forked Shape
The most noticeable characteristic of a snake’s tongue is its forked or bifid shape. Most snake species have tongues split into two protruding, pointy ends. When the tongue flicks in and out, these two tips allow the snake to collect chemical molecules from a wider area. This provides more sensory information about the snake’s surroundings.
Jacobson’s Organ
Each tip of the forked tongue contains a specialised sensory organ called the Jacobson’s organ, named after the scientist who first described it. This organ is made up of sensory cells that can detect minute chemical particles. When the tongue retracts back into the mouth, it deposits these particles into the Jacobson’s organ. Here, the chemicals are analysed, providing information to the snake about its environment.
Sheaths
The snake tongue is anchored to the bottom of the mouth by a tubular, cartilaginous sheath. This sheath protects the tongue and allows it to move smoothly in and out of the mouth. Soft tissue sheaths at the base of each tongue tip aid in collecting chemical molecules.
Muscles
Intrinsic muscles entirely contained within the tongue allow the snake to flick its tongue in and out with incredible speed and precision. Extrinsic muscles connecting the tongue to the bones of the mouth let the snake retract its tongue back into its mouth. Coordinated contraction of these various muscles is what gives the tongue its characteristic flickering motion.
Saliva
The tongue itself does not have any taste buds. However, after retracting into the mouth, the tongue transfers the chemicals it has collected to the roof of the mouth. Here, sensory cells in the soft tissue detect the stimuli and send signals to the brain. Saliva helps move the molecules to the sensory cells.
Functions of the Snake Tongue
A snake’s intricate tongue provides it with a wealth of information about its surroundings. Here are some of the key functions of the snake tongue:
Sensing Chemical Cues
The main purpose of the tongue is to collect airborne and ground chemicals and transmit these to the Jacobson’s organ. Pheromones, molecules from prey, and environmental odors are just some examples of the types of chemicals a snake can detect with its tongue. These molecules provide key information about the presence and location of predators, prey, and potential mates in the area.
Environmental Navigation
By flicking its tongue, a snake can sense chemical cues that help it navigate its territory and habitat. Trailing prey, finding locations for basking or hiding, and locating mates are all facilitated by chemical signals gathered by the tongue. Some researchers hypothesize snakes may even be able to determine cardinal directions by detecting subtle differences in environmental chemicals.
Identifying Prey or Predators
The tongue allows snakes to home in on prey by following chemical trails left behind. Snakes can also sometimes determine what type of potential prey is nearby based on their scent. Additionally, snakes may use their tongue to detect the pheromones of predators so they can avoid or defend against them.
Courtship and Reproduction
Male snakes use their tongues to follow pheromone trails left by females to know when potential mates are receptive. Their tongues also provide input on the sex, health, and species of the mate. Females may use their tongues to lead males towards them. Tongues help snakes determine if a mate is of the same species and evaluate their suitability.
Social Communication
Chemicals detected by the tongue may provide social information to some species of snakes that live in groups. For example, a snake may identify members of its own family group or determine social hierarchy or relationships. Snakes encountering each other may flick their tongues to gather chemical cues about the other snake’s size, sex, and possibly temperament.
How Does the Snake Tongue Work?
Now that we know the anatomy and purpose of the snake tongue, let’s look at how snakes actually use this organ:
Flicking Motion
Snakes flick their tongue in and out by coordinating the contractions of intrinsic and extrinsic tongue muscles along with mouth and throat muscles. Typically, one full flick cycle lasts about one tenth of a second. Flicking brings the tips of the tongue in contact with the environment, gathering chemical molecules.
Depositing in Jacobson’s Organ
As the tongue retracts into the mouth, the tips deposit the sampled molecules into the Jacobson’s organ through two ducts in the roof of the mouth. Here, receptor cells send signals to the brain providing sensory information.
Chemical Discrimination
By flicking the tongue in different directions, a snake can compare chemicals from multiple areas in its environment. This allows it to sense chemical gradients and discriminates between different types of molecules. The portion of the brain that receives input from the Jacobson’s organ is quite large relative to the entire brain size. This indicates the tongue provides a vast amount of sensory information.
Rate Changes
Typically, snakes flick their tongues many times per minute when they are active. However, the flicking rate changes in response to different stimuli and situations. For example, a snake encountering a predator may cease tongue flicking to avoid detection. In contrast, the flicking rate increases when following a pheromone trail to find prey or mates.
Do All Snakes Have a Forked Tongue?
The vast majority of snakes indeed have a forked tongue. However, there are a few exceptions:
Scolecophidia
This suborder includes blind snakes and thread snakes. They have a much narrower and barely forked tongue, likely because they live underground and don’t rely as much on chemical cues for hunting or navigation.
Tortrix
This genus of boa species has an undivided tongue. Researchers think this may correlate with their burrowing lifestyle.
Eryx
Early in development, sand boas have a forked tongue. But as they grow, the two tips fuse together into a single, club-shaped tongue. Their habitat underground means they don’t need a forked tongue to follow scent trails.
So while a forked tongue is nearly universal in snakes, a few exceptions exist, particularly among species adapted to underground environments. But even these have some form of a flicking tongue to provide sensory information.
Do Other Reptiles Have Forked Tongues?
While a forked tongue is characteristic of snakes, they are not the only reptiles to possess this trait. Several other reptiles also have bifurcated tongues:
- Monitor lizards
- Gila monsters
- Blue-tongued skinks
- Chameleons
The function is essentially the same as in snakes – to collect chemical molecules to provide environmental sensory cues. In monitor lizards, the tongue even deposits chemicals in the vomeronasal organ, an organ analogous to the Jacobson’s organ in snakes.
So while a forked tongue is most pronounced and specialized in snakes, it arose early in reptile evolution and has been retained in many lizard species occupying similar ecological niches. This highlights the essential role tongue-flicking plays in these animals’ biology.
Conclusion
A snake’s forked tongue is an amazing, multifunctional organ allowing snakes to navigate, hunt, avoid danger, find mates, and understand their environment. From its intricate muscles and sensory organs to the way it seamlessly integrates with a snake’s nervous system, the tongue is an engineering marvel. The next time you see a snake stick out its tongue, you’ll understand just how critical this organ is for a snake’s survival. While not all snakes have a forked tongue, the huge majority do, benefiting from enhanced chemical sensing capabilities. The tongue provides a window into the world of a snake like no other organ.