Have you ever seen a blue-tongue skink flick out its tongue? What exactly is the purpose of that? Is it to smell? Here’s what I found. 

So, are blue-tongues smelling their environment when they flick out their tongue?

The short and sweet answer is this:

Blue-tongues flick out their tongue for two primary reasons; in order to smell around their environment, as well as to catch would-be predators off-guard and scare and deter them from attacking. 

There are actually quite surprising reasons for each of these. Below is a a bit more detail into what I found.

How Blue-Tongues Smell With Their Tongues

You probably know that snakes are able to taste with their tongues, hence why they are constantly seen “flicking” their tongue in and out, in and out.

Blue-tongues also do the same thing, and here’s how it works.

Blue-tongues, like most lizards, don’t have very good taste buds. At least not in the way that we do. Their taste buds can be found in 4 areas:

  • their throat right behind their nose and mouth
  • their tongue
  • right beneath their tongue
  • and on the roof of their mouth

When a blue-tongue flicks out its tongue, what it is doing is swapping up scent particles in the air with its tongue, and then bringing them into its mouth.

Where does a blue-tongue bring its scent-particle soaked tongue when it retracts it back into its mouth?

It brings it to something called the Jacobson’s organ, also known as the “vomeronasal” organ.

All lizards have this special organ, including blue-tongues.

This organ is part of a highly-specialized chemical-sensory system that contains very advanced nerves which can identify and distinguish different smells.

Blueys then use these scents in order to:

  • find prey, such as insects, plant life, vegetation or nearby rotting, dead meat
  • recognize other blue-tongue skinks nearby
  • locate potential mates
  • recognize their nearby environment and possible routes of exploration
  • find and identify areas with potential predators

That’s the gist of it at least.

So, whenever you see your blue-tongue skink flicking out its tongue, what it is doing is smelling everything around it. 

Think of how a dog uses its extraordinary nose to sniff its environment, and how often it uses that ability. The tongue of a blue-tongue skink works very similarly.

However, that’s not the only reason that a bluey flicks out its tongue.

Sometimes, it uses it as a possible last ditch effort…

Why Blue-Tongues Show Their Tongue When Threatened

In the wild, bright, vivid colors almost always signify danger for potential predators.

Use the poison arrow dart frog native to the forests of Central and South America as an example. Their bright, flashy reds, yellows and blues signal to would-be predators “POISON! DON’T EAT ME!”

But what about blue-tongue skinks?

Blue-tongues don’t have any blue on their bodies. In fact, the colors on their bodies are almost always quite tame and drab. The only thing that really sticks out are their bright, fleshy blue-colored tongues.

Is there something similar to the poison arrow dart frog going on here?

That is the exact question some researchers from Macquarie University in Melbourne tried to find out according to a study published in June of 2018.

Lizards, unlike humans and many other animals, are able to see different wavelengths of UV light.

Interestingly enough, the researchers found through testing that the back of a bluey’s tongue is able to reflect about twice as much UV light as the middle and tip.

As I noted above, blueys use their tongue to pick up scent particles of their surrounding environment. And when they do this, they don’t show the back of their tongue, they just use the tip.

Could this be because blueys do not want other animals capable of UV-sight seeing them as they flick out their tongues?

Possibly. But the researchers posited a different theory.

They used a pair of metal prongs to simulate the appearance and attack of different, but common blue-tongue predators, animals such as:

  • bigger, larger snakes
  • foxes
  • kookaburras
  • monitor lizards

They noticed something interesting.

When the simulated animals were more than a meter and a half away, the skinks still didn’t flash the back of their tongue. Only when the metal prongs got way too close, at around 50 centimeters or so, did the blue-tongues immediately stretch their mouths wide open and show the backs of their bright, blue fleshy tongues.

The theory goes like this:

As blue-tongues lack a lot of natural defense mechanisms, such as flight, climbing, sharp teeth or even sharp claws, they must have something else.

The element of surprise.

When a blue-tongue is threatened, it flattens out its body in order to make itself appear bigger, hisses and opens its mouth wide to show its vividly-colored, UV-reflecting tongue in all its glory.

To animals that can see UV light, this catches them off guard and either deters them, or buys the bluey enough time to make an escape.

Or so the theory goes.

Another theory done back in 2015 says something quite differently however.

According to that theory, a bluey’s UV-reflecting tongue isn’t displayed to ward off-potential predators as much as it is to intend to show nearby blue-tongue competitors whose territory this is.

The fact that it can also ward off would-be predators is merely secondary.

One possible reason why this theory may also have some credence is the fact that some common blue-tongue predators, such as birds, cannot see UV light. Moreover, birds of prey typically swoop down from above, unbeknownst to the prey. An animal that used its tongue for the purpose of defense would have virtually no time to actually use it in these circumstances. Moreover, foxes, like many other mammals, also lack the ability to see UV light.

As blue-tongues are highly territorial, and as other lizards do use UV light in order to communicate, the theory goes that this capability developed mainly as something to display to other blue-tongue skinks.

Those are the 2 theories which make the most sense to me at least!

To sum everything up in this article:

  • blue-tongue skinks flick out their tongue in order to smell their environment and find predators, prey and mates
  • according to one theory, blue-tongues also display the back of their tongues to ward off predators by emitting tons of UV light
  • according to another theory, blue-tongues display the back of their tongues primarily to display to potential rivals and for territory purposes

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