Blue tongues.

[jesswebb93]

I apologise if this topic/question has been brought up before, but I've been curious about it for a while now. Why is it that some subspecies vary in amount of blueness on their tongues? The photos below demonstrate how my Halmahera (top picture) has half a blue tongue, whereas my Irian Jaya has a full blue tongue. I find it rather interesting, does anyone have any idea why that could be?

[alichamp]

My guess would be genetic variation between individual skinks.

[Dakota]

I have found myself wondering the same question. I am actually going to school to be an evolutionary biologist, and this is one thing I plan to study. It really depends on the evolutionary history of how Tiliqua came to be, whether they migrated south into Australia or north into Indonesia — the latter being mostly agreed on (likely because fossil records have been found in eastern Australia), though (unless I'm mistaken) quite the opposite happened for the pythons of Australia. With this being said, we cannot assume they are actually losing color, nor simply their Australia counterparts (and Tiliqua gigas evanescens for the most part) gained it. The lack of a feature usually means they don't need it, so I hypothesize the lowland rainforest dwellers such as Tiliqua gigas gigas may not have found such use of their namesake feature with the help of the dense canopy and vegetation they scurry in. This is purely my hypothesis, and could very easily be proven wrong. A counterargument to my hypothesis would be the fact even some Australian Tiliqua have pink tongues. It has been posted (especially of the Tasmanian lowland T. nigrolutea) showing they also have less blue in some individuals; there has even been a T. occipitalis posted with a completely pink tongue. So, it is hard to give a definite answer, but it is pretty consecutive that Tiliqua gigas gigas have less blue tongues on average than the other species. Whether or not this feature is considered vestigial in relation to Tiliqua gigas ssp., I cannot answer that. Further studies need to be done.

[jesswebb93]

The lack of a feature usually means they don't need it, so I hypothesize the lowland rainforest dwellers such as Tiliqua gigas gigas may not have found such use of their namesake feature with the help of the dense canopy and vegetation they scurry in. This is purely my hypothesis, and could very easily be proven wrong. A counterargument to my hypothesis would be the fact even some Australian Tiliqua have pink tongues. It has been posted (especially of the Tasmanian lowland T. nigrolutea) showing they also have less blue in some individuals; there has even been a T. occipitalis posted with a completely pink tongue. So, it is hard to give a definite answer, but it is pretty consecutive that Tiliqua gigas gigas have less blue tongues on average than the other species. Whether or not this feature is considered vestigial in relation to Tiliqua gigas ssp., I cannot answer that. Further studies need to be done.

Interesting hypothesis, Dakota. Thanks for your input. Hopefully, there'll be studies in the future that answer this question fully. I find it rather interesting that IJ Blueys are from areas of Indonesia and Papua New Guinea and have a similar climate, environment etc as the Halmahera, yet they have full blue tongues unlike the Halmahera.

[Susann]

I thought all the gigas had the half-blue tongues... Certainly all my Meraukes do. What are Kei tongues like?

[Dakota]

My Meraukes have pretty blue tongues.

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I haven't noticed any pink in the Keis, but their tongues seem darker.

[alichamp]

Sorry this topic hasn't really taken off here. I found these old threads that you may find interesting but they don't really answer your question.
Tongue color
What makes a blue tongue skink's tongue blue?

[NickBrahz]

Had a gander at my 3 bubs, 2 Easterns and a Highland/Alpine blotch and they all have full coloured tongues similar to colour as Dakota's Meraukes

[Susann]

My male Merauke Milo (like the alliteration there?):

Milo 4 - Copy.JPG

Merauke Maddie :

IMG_1309-copy.JPG

[alichamp]

According to http://www.bluetongueskinks.net/ one of the listed 'distinguishing marks' for the Indonesian BTS (T. gigas gigas) is:

• Tongue is typically a very light shade of blue which turns pink at about the halfway point

We have seen just on this thread variation between meraukes (T. gigas evanescens) so perhaps it doesn't apply to all gigas (more room for individual variation?).

For anyone who has a copy of the BTS "bible" on hand (Blue-Tongued Skinks: Contributions to Tiliqua and Cyclodomorphus) - is tongue colour described at all?

[Dakota]

What a thought-provoking thread. I like it!

Yes, there is a whole chapter dedicated to it called, "Functionality of the blue tongue in blue-tongued skinks (Tiliqua sp.)".

Here is a phone picture of the page that goes into detail a bit:

KIMG6505.JPG

You may need to click on the attachment to read it.

Anyhow, you can see they were only mentioning hypotheses.

It does mention the lack of blue in Pink-tongued skinks, but they seem to draw the hypothesis that maybe only juvenile need it. Which in part, I agree with — juvenile Hemisphaeriodon likely do not climb as high as the adults, thus requiring the blue tongue only at an early age. Closer to the ground may equate to more immediate predators, requiring the need for a defense mechanism.

Meraukes and Irian Jaya are not found strictly in dense rainforest such as most of the range of T. g. gigas, so this is why I think there is a lot of variation among them. I can honestly say I have yet to see a Halmahera with a full blue tongue. Not saying it is impossible, because I'm sure some are out there.

We need more organismal ecologists and evolutionary biologists studying Tiliqua.

And on another note, I have caught my Halmahera, Maxx, doing a threat display on my phone video camera, and the only color you see is pink.