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Q: What accounts for the color variations in snakes' tongues?
Posted By:

bwaffa

A little something to ponder...

What accounts for the color variations in snakes' tongues?  I've seen black tongues, plum tongues, purple tongues, pink tongues, red tongues, neon red tongues -- one of my WLPs even has a black tongue with white tipping at the fork!  Typically any color in an animal is due to "pigments," sort of a generic catch-all explanation.  Can anyone explain, on a more detailed anatomical/physiological level what's responsible for the variety of colors and how it occurs?  From an evolutionary standpoint, what selective pressures would have acted on tongue color?  Does it affect function at all?

I realize these likely one some those "well, no one really knows..." types of questions, but if no one can answer definitively, I'd still be interested in people's well-reasoned speculations.

Points: 100
Topics: Mouth
Tags: Anatomy, Physiology
Administrative: Show/Hide

Member Comment 10/5/2008 7:49:07 PM

Sparkle
Good question!  Add "Navy Blue" to the list, both my IJCP's have navy blue tongues... 
 
Member Comment 10/5/2008 8:05:18 PM

Kaiyudsai
Interesting topic...... I always wonder the reasons for all of the color variation patterns etc.....I mean there has to be a reason or advantage..... snake patterning really gets me the most....sometimes it's obviously camoflage....but some snake have such bright coloration.....there has to be some reason these things developed like that........ All the retics I've had have pink tongues and pink mouths...the boas black tongues and white mouths...anaconda white and black mouths and black tongues... I know BCC's have deep red tail coloring because they have a tail luring behaviour....Since birds and primates are known to associate red coloration with food(fruit and tender young chutes ) I guess that is a good example of coloration having a use
 
Member Comment 10/6/2008 4:45:43 PM

Riain

Well, why is the human tounge red/pink?
I think most things evolutionary have some purpose, but i also think some things, could just be, well because they do...

Though in snakes with caudal luring, I would assume a dark tounge would be better suited then a light tounge, like the redtail boa using its red tail to attratct a bird, Wouldn't really want the bird to also see a bright red tounge coming out of the snakes head hidden nearby...

Wonder if any snakes use there tounge as a lure?
though i'd imagine the larger boids, retics, anacondas, burms, tounge color would't really matter asmuch.

 
Accepted Answer 10/16/2008 3:08:10 AM

amarilrose
I can tell you this is a complicated question! 

Yes, at the biological level, color is determined by pigment - and the many different colors are the effect of many different combinations of pigments, or lack of pigments... but I doubt this topic has been explored much at all, so I can reason by analogy about the rest, but it IS hypothetical.

A better question (for research) might be "is there evidence of selection pressure on tongue pigmentation?"  Personally, I would say probably not.  While some species' tongues are quite brightly colored and others' are rather drab and dull, I think the color of the tongue would have more to do with the general pigmentation of the surrounding tissues (like how well does it match the external color of the animal, or the color of the inside of the mouth?), or even random chance because by the time a snake is close enough to a prey animal that its tongue can be seen, I think it's mostly all over for the prey. :)  What I mean by this is that I don't really see a reason to think that tongue color had any direct role in selection.  Anyone is free to disagree.

An interesting finding in research that could be applied here is  from a 40-year Russian study known as The Farm Fox Experiment. {I don't know how to post active links yet, so I'll try, but you can always copy & paste if I don't get it right}     http://www.floridalupine.org/publications/PDF/trut-fox-study.pdf      The study I am referring to involved a systematic selection process for behavior, and ended up creating a wide range of physical changes, including changes in pigmentation.  I am NOT suggesting that any of these differences in snake tongue pigmentation are due to humans meddling in our reptiles' selection.  What I find applicable here though, is that the physiological development of the location of pigment in the skin & other areas is determined in fairly early fetal development, and has been shown through this experiment to be affected by the changes caused by selection forces on what would appear to be completely unrelated traits.  Who would think that selecting foxes for behavior traits over several generations would cause such a wide range of physical changes? 

I first read about The Farm Fox Experiment in a "Physiology of Behavior" course I took that went far more in depth into the workings of the nervous system than you would probably ever care to know - and reading this study may have been the most "behavior" that was actually covered!  One of the things we discussed in that course was that the experiment accidentally discovered that these changes in pigmentation (piebald pattern for the foxes) was specifically caused by the physiological changes that were being selected for as a result of the scientists' selecting for behavior traits - that in selecting for a change in behavior, the foxes were effectively being selected for changes in their neurological (brain) development, which also happened to impact the timing of pigment cells' "migration" in the fetus's developing skin, with the end result being a change in pigmentation pattern in addition to the actual behavior trait that had been intentionally selected.

Where this may apply to snakes' tongues is that snakes have of course evolved with many selection forces, and some of them had to have been behavioral (and therefore neurological).  Why else would arboreal snake species tend to have such different temperaments than more terrestrial ground-dwelling snake species?  That's just one example, but I think you get what I mean. (?)  Anyhow, some of the selection forces that have created the snakes we are familiar with today may have indirectly caused changes in stages of fetal development which in turn resulted in the wide array of tongue colors between species.

I try to write as much in plain English as I can.  If I have slipped too far into "scientist speak," then holler at me & tell me what doesn't make sense I can try to explain differently. :)
I realize this isn't exactly an answer to your question, but I thought this was more informative than "I don't know, and I don't really think anyone else knows either."  ;)  Asking questions makes us want to learn more - no harm in that!

~Rebecca
 
Member Comment 10/22/2008 8:00:05 PM

Mongrel Kitty
Photos of some of my snakey tongues here!:

http://www.iherp.com/Public/Blog/Detail.aspx?uid=3016
 
Member Comment 1/12/2009 10:39:43 AM

amarilrose
Since the ATB's have really turned my head lately, I was looking up a lot of the sources that were recommended when Tea posted her question about them.  One link is very informative, even though the page is a little rough: http://www.amazontreeboa.org/treeboa.html

At the bottom of the webpage, there is a list of references, one of which sound like it might be of great use in this question, as it sounds like it comes from a population genetics standpoint:
Henderson, Robert W. 2004. Correlation among Dorsal Body, Iris, and Tongue Color in a Local Population of Treeboas (Corallus grenadensis) on Grenada, Lesser Antilles. Caribbean Journal of Science 40(2) 270-273
 
Author Comment 1/21/2009 12:21:42 PM

bwaffa
Sweet, Rebecca!  That looks like just the kind of study we're looking for.  The article is on order!  I'll share what I learn here.
 
Member Comment 9/30/2009 2:58:15 AM

amarilrose
follow up??  ;)
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