Shell color and temperatures...

[ticothetort2]

Never started one of these but just wanted to throw it out there and see what everyone else had to say. This is primarily directed towards leopards but I'm sure could be asked of other species also.

Question:

Do torts in cooler temps have shells that grow darker than those who are in warmer climates. Sort of an adaptation to warm up faster or stay cooler depending on climate.

Haven't done very much research on it, just testing the waters on what everyone else (those of you who have been into this a lot longer than myself) might know or think.

 

[Tom]

Are you talking about changes induced by the captive environment or adaptations in the wild?

 

[ticothetort2]

I guess both...

Having traveled you've seen torts from different regions, do they differ in lighter to darker shells consistently?

In captive torts would say ambient temps of 70 degrees vs. 80 degrees cause torts to grow darker? Could you grow a darker/lighter tort if you wanted to?

Like I said in my first post, I haven't done research on this, just wanted to see what you all thought. I would just assume that it would make sense that a darker shell would trap heat easier than a lighter shell.

Maybe it has nothing to do w/ it at all??

 

[Tortuga_terrestre]

I was talking to another member about this very topic... I would say darker shelled tortoise are more cold tolerant than lighter ones... I would assume they retain heat more.. Example...try wearing a black shirt on a hot day..versus a white one..

 

[Tom]

Well all the ones I saw in SA were very dark. I only saw about a half dozen wild ones, but I saw 100's of captives. All were pretty dark. I don't know if that's from the soil and weather or if its pigment. I've never been to the parts of Africa where the babcocki come from, so I have nothing to compare it to, except pictures on the internet.

In captivity it seems like about a half dozen out of the 36 are doing the "blonde" thing. I have one that is REALLY blonde and a couple others that are just a little lighter. All of mine are housed together in identical conditions.

 

[ticothetort2]

Looks like I'm going to have to start saving for next time you get more GPP Tom, an experiment is a good excuse for more torts...right?

I had thought about dirt and diet as well, I remember one of the members who lives in SA showing off some of her adult leopards. Hers were all kept on a reddish color dirt and they all seemed to have an orange hue to the shells, maybe certain minerals that get consumed. Kind of like flamingos turning pink from their diet...

 

[John]

It makes sense that a darker animal will absorb heat quicker, this would possibly make same animal less tolerant to hotter conditions, I imagine shell coloration and skin pigment play some role in temperature regulation, but I would also think it serves as camoflage.

 

[GBtortoises]

The theory has always been that cooler climate and higher altitude tortoises are darker and warmer climate and lower altitude tortoises are lighter. But within the Gracea (Greek tortoises) complex, this isn't always the case at all. There has been and continues to be examples of very dark Greeks found at lower altitudes and several populations where there are both very dark and very light members of the group.
The ability to regulate body temperature may have had some influence on a tortoises color evolution but it's probably also a combination of everything else including geographic location (soil content, food sources, weather patterns), genetic diversity (or little genetic diversity). But most of all, probably the need to blend in better with their surroundings in order to survive.

 

[Neal]

I've heard it said from a few different sources specifically that leopards will develop a darker pattern if kept in cooler temperatures, and a lighter more blonde pattern if kept in higher temperatures. Unfortunetley those observations are third hand information so I don't know what they are really based on.

Some people I've spoken with that live in South Africa and raise tortoises find it very odd that the "pardalis" we keep here in the states show a lot of blonde. Rarely do they see that color over there in their tortoises. My guess would be that the tortoises they raise are kept much cooler than how we keep them here in the States.

I have plans to experiment to see if shell color can be manipulated by environmental conditions...just need to find the time to set it all up.

---

You can read Danny's response to this similar topic from awhile ago. His is #47.

http://www.tortoiseforum.org/Thread-Black-Leo?page=4&highlight=black+leopard#axzz1LmUOXj4x

 

[coreyc]

Here's some pic's of two of my GPP's both kept in the same enclosure one reminds dark the other is getting lighter will be interesting to see how they turn out . ( she is a lot lighter in person then in the pic )

When I got them

Now

 

[EricIvins]

What I've seen is that Leopards that are kept outside and receive sunlight are more apt to have the dark growth lines, and Leopards kept inside tend to err on the "Blonde" side........

The same thing happens with marbled Cherryhead Redfoots..........

 

[Saloli]

I know that the eastern snapping turtles up in pittsburg are darker the the ones here in middle river and the mexican snappers are lighter than the ones here i'm not sure if it is related to thermalregulation which in the case of the darker ones could lead to a longer active period. or if it related to the camoflage principle (slight genetic variations that allow them to hide better then animals from different areas) for example turtles from areas that have mostly sand would be lighter colored vs ones from a forest stream with peat on the bed. though snappers have some ability to change color of their shells and skin it is limited. i am unaware of any tortoise that can do it though.

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The darker pigments could be a form of u.v. induced melanism (tanning). which would make sense because too much u.v.b can destroy vit. d3 and cause other damage for example to dna

 

[Peacebone]

Well the sun can cause bleaching or color fading. Like raising an Aldabra or Galapagos here in AZ, they are typically lighter in color more of a gray rather than black (you can see examples in Norman's, Gummybearpoop, post with the pics of Galaps and Aldabras at the zoo). Not really in the same lines of blond tortoises but just taking a different view on the question.

 

[Tom]

Well the sun can cause bleaching or color fading. Like raising an Aldabra or Galapagos here in AZ, they are typically lighter in color more of a gray rather than black (you can see examples in Norman's, Gummybearpoop, post with the pics of Galaps and Aldabras at the zoo). Not really in the same lines of blond tortoises but just taking a different view on the question.

That's interesting. I hadn't noticed that. Greg's Aldabras are in the sun from nearly day one and they get all black within the first couple of weeks in the Florida sun. (I know this because he's shown us a few pics.)

As Corey's pics above demonstrate and my torts too, some of them just seems to lighten up while others don't. All of mine are in the sun almost daily and they all share the same enclosure and the same food. Everything is identical. Most of them look "normal" but a few are lighter like the one in Corey's pic.

Interesting what Neal had to say about the South African's. All the ones I saw were very dark too. I wonder where in the range the ones we call Gpp actually came from. THere must be a specific locality in SA where they are sometimes lighter than the norm. I'll ask my breeder if he knows specifically what part of SA they came from.

 

[Baoh]

My previous experiences with Russian, Eastern Hermann's, Leopard, and Redfoot tortoises were that increased heat resulted in blond or lighter new growth. When I noticed tortoises in the same enclosure that had differences in this regard, it was often that one with darker growth would spend more time in cooler parts of the cage and one with lighter growth would spend more time sleeping directly under or very close to heat sources on average. Then there is individuality, population differences, and so on. My darker animals tend to be active at cooler temperatures than my lighter ones. Easier to absorb and perhaps retain heat.

 

[John]

I think comparing captives here has no merit, In a wild tort you could look at climate and the surounding terrain to see what may induce coloration. Animals here in the states most likely have been bred together from different ranges therefore altering thier coloration genetically.As Neal mentioned most sa's in thier home region are mostly dark, makes me wonder, when these animals were still being imported and so little known about them was the gene pool here in the us completely corupted? Do true south africans really exsist here, or are we going with the closest we can find? It makes total sense to me that an animal from a hotter climate ,less vegetation more sandy terrain would be lighter in coloration than one that came from an area with greater vegetation or say maybe a rocky terrain. What we need here are documented examples of torts known to have come from a specific area (adults).what the climate and terrain was like in that area. and then compare them to other documented animals from different areas, I would have to think the fifes are the best chance of having the means to do this, at least with south africans.

 

[Fernando]

I haven't read many of these types of threads so this might have already been done...but has the following experiment already taken place?

Has it already been determined that the darker tortoise heats up faster?

Has someone that has a light tortoise and a dark tortoise of the same type, age, and size placed them in same outdoor enclosure (or indoor) and have measured the temps at the same time? 30 minute or Hour intervals?

I'm sure it would be hard to do because tortoises grow at slightly different rates so that could always be another factor.

I don't have the resources obviously to determine this but I think it would be interesting to find out...especially HOW MUCH FASTER will they reach a certain temp.

 

[Zouave]

IMHO

I think heat determining colour would be an evolutionary change and therefore take many generations, so if you wanted a tort of a certain shade you would be better off breeding for those shades by choosing appropriate parents.

@FernandoM - You would need to take core temperatures to be certain. Surface temp would almost certainly favour the darker.

 

[onarock]

Interesting stuff and thanks for the pics Corey those are great. There are known different haplotypes from the SA region along with both sub.sp. of leopards, so determining what is a gpp would take genetic tests. The more reading I do on this subject the more I am convinced that there should be 5-7 different sub.sp or none at all. The 2 animals that Corey presents could very well both be gpp but from different clades. They could be gpp crossed between 2 or more clades as well. To me the lighter colored one looks like some hybrids that I have seen, but who knows.

As far as lighter color tortoises being more adept to hotter environments and vice versa for darker tortoises, I think a case can be made. I think that the more strikingly marked hatch-ling and juvenile tortoises are better suited to hide than their adult counterparts.

FernandoM. there are people that have studied internal body temps of tortoises (including leopards) in the wild. Dont know if they recorded the rate at which the tortoises heated up but they recorded average internal body temp over a period of a year through a wide fluctuation of seasonal weather, morning, noon and night ... very interesting stuff.

 

[Tortuga_terrestre]

I have always preferred darker tortoise (especially leopards). What temperature would the enclosure have to be to achieve darker colors? without risking the tortoise health. Could you still use a MVB's for UVB/UVA? or would you have to resort to other heat sources?