Reptile & Amphibian Forums

I have seen several V.prasinus on reptile shows in Europe, mainly in Germany. But also on pictures on the internet of captive bred animals.

My quesotion is:

Why do most captive bred Varanus prasinus have a blue color, and not the bright dark,yellowish green as the wild ones???

Can anybody help me with that or is it just my imagination?

Thanks

I have noticed this as well, even with long term captives. Could it be the same affliction as the green basilisk/plumed basilisk? In the wild they are a dark, kelly/emerald green, but once in captivity(even captive bred), they appear more of an aqua color. Has anybody ever discovered why this happens in basilisks? Perhaps it has the same to do with the prasinus. I have seen few "green" prasinus in collections; most of the ones i've seen are an aqua/blueish color. However, all of the pictures I've seen of wild specimens show them as being dark green/emerald green. interesting....

bob

The last I heard, the basilisk condition was thought to be the result of lighting and I think I read that if they were kept outdoors in natural sunlight, they would gradually regain the bright green color. I guess you could compare coloration of the prasinus kept indoors vs. outdoors to see if the same thing is going on here. Of course my info. could be way outdated too

I don't know why V.Prasinus does this but I supsect it's a UV lighting issue .

I know that with B.plumifrons it's due to natural lighting . Baptive born baby green basilisk we raised 100% indoors with UVB bulbs had a very slight blueish tint to them . Babies which whose cages we rolled outdoors several times a week were green just like they are in the wild . Both groups were fed exactly the same diet of dusted crickets and King meal worms. I have seen basilisk that were raised 100% indoors without UVB bulbs that were very blue in color .

I also noticed this happening with captive bred Australian White's tree frogs . Tadpoles we raised in full sunlight morphed into green froglets . Tadpoles we raised in natural sunlight but exposed to partial shade morphed into a greenish blue froglets . Tadpoles we raised indoors or outdoors in full shade morphed into froglets that were much bluer in color. All grous being fed the same tropical fish flakes but the more sunlight they recieved the more algae grew in their water which they also fed off of .

Stella St.Pierre
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Stella St.Pierre
www.bluetegu.com

I forgot to add that when we were consitantly breeding Argus monitors years ago (before we did tegus hardcore ) I also noticed a difference in coloration with those raised exposed to UV . Babies exposed to UV lighting had a much richer color to them as subadults /adults (those with no UV exposure looked much more faded in color )

Stella St.Pierre
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Stella St.Pierre
www.bluetegu.com

Green colors in reptiles are generally the result of an interaction between some base pigment and nonpigmented, structural aspects of scale morphology. There are typically carotenoid-based pigments in the skin, yellow or orange in this case, that are derived from the animal's prey. This base color is altered by microstructural details of the scales themselves that reflect blue light, creating a green effect. The carotenoids are maintained metabolically, while the structural elements are properties of (nonliving) keratin. This is why, for example, a dead greensnake quickly assumes a blue color.

It is likely that the aqua shift seen in captive prasinus reflects the absence of the proper carotenoids (or their precursors) in the animals' diets. This is probably mostly cosmetic, in the same way that zoo flamingos moult to white if their diet is not supplemented with red carotenoids.

SS

Sam,
YOu make a good point with the diet thing but I hardly believe that it only that.. But what about the reply on the UV i think that would be a major factor in the colors of most reptiles... Those that have acces to real sunlight or outside light usually look much brighter and healthier?

Has there never been a study on this subject???

I'm sure there have been careful observations, such as those noted above, but I don't personally know of any experimental studies. Maybe some of the zoo-based people do -- Jeff?

Sunlight is not the only thing that varies when you move animals from inside to outdoors -- all sorts of other physiological and hormonal responses are likely to occur from resuming natural light cycles and possibly other cues, and there may be prey in addition to the usual food if insects, small lizards and so on are able to get into the enclosures.

UVB light assists vitamin D synthesis, while carotenoids such as beta-carotene are metabolic precursors of vitamin A. I am not sure that these two vitamins have any interacting effects other than of potentially improving health in general, unless perhaps some of the carotenoids are depositing in the skin instead of melanins in some animals as a "tanning" (protective) response to UV light.
Obviously, this couldn't occur unless the dietary sources of those carotenoids were adequate.

SS

Very interesting point about the carotenoids.
I learn something new everyday and realize that just when I think I have something figured out these animals toss me a loop and make me have to rethink everything I think I have learned.

I grow alot of edible plants & flowers in pots here organically. My favorite colors tend to be warm so I am partial to choosing plants which bear red/orange/yellow fruits or flowers. Many of these including the flowers end up in our animals diets directly or indirectly via our insect bins.

This is especially true in cages which are either kept or rolled outside . It has become a habit to pick a handfull of these edible plants and add them to the cages so that uneaten insects have something to munch on besides the lizards .

Keeping some Cyclura we always have left over hard stems from greens/ veggy peels etc are also tossed in the insect bins (very little vegetable matter here goes to waste and many of these greens / leftovers happen to also be high in carotenoids/luteins? )

Our water here is not processed city water and is naturally high in Iron . If I remember correctly iron aids in the absorption of carotenoids/vitamin A .

Not sure where I read it but I do remember reading a study several years ago on carotenoids helping to prevent sunburns in humans . Makes me wonder if the more exposure these animals have to light in their natural habitats the more use they would have for these carotenoids in their diets .Come to think of it I can not think of one green colored lizard or snake who does not do at least some basking in the sun.

And yes you can not keep any reptile outdoors for any lenght of time and be able to controll their diets 100% ... even with cages designed to keep these critters out since you really don't want to roll the extra visitors back indoors (solid plastic sides and bottoms with insect screen tops - there is always a few insects who don't think its normal to fly horizontal and mange to vertically accend into a cage through wire which is designed to keep them out =P ... a bit of algae growing in a frog pond etc. )

I have to whole heartedly agree on the physiological and hormonal changes that occur in natural sunlight (winter blues in people etc ) ... take a very placid monitor lizard who has been kept indoors for a walk about outside on a sunny day and they seem to suddenly blossom and come to life

I don't think it is so much what prey the insectivor is feeding on that makes such a huge difference but more important what the prey itself is feeding on .

Stella St.Pierre
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Stella St.Pierre
www.bluetegu.com

Hi Sam,
I have suspected something like this carotenoid condition, but do no enough evidence as yet one way or other, just a suspicion that the high green or other pigments of V. prasinus complex is based in-part if not entirely on their regimental catholic diet of walking sticks, katydids, and their kind, along with occassional rodent and even (green) plant matter...it fits your post and why V. prasinus are varying colour in captivity vrs wild populations - in wild green lizard eating green bugs; captivity: light green/light blue prasinus feeding on crickets and rodents (both non green pigment)....a coincidence? I think not. How many other things do these sap-sucking/nectar feeding (= high fructose) insects benefit V. prasinus??

cheers,
markb

Does anyone know if there has been studies done on stomach contents of Varanus prasinus?

And Mark, if you would breed phasmids which ones you must breed or can you feed all of them? I know some are toxic, or that is what i heard? Or can you feed Extatosome sp. or the common walking stick?
Where i live we hard green grasshoppers can they make the lizards green again?

I raise vietnamese walking sticks(Bacculum extradentatum) for my tree monitors. They are very easy to raise, and are ubelievably fast growers. The only problem that I see with these/any stick insects, is that they do not have a whole lot of meat to them, and you must have a messload(i'm talking hundreds/thousands) in order to have a successful breeding colony where you can feed them out, without affecting the colony's production. They also take six to seven months to reproduce, so they are not as prolific as some of the roach species which I also rear. There are other species that are commony raised, including the australian prickly sticks, I believe Mike Stefani raises them for his tree monitors. I also know that Mark knows of a gentleman who is the "phasmid King", who breeds several different species. I believe the gentleman's name is Bob Mackin, you can email me for his telephone number; I've been meaning to call him, but never got around to it.

As for katydids, I have been searching around for people who raise katydids, or any information on where to acquire a bunch of them, and what their captive care/requirments are, but havent' been able to find much.... Going out in the summertime and catching them here is impossible, for them being nocturnal and living atop of trees... I have only come across maybe five or six in my lifetime...they're just not something that you commonly see.

I hope this helps, I briefly describe how I keep my phasmids on my little website, which I'm still working on, but the feeder section is complete, so you can find some more info on how I rear them. Take care,

bob
Link

HI,
I do not breed phasmids, but I do have a telephone no. of a fellow who does in Washington State, and another, Mike Stefani does too for his Varanus...as for toxicity, yes they can direct their ass-spray towards a percieved enemy and it hurts the eyes alot!! There is an article about a guy in 1909 who was sprayed in the eyes and the damage it did to him. I would suspect that the nictating membrane Varanus use also protects their eyes from Phasmid fart-spray.....

cheers,
mbayless

I have caught a number of them here in FL. and I can tell you the spray sucks big time. It burns your eyes and I mean burns them. I washed mine out within 15 minutes of being sprayed. It took me another 15 minutes for the burning to go away and my eyes were then swelled for a time after that.

I now am careful to point the deadly ened away from me. Haha

So as mark said I am sure the monitor has some way around this, as if not they certainly wouldn't be feeling to great after mucking with them. It doesnt have to be a cover over the eyes, as I have learned now from experience to avoid the spray. So if I can learn it I am sure the monitors can also learn this.

It is #1 due to diet, of the animal. Much like alot of other animals. The main one everyone can relate to is the flamingo, change it's diet and it is a white bird and not a pink one.

And #2 would be sunlight, ask any iguana breeder in florida that has animals outdoors. I personaly moved here from IL. where I kept my reptiles indoors. Once down here my iguanas went outside. The have turned out to be the brightest green color I have seen. I also have had basalisks and they do the same.
Seeing how color pigment etc. is pretty similar within reptiles I am sure the same effect would happen on prasinus. Why doesn't someone send me a few so I can test my theory LOL

Well can't blame me for trying now can ya?