That Reptile Blog – Reptile, Amphibian and Exotic Pet Care and Information
Panther chameleons (Furcifer pardalis) carefully regulate exposure to sunlight in accordance with their Vitamin D3 levels, states an article published in the May/June issue of Physiological and Biochemical Zoology.
Nutrient Levels Affect Behavior
Chameleons with high Vitamin D3 levels (achieved through a diet of vitamin-supplemented crickets) limited their exposure to the sun, while those maintained on a vitamin-poor diet maximized basking time. Further analysis showed that, as regarded individual Vitamin D3 levels, the lizards were “…as effective as mathematically possible” in achieving optimal sun exposure. Vitamin D3 receptors in the brain are believed responsible for accessing vitamin needs and controlling basking behavior.
Basking or Diet?
I was most interested in this article because, although this point was not specifically addressed, it established that panther chameleons can be provided with adequate Vitamin D3 (at least in the short term) through dietary means. I have long questioned my observations that certain reptiles, typically thought to be entirely dependent upon UVB radiation (basking) for Vitamin D synthesis, are none-the-less sometimes able to obtain sufficient Vitamin D3 from their diets (please see the article referenced below).
Some Cautions
Information of the type established by this research has a way of taking on a life of its own once spread via the internet, so a few words of caution are in order.
Please bear in mind that the Vitamin D and UVB needs of reptiles vary widely from species to species, and perhaps even within populations of the same species. This research applies to a single species housed outdoors with access to full sunlight, and should not be used as other than a baseline for further experiments as regards other animals.
For now, it remains important to provide the heliothermic (basking) reptiles that you keep with an appropriate UVB bulb (or natural sunlight) and to use vitamin/mineral supplements judiciously. This is a quite important topic, and one fraught with misinformation…please write with questions concerning individual reptiles.
Further Reading
For information on an outstanding UVB bulb and recent tests concerning its output, please see my article on Zoo Med UVB Lamps.
I have written about related experiences with day geckos and red-eared sliders… please see my article Has Anyone Observed This? for further details.
Image referenced from Wikipedia and originally posted by Tom Junek.
Hello Frank,
Very interesting article! (timely too since I’ve been doing a lot of thinking on this)
Is their any evidence whether or not the chameleons know that they are being exposed to UV light?(i.e…if not provided it would they probably try in vain to bask and get D3?)
Their is some confusion with some reptiles needing UV. Generally nocturnal geckos/amphibs are said not to. An interesting one would be pygmy chameleons(specifically Rieppeleon brevicaudatus). Some claim they do fine without, others offer anyway. Many keepers claim they do not bask for them but yet they’ve been observed basking in the wild. I wonder if perhaps when they are supplemented with D3, providing they are happy with their body temp they feel no need to bask?
Thanks again!
~Joseph
Hello Joseph, Frank Indiviglio here. Thanks for the kind words.
I apologize for being so long in responding. The delay was caused by a technical difficulty which has now been resolved.
You raise some excellent points…chameleons do indeed seem to sense their needs for Vitamin D3, and do regulate basking behavior accordingly, but whether or not they sense UVB light itself has not been well investigated. I would hazard a guess that they do, given its importance and the fact that the pineal eye (a sensory organ atop the head of many reptiles) is so finely tuned to light in general. However, in nature UVB is always associated with heat, so temperature may be an important factor. I have noticed that few if any lizards bask under UVB florescent bulbs unless these are paired with heat-emitting bulbs (this is one reason that mercury vapor lamps are so useful), but I have not looked into the question in detail.
The pygmy chameleons are interesting in that many live below dense cover and, much like nocturnal lizards, may have developed the ability to effectively utilize dietary D3. I believe you are correct in saying that they probably do not bask if enough D3 is consumed along with food.
Best regards, Frank Indiviglio.
Also, how wise do you think it would be to have an enclosure by a screen window to get some natural light plus UV(enclosure would need to be screen of course). Placed in a way that the animal could avoid the light if it wanted to. Do you think UV bulbs would still be required in a situation like this?(perhaps on cloudy days or to supplement this light?).
Or perhaps even an aquarium with a side taken out that leads to screen basking area.
Thoughts?
~Joseph
Hello Joseph, Frank Indiviglio here. Nice to hear from you again.
I apologize for being so long in responding. The delay was caused by a technical difficulty which has now been resolved.
Using a screen window to admit natural UVB is a great idea if you can arrange enough exposure while keeping temperatures within safe ranges. Over 30 years ago a wonderfully skilled private reptile keeper in NJ began experimenting with screen enclosures built as extensions onto ground level (basement) and even elevated windows. He was light years ahead of his time, and bred sungazers and other lizards that are problematical in zoos even today. His lizards could even be seen basking “outdoors” on warm winter days – a sliding door system allowed him to completely seal out cold drafts when necessary as well.
I have to look him up, he’ll likely be in his 90’s, but sharp as ever I’m sure (as will be you, judging from your comments!).
As for supplemental use of UVB bulbs, much would depend upon how well sun exposure could be arranged…a UVB meter would be most useful and interesting to experiment with.
Best regards, Frank Indiviglio.