The Truth About UVI Unleashed

02/11/2019

Only few topics in Chamaeleoculture are so controversial such as the debates about UV. During my most recent expeditions to Africa and Arabia (incl. Socotra), I made many observations and measurements...

Let me share few of them though they are quite obvious...

1. The UVI in lowlands is lower than in the highlands: sea level UVI in Socotra and Oman and Yemen is 8,5-9 while UVI at middle altitudes of above 1000m a.s.l. is 12-14 and UVI of high Kenyan highlands around 2850m a.s.l. is 17: early morning and late afternoon sun (approximatel).
2. One hour after sunrise and one hour before sunset) gives just half of these values
3. The UVI is drastically reduced by cloud cover - to 0,5-1 and in rain it is not even measureable.
4. The UVI in the shade in the bush is even under no cloud cover in the lowlands 0,5-1 and in the highlands 1-2.

The influence of UV (320nm-400nm wavelength) on chameleons is both positive and negative.
UV is essential for the chameleons for the metabolism of vitamin D3, Calcium and Magnesium. Without this process running, the animals suffer heavy health problems such as MBD that lead to painful and pitiful bone deformities and even death.
But, UV also damages the DNA and is a strong mutagene, it causes cancer, being cytostatic, it kills cells and has antiseptic properties in killing bacteria and fungi.

Chameleons need UV for the named benefits but it also kills them and causes mutations.

They protect themselves against its negative influence by the production of Melanine in the skin and in the peritoneum - sic! The doses of UV they get are a byproduct of their basking or exposure to sun.

The question is therefore, how much they bask...

The highland (montane) chameleons (such as Trioceros narraioca, ntunte, hoehnelii, jacksonii, sternfeldi; Kinyongia boehmei, tavetana, vosseleri, matschiei; Chamaeleo
calyptratus, chamaeleon orientalis etc.) tend to bask in the morning as a rule to gain the necessary comfortable temperature after a cold night (under 15'C up to freezing point) and during the day, they acquire the warmth from the air around and do not bask at all (unless it is cloudy or cold or after rain - all when it gets "cold").

The lowland species do ten not to bask at all except after heavy rain. I have observed C. monachus, sleeping at terminal parts of the branches to flee into the shade of the bush or canopy immediately after having been exposed to sun.

So, the chameleons do not as a rule bask as much as we suspect, but stay a vast majority of the time hidden from it, effectively at UVI 0,5 to max 2.

What are the implications in captivity?

There is no necessity to bake them under strong UV sources that can even cause bad skin burns when the animal gets closer as the levels of UVI in the immediate vicinity of the source can exceed the highest measured levels from the wild by several times.

On the other hand, we need to provide UV at lower intensities for the chameleons to feel comfortable and to foster the correct metabolism...

As a backup solution, it is advisable to deliver tiny amounts of vitamin D3 through supplementation.

Author: Petr Nečas