The UVB Varanid debate !

[formica]

Originally Posted by infernalis

You have that backward, mercury vapour lamps were invented 30 years prior to metal halide lamps.

A mercury vapour lamp has no halides (metal salts) in the plasma arc tube, Metal halide lamps are mercury vapour lamps with an additional metal salt compound (halides) added to the amalgam to broaden the spectral output.

One of the factors that caused experimentation with the arc tube contents was that a raw mercury vapour lamp output very high UV that would be harmful to stare into the bulb for any length of time, The first solution was to coat the glass envelope (outer bulb) with a UV reactive phosphor, that's how modern day florescent bulbs were born... the main difference between a florescent bulb and a mercury vapour bulb is the gas pressure inside the lamp. A MV lamp has very high pressure inside the arc tube, and generates such an intense heat that the amalgam must be contained in a quartz tube as the temperatures achieved in operation will melt standard silica glass, the low pressure content of a florescent lamp generates far less heat, so standard glass works fine.

However, the phosphor coatings were inefficient compared to doping the mercury itself, this is why we almost never see a frosty white coating on a metal halide lamp, but almost always see a frosty white coating on mercury vapour lamps.

From a manufacturing standpoint it's cheaper to make the metal halide lamps, a minuscule grain of halide salt is a lot cheaper than a whole coating of phosphorescent materials, and less harmful to the environment when the lamp is no longer usable.

I see interesting - i think perhaps I have been mis-sold a halide lamp as a mercury vapour, I have one which has Xenon mentioned in the specs, and is clear glass, but I bought it as a mercury vapour, turned out to be useless in my paludarium (no growth whatsoever) and I switched it out for 6000K LED's, always wondered why!

[infernalis]

The easiest telltale sign is that a mercury vapour lamp will have a clear arc tube, a metal halide will have white ends on it.

[murrindindi]

These are a few that are available currently in the U.K...


Metal Halide Bulbs - Reptile Lighting - Blue Lizard Reptiles - Reptile Shop

As already stated, they are the closest thing to natural unfiltered sunlight at the present time. I know London Zoo were intending to install metal halides in all the diurnal basking reptiles enclosures (info from Dr. Richard Gibson, former curator of reptiles at that establishment), though I haven`t visited for several years so not sure if they`ve actually done so?
I don`t doubt Bryan Grieg Fry`s thoughts for one moment, but I`d be interested to hear whether tests have been carried out on captive Varanids kept under what`s now considered "fully supportive" conditions in order to compare the results (I suspect there haven`t been too many at all)?
EDIT: For Wayne: That was a very informative reply about the differences between metal halides and mercury vapour bulbs. Unfortunately, no smilies available yet, including the "thumbs up".... So Thumbs up, and thanks from me!!

[formica]

surely there must have been a control, in order to be able to say that it has a positive influence on white cell counts, thats pretty basic scientific process...

[murrindindi]

Originally Posted by formica

surely there must have been a control, in order to be able to say that it has a positive influence on white cell counts, thats pretty basic scientific process...

I think you misunderstood what I was asking; there ARE articles re UVB exposure and captive Varanids, but they were not all carried out on animals we now consider to have been properly supported to make comparisons between those with access to real or artificial sunlight and those without but offered "proper" basking temps, humidity, whole prey diets, etc, etc (or maybe I`ve missed them)?

[formica]

Originally Posted by murrindindi

I think you misunderstood what I was asking; there ARE articles re UVB exposure and captive Varanids, but they were not all carried out on animals we now consider to have been properly supported to make comparisons between those with access to real or artificial sunlight and those without but offered "proper" basking temps, humidity, whole prey diets, etc, etc (or maybe I`ve missed them)?

not seen any reference to basking temps in either of the papers i've read on the subject (both in this thread) - I hope that the ( http://varanidae.org/1_2-Current_Research.pdf ) research is completed/published sometime soon, its been a few years now...perhaps they will include that information

[mdfmonitor]

Originally Posted by murrindindi

I think you misunderstood what I was asking; there ARE articles re UVB exposure and captive Varanids, but they were not all carried out on animals we now consider to have been properly supported to make comparisons between those with access to real or artificial sunlight and those without but offered "proper" basking temps, humidity, whole prey diets, etc, etc (or maybe I`ve missed them)?

That's what i was thinking, nicely put!

Also taking blood regularly does that not stess them? or do they get use to been grabbed & blood taken every few weeks?? i wonder what effect that has on ther chemistry?

[murrindindi]

Only the abstract from a paper published in 2009 (not sure when the actual study was done?), but even at that time many zoos did not offer what we now know are "supportive" conditions. Some interesting info re offering some rodents in the diet as well as supplements to other (invert) prey.
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[V87]

This is a good read for those interested UVB and UVA are very important

http://www.ivis.org/journals/exoticDVM/9-3/Brames.pdf


Sorry if it has been posted before

[infernalis]

I have always been very careful about what I say in the UV dabate discussions, But I have made up my mind that I'm going to be more pro-uv anymore.

It's only common sense, the UV index in the tropics is unreal compared to anywhere else in the world (excluding the poles) how can anyone say these animal's are not getting UV in the wild...?

[V87]

Originally Posted by infernalis

I have always been very careful about what I say in the UV dabate discussions, But I have made up my mind that I'm going to be more pro-uv anymore.

It's only common sense, the UV index in the tropics is unreal compared to anywhere else in the world (excluding the poles) how can anyone say these animal's are not getting UV in the wild...?

All animals get it .... Just wether they NEED it ....

IMO they do ....

[mdfmonitor]

Just put a couple of compact uvb bulbs in this am on one side, need a daylight bulb to hide some of the green light though!

[infernalis]

Originally Posted by V87

All animals get it .... Just wether they NEED it ....

IMO they do ....

I concur

Millions of years of evolution, diurnal animals living and thriving under a strong sun, ..

I'd say it's a huge mistake to deny them.

[B_Aller]

Originally Posted by infernalis

I concur

Millions of years of evolution, diurnal animals living and thriving under a strong sun, ..

I'd say it's a huge mistake to deny them.

To me the question is..Does the effort and money spent on these bulbs ACTUALLY translate into healthier animals. We're still talking man made UV bulbs that only provide a tiny fraction of the beneficial elements of the sun.
To me there are more important factors in the lives of most captives. I personally would rather spend my money and time providing larger more useful enclosures than dropping hundreds or thousands a year on questionable bulbs.
I don't deny that the animals obviously have evolved to utilize UV, for me, I have not seen positive results from these bulbs, only from better overall conditions for the animals. The problem is that many will slap a bulb in a shite enclosure and feel like they have it covered. Again, none of the long term breeders that I hang with bother to use any of these bulbs, yet are more successful overall than those who do use them.
I've used many of the available UV bulbs and have never seen any noticeable difference in my animals health, coloration, appetite or behavior, so I stopped worrying or thinking about them long ago. Just my 2 cents.
Best.

[formica]

Originally Posted by infernalis

I concur

Millions of years of evolution, diurnal animals living and thriving under a strong sun, ..

I'd say it's a huge mistake to deny them.

I think there's allot we can learn from paying attention to the environments that animals have adapted to, we already understand that even our best attempts at producing the best climate for (any captive reptile), is far from what their physiology is adapted to work with.

Considering how much monitors seem to be able to absorb the inadequacies of their captive environments, it doesn't surprise me that some can appear to do well without UV - but, we have no way to know how the monitor is actually feeling

Pain, Fatigue and Stress, when endured for a long peroid of time, even at very low levels, can have massively adverse affects on quality of life, in humans there are recognized conditions (eg Chronic Fatigue), which can have horrible effects on people, even tho the pain and fatigue which is experienced is a relatively low level (compared to say a broken leg), and life seems to go on as normal to anyone viewing from the outside.

The fact that white blood cell counts are found to be higher, is a very good indicator that those monitors in question could be ''feeling'' much better than those with lower levels - it is well know that depression in humans and many other animals, results in a reduced immune response and lower white cell counts, such links between psychology and physiology are frequently found to work in both directions

Even if our attempt at providing correct UV levels fails to meet the level found in the wild, I see no reason not to try and work with what we have, and make every effort to improve their living conditions, no matter how small those changes may appear

....give it another 5 years, and I feel certain that LED technology will have developed far enough to do an even better job than halides (probably sooner, UVA LED's already exist at low prices, UVB are falling steadly, although still >300$ per W), 10 years and we can probably simulate a true African savannah sun, with a little luck, some of our animals may still be around to benefit from it.