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Below is one of the most popular discussions around UVB. Please feel free to add to it.
Ok this one gets talked to death, but we still don't have a consensus. So let's discuss it here under its own heading. Here is some factual information about the light spectrum.
Light is generally considered an electromagnetic wave.
Wavelength is measured in Nanometers (1/1000000000 meter)
IR is 700nm - 1500nm
Visible light is 400nm - 700nm
UVA is 320nm - 400nm
UVB is 286nm - 320nm
UVC is 200nm - 286nm
VUV is 100nm - 200nm (vaccuum UV)
Window glass through at least 50 websites I reviewed tonight, ranging from hobbyist, manufacturers to collegiate physics presentations on the web all agree that there isn't a significant amount of UVB light passed through. The problem with this statement is that the majority of sights just take this as common knowledge and move on. A few sites refer to the state of the energy. I will give a quick explanation
Light hits a "transparent" object, if the energy level of the light matches it doesn't pass through. Glass lets through light that is above 350nm in general. This is to say that a lot of the light is absorbed or reflected, but what I can't find is how much is absorbed and reflected.
At this point it requires a major study of the chemical make-up of glass and the intensity of the light and a bunch of heavy math that I am not really capable of doing at this time.
What I have discovered through Melissa Kaplan's fine site Anapsid.org is a couple of charts that give us a breakdown of natural sunlight and things it pass through
A single pane window should transmit about 5% UVB, modern double pained windows will allow about half that, if they're tinted even less. If the light goes through a screen or a tank wall cut even more. So with single pane window with access to direct sunlight for part of the day you get the same output as a reptisun 5.0 bulb at 12 inches away.
Now onto some theories....
Barb Reader has had Timmy the Cooter for nearly 43 years. He started as a dimestore turtle. For the majority of Timmy's life he has had just window light. From Barb's story it took Timmy several years to reach adult size.
I have had Uzumaki the Cooter for 8 months. He has had a Reptisun 5.0 bulb on for 14 hours a day, which he usually sits about 5 inches away. My turtle started at 1.75 inches and is now 4.5 inches. At his current rate of growth he will be a full grown adult this time next year.
My theory is that the turtles grow a lot faster when subjected to longer and more regular UVB exposure. The amount of UVB given off by the light and the assumption that the window was single paned is close, just the actual amount of time the turtle is exposed differs.
So is this form of accelerated growth good? normal?
Anybody have a turtle before these new crops of lights came out and has gotten one since and noticed this?
Some of the sources I used above
http://www.maui.net/...html#sensometer
http://www.anapsid.org/uvtable.html
Good work Michael. Thanks for the research about light and glass. However, I have a question about your theory of growth rate of your cooter. I think the first few years turts grow faster and I don't think this growth rate will continue. Also, UVB will not alter the growth rate (that is what you are proposing: your coot vs. Timmy - your turt will reach adulthood quicker). Here is why I oppose your theory.
The first point: to reach maturity in size, it has to do with time. I mean if we feed a human the best foods and optimal condition, it's still going to take 16-20 years for a male human to grow to it's full size. If someone grew up with a lot of sun, that would say they would reach adulthood quicker? Hmmm. [
The second point is the better nutrition (Ca and Vit D), the better the growth (i.e. bigger and stronger bones/shell). This is taken as a fact in most literature in the field (Ca + VitD = strong bones & bigger), but not necessarily maturing faster.
I think you are mixing up point one and point two. I think your cooter will be bigger in the end and healthier with the better source of Vit-D from UVB. But it will still take 'X' number of years for your cooter to reach maturity. No matter how much UV and nutrition it gets. All this does is make it bigger and stronger, but does not make it grow faster.
What you do think Michael?
Cheers,
JJ
Isn't bigger the same as growing faster? I agree with Michael about Timmy; I figured he got his original UVB through old fashioned plate glass. It still wasn't much compared to outside. My baby RES living outside have gone from 1 inch to 2 1/2- 3 in in six months, with every other day feedings. They are also almost black from sun exposure, as they spent about six hours every day in full sun. They are NOT comparable to wild hatchlings as they don't have to hunt down their food or hide from predators.
In humans, we have found that better nutrition leads to both taller growth and earlier puberty. I am pretty sure the sun is not a factor, but remember that we, too, need D3 for growth, and in colder climates it is often added to milk so that we get it even in the absence of sufficient sun exposure.
Bobbie
Also keep in mind that there are two schools of thought about UVB and D3. It is generally accepted that most reptiles need UVB to synthesize Vit D3. There is anothe rschool of thought though that beleives the same can be accomplished through diet.
This is getting to be an even more popular theory withthe Eastern Species of Box Turtles. Most of these animals very rarley sun themsevles and live in forests with thick canopies.
while I personally agree that we should do the UVB anyway it just gives us something to think about!!
In my research, and this was more on the reptile than the physics it states that the lights we provide simulate noon time sun all day. While in nature, the levels of UV and other lights change by the position of the sun.
Also another factor is the food that is fed to the turtle. Reptomin now is a probably a lot better than pelleted foods that were available in the 60s. I can't quite remember what Barb said about what Timmy was fed when young, but her current diets are excellent. But it seems to me that humans and other animals grow a lot faster when they are provided with more nutrients and the means to metabolize those nutrients.
We hear a lot about people making their tortoises grow too fast. However the tortoises get pyramiding and shell deformities. But is this the result of just too much protein/fat or is it that their isn't enough calcium/d3 metabolizing going on at an equivalent rate.
For simplicity lets say that a tort needs a ratio of 2protein - 4calcium to maintain a slow even growth. Now lets say we increase the protein intake with dogfood. Lets assume that dogfood is 12protein - 8calcium, this gets the turtle to maturity 6 times faster, but with deformities. Is it concevable that if the tort was able to metabolize the 12 protein and 24calcium that it would grow normally but 6 times faster? So to increase the amount and duration of UVB should raise the metabolization of calcium, making said turtle grow faster, without deformity.
***Please note - this ratio is a theoretical argument and in no way should be considered as a good ratio for tortoises, please review your species care requirements.
I believe that any studies into this would be cruel, so I guess we'll never really know, but I think that over-abundance of UVB light helps turtles grow faster.
Billy,
This talk of animals accquiring the vitamins and minerals through diet is good. But UV light gets to the surface in even heavily forested places and it even gets through clouds. So I believe that box turtles are still getting some/enough UV to metabolize their needs. While raising your baby, I bet he will grow a lot faaster than his wild counterparts for 2 reasons, abundance of food and abundance of UV light. Even with shade in a turtle pen, it'll get more direct light than in the woods...
Also on anapsid.org in one of the articles they did some tests with lizard basking spots. cold bright place vs. warm dark place and the lizards always chose the bright place, somewhat proving that the reptiles instictively knew how to regulate their UV exposure.
Ok this one gets talked to death, but we still don't have a consensus. So let's discuss it here under its own heading. Here is some factual information about the light spectrum.
Light is generally considered an electromagnetic wave.
Wavelength is measured in Nanometers (1/1000000000 meter)
IR is 700nm - 1500nm
Visible light is 400nm - 700nm
UVA is 320nm - 400nm
UVB is 286nm - 320nm
UVC is 200nm - 286nm
VUV is 100nm - 200nm (vaccuum UV)
Window glass through at least 50 websites I reviewed tonight, ranging from hobbyist, manufacturers to collegiate physics presentations on the web all agree that there isn't a significant amount of UVB light passed through. The problem with this statement is that the majority of sights just take this as common knowledge and move on. A few sites refer to the state of the energy. I will give a quick explanation
Light hits a "transparent" object, if the energy level of the light matches it doesn't pass through. Glass lets through light that is above 350nm in general. This is to say that a lot of the light is absorbed or reflected, but what I can't find is how much is absorbed and reflected.
At this point it requires a major study of the chemical make-up of glass and the intensity of the light and a bunch of heavy math that I am not really capable of doing at this time.
What I have discovered through Melissa Kaplan's fine site Anapsid.org is a couple of charts that give us a breakdown of natural sunlight and things it pass through
A single pane window should transmit about 5% UVB, modern double pained windows will allow about half that, if they're tinted even less. If the light goes through a screen or a tank wall cut even more. So with single pane window with access to direct sunlight for part of the day you get the same output as a reptisun 5.0 bulb at 12 inches away.
Now onto some theories....
Barb Reader has had Timmy the Cooter for nearly 43 years. He started as a dimestore turtle. For the majority of Timmy's life he has had just window light. From Barb's story it took Timmy several years to reach adult size.
I have had Uzumaki the Cooter for 8 months. He has had a Reptisun 5.0 bulb on for 14 hours a day, which he usually sits about 5 inches away. My turtle started at 1.75 inches and is now 4.5 inches. At his current rate of growth he will be a full grown adult this time next year.
My theory is that the turtles grow a lot faster when subjected to longer and more regular UVB exposure. The amount of UVB given off by the light and the assumption that the window was single paned is close, just the actual amount of time the turtle is exposed differs.
So is this form of accelerated growth good? normal?
Anybody have a turtle before these new crops of lights came out and has gotten one since and noticed this?
Some of the sources I used above
http://www.maui.net/...html#sensometer
http://www.anapsid.org/uvtable.html
Good work Michael. Thanks for the research about light and glass. However, I have a question about your theory of growth rate of your cooter. I think the first few years turts grow faster and I don't think this growth rate will continue. Also, UVB will not alter the growth rate (that is what you are proposing: your coot vs. Timmy - your turt will reach adulthood quicker). Here is why I oppose your theory.
The first point: to reach maturity in size, it has to do with time. I mean if we feed a human the best foods and optimal condition, it's still going to take 16-20 years for a male human to grow to it's full size. If someone grew up with a lot of sun, that would say they would reach adulthood quicker? Hmmm. [
The second point is the better nutrition (Ca and Vit D), the better the growth (i.e. bigger and stronger bones/shell). This is taken as a fact in most literature in the field (Ca + VitD = strong bones & bigger), but not necessarily maturing faster.
I think you are mixing up point one and point two. I think your cooter will be bigger in the end and healthier with the better source of Vit-D from UVB. But it will still take 'X' number of years for your cooter to reach maturity. No matter how much UV and nutrition it gets. All this does is make it bigger and stronger, but does not make it grow faster.
What you do think Michael?
Cheers,
JJ
Isn't bigger the same as growing faster? I agree with Michael about Timmy; I figured he got his original UVB through old fashioned plate glass. It still wasn't much compared to outside. My baby RES living outside have gone from 1 inch to 2 1/2- 3 in in six months, with every other day feedings. They are also almost black from sun exposure, as they spent about six hours every day in full sun. They are NOT comparable to wild hatchlings as they don't have to hunt down their food or hide from predators.
In humans, we have found that better nutrition leads to both taller growth and earlier puberty. I am pretty sure the sun is not a factor, but remember that we, too, need D3 for growth, and in colder climates it is often added to milk so that we get it even in the absence of sufficient sun exposure.
Bobbie
Also keep in mind that there are two schools of thought about UVB and D3. It is generally accepted that most reptiles need UVB to synthesize Vit D3. There is anothe rschool of thought though that beleives the same can be accomplished through diet.
This is getting to be an even more popular theory withthe Eastern Species of Box Turtles. Most of these animals very rarley sun themsevles and live in forests with thick canopies.
while I personally agree that we should do the UVB anyway it just gives us something to think about!!
In my research, and this was more on the reptile than the physics it states that the lights we provide simulate noon time sun all day. While in nature, the levels of UV and other lights change by the position of the sun.
Also another factor is the food that is fed to the turtle. Reptomin now is a probably a lot better than pelleted foods that were available in the 60s. I can't quite remember what Barb said about what Timmy was fed when young, but her current diets are excellent. But it seems to me that humans and other animals grow a lot faster when they are provided with more nutrients and the means to metabolize those nutrients.
We hear a lot about people making their tortoises grow too fast. However the tortoises get pyramiding and shell deformities. But is this the result of just too much protein/fat or is it that their isn't enough calcium/d3 metabolizing going on at an equivalent rate.
For simplicity lets say that a tort needs a ratio of 2protein - 4calcium to maintain a slow even growth. Now lets say we increase the protein intake with dogfood. Lets assume that dogfood is 12protein - 8calcium, this gets the turtle to maturity 6 times faster, but with deformities. Is it concevable that if the tort was able to metabolize the 12 protein and 24calcium that it would grow normally but 6 times faster? So to increase the amount and duration of UVB should raise the metabolization of calcium, making said turtle grow faster, without deformity.
***Please note - this ratio is a theoretical argument and in no way should be considered as a good ratio for tortoises, please review your species care requirements.
I believe that any studies into this would be cruel, so I guess we'll never really know, but I think that over-abundance of UVB light helps turtles grow faster.
Billy,
This talk of animals accquiring the vitamins and minerals through diet is good. But UV light gets to the surface in even heavily forested places and it even gets through clouds. So I believe that box turtles are still getting some/enough UV to metabolize their needs. While raising your baby, I bet he will grow a lot faaster than his wild counterparts for 2 reasons, abundance of food and abundance of UV light. Even with shade in a turtle pen, it'll get more direct light than in the woods...
Also on anapsid.org in one of the articles they did some tests with lizard basking spots. cold bright place vs. warm dark place and the lizards always chose the bright place, somewhat proving that the reptiles instictively knew how to regulate their UV exposure.
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