This subject is so varied and species specific it is usually treated in individual care sheets for each individual species. However there are some common threads that it is useful to discuss in one article to give a better overall understanding. This should help new owners decide on which is the correct equipment to purchase and existing owners to understand why we do the things we do and why some advice has changed over the years. We are lucky at Angell Pets to be able to draw on the expertise of our technical adviser George Angell. George is course leader at Abingdon and Whitney college and regularly lectures on all things herpetological. He has kindly written the following article which explains the mysteries of enhancing the health and wellbeing of our animals through correct heating and lighting and how the two interplay. Plus he is a bit more succinct than I am so this advice, whilst the same as I have been giving in the shop for years is much clearer than my ramblings!
UV to Infra Red Lighting
The subject of reptile lighting can be very confusing. White, red, blue, and green heat bulbs, UV lighting, LED lighting, heat mats and heat cables, heat rocks, ceramic heat emitters, halogen bulbs, mercury vapour, metal halide; the list goes on and on. But what do I need to get for my reptile or amphibian?
Well first we need to understand why we need to provide any of this equipment at all. Nearly all reptiles are ectotherms, meaning they use external sources of energy for heat. In the wild, reptiles will use the sun’s energy for this purpose, but in captivity they do not have access to the sun. We need to use a range of equipment to try and replicate the energy from the sun.
This solar energy hits the atmosphere and we see it as light. However, there are elements of the suns energy which we cannot see with the naked eye and these are in the form of UV (ultra violet) and infra-red. These are all forms of radiation from the sun, but they have different wavelengths. UV light is short wavelength in the range of 200-400nm, visible light is 400-700nm and infra-red radiation is in the range of 700-1 million nm.
If we are to try and recreate the sun’s energy inside our vivarium, we need to try and produce the full spectrum of light for our reptiles. This includes providing UV light, visible light, and infra-red light.
Let’s focus on the higher energy end of the relative section of the electromagnetic spectrum. UV light can be split into 3 categories. UVA, B and C. In the picture below is shown the UV categories and their relative wavelengths, as well as the other important types of light radiation that we will deal with later.
UVC, the highest energy form, is harmful to cells as it begins to breakdown the DNA molecules inside the cell. We do not want to be producing this in our reptile enclosures. Most equipment manufacturers will ensure their lamps are not producing any UVC.
UVC lamps are used in the animal industry however but mainly as a disinfectant bulb, particularly in fish filters so it is always worth buying your lamps from a reputable pet shop and be wary of buying cheaper bulbs from the internet.
UVB is essential for reptile health and wellbeing. UVB is critical in the process of metabolising calcium obtained in the diet. UVB (290-315nm) enables the reptile to convert cholesterol in the skin into pre-vitamin d3. This undergoes a temperature dependent reaction to convert to vitamin d3. This is metabolised in the liver and the kidney to produce the hormone calcitriol which, in turn controls calcium metabolism. UVB has also been shown to increase the skin’s barrier functions, increase the pigments in the skin and to act as a mild disinfectant for bacterial and fungal infections.
The diagram below shows why both ends of the light spectrum are important to this function
UVA light, whilst not visible to the human eye, can be seen by reptiles and amphibians and is used in communication, recognition of food items and recognition of conspecifics
We now know we need to provide UV light in the forms of UVA and UVB but how much? This is very dependent on where our reptile/amphibian comes from in the wild. How much sunlight, and as a result, UV light, is it exposed to in its natural habitat and can we mimic that in captivity?
Bearded dragons come from the deserts of Australia. They naturally have large amounts of sunlight and UV light every day. A nocturnal, forest dwelling gecko species, such as a crested gecko, will only see glimpses of sunlight through the canopy of the trees as it is hiding under a leaf during the day.
Many UV equipment manufacturers have marketed their lamps to be easier to understand and have tried to aim them toward certain habitats. For example, there are “desert” style lamps that emit higher levels of UV compared to “jungle” or “natural sunlight”. These used to be marketed as 10%, 5% and 2% UVB lamps. This indicated how much of the lamp output was in the UVB range of wavelengths. This has now largely changed, and lamps are marketed differently for different brands. For example Exo Terra now use 100, 150, and 200 (the amount of UVB recorded 10cm away from the lamp) and arcadia use desert, forest and shade dweller.
The most important thing to find out before committing to purchasing a UV setup is the natural range of UV for our reptile. Lots of research has gone into this in recent years and many of the commonly kept species have been categorised into 4 groups. These categories are called Ferguson zones and they differentiate the group depending on their natural UV levels in their natural range. This is measured as a UV index using a UVI meter. For example, nocturnal gecko species are Ferguson zone 1. They do not encounter large amounts of UV light in nature so need a UV index of 0-1.0. The bearded dragon however is in Ferguson zone 3, needing a UV index of 2.9-7.4. This is because they openly bask in the hot sun of the Australian desert.
Once we know what Ferguson zone suits our reptile or amphibian species, we can begin to plan our basking area. The Ferguson zone will also indicate how our reptile gains its energy. If it is in Ferguson zone 1-2, it is very unlikely to get direct sunlight in its natural range. This could be because it is nocturnal and doesn’t openly bask in the sunlight, or it could be a jungle species that lives under the canopy, so sunlight is filtered and reflected by the leaves above. If your reptile is in Ferguson zone 3 it is likely to be basking in direct sunlight and actively coming out during the day to bask. Fergusson zone 4 animals spend almost the entire day exposed to strong sunlight. We can provide the UV accordingly.
For a reptile that is in Ferguson zone 1 or 2, we can provide UV by the “shade” method. This is where we provide low levels of UV, over most of the enclosure and the animal can get away from the UV in hides or in the shade from plants/enrichment. For animals in Ferguson zones 3 and 4 we provide UV by the “sunbeam” method. As we discussed, these animals bask in direct sunlight. Natural sunlight contains UV, visible light and infrared (heat) light which we will discuss in more detail later. So, for us to provide high levels of UV, in the UV index range of 2.9-7.4, we provide it in the basking area at the hot end of the enclosure. We then provide a shaded end at the other end of the enclosure where the animal can regulate its UV exposure.
Now we have decided what Ferguson zone our reptile/amphibian belongs in and we have decided how we will provide the correct UV index in the enclosure according to the animal’s behaviour, we can choose the type of lamp. There are many methods to provide UV to our animals, and each has its advantages and disadvantages. Unfortunately, there are many conflicting opinions on the internet about which method is best and it can get very confusing. Ultimately, it doesn’t matter what type of UV lamp we are using, if we are providing the correct UV index for our species.
The usual way to provide UV in reptile enclosures currently are to use compact UV lamps (swirly bulbs), T8 tubes, T5 tubes, mercury vapour or metal halide. All have their advantages and disadvantages and we will discuss them in a bit more detail later but before we start it is important to note that levels of UV deteriorate over distance and time. The UV levels your reptile receives 30cm away from your lamp will be different to what they receive 10cm away. Also, what the animal receives 6 months later will be less at any distance. It is worth checking your lamp output regularly.
UV compact lamps are what they say on the tin. They are small, compact lamps that have been designed to fit inside a canopy which can sit on top of an enclosure. They are great for using in small enclosures or for additional UV at the basking site. However, they don’t project their UV very far so the basking area needs to be relatively close to the bulb.
T8 tubes are the thicker tubes, approximately 1 inch in diameter. These are used by a large proportion of the hobby. They are often the cheaper options of UV available and they can provide reasonable levels of UV for most enclosures. Again, UV deteriorates over distance and these lamps don’t project the UV as far as some others but can provide adequate UV for shade dwelling enclosures and if used correctly, for the sunbeam method.
T5 lamps are the higher end type of fluorescent tube and are more powerful than the compact lamps and T8 bulbs. They can project their UV further so the animal doesn’t need to be as close to get the same level of UV. They are slightly more expensive, though recent developments and a push from the reptile trade for better equipment in the hobby is making these more available to every keeper. These can be used for both shade dweller and sunbeam methods providing the correct intensity bulbs are chosen. Both T8 and T5 lamps need a separate controller that is mounted outside of the vivarium. Some of these controllers can be used in any type of habitat but some can only be used in arid environments (i.e. cannot be sprayed with water as the fittings are not sealed) so do check first which one to use.
Mercury vapour lamps are large bulbs. They provide UVA, UVB, visible light and infrared light (heat). They are self-ballasted, meaning they can be put into a standard reptile light large eddsion screw fitting; however, they cannot be controlled on a thermostat. This is because the ballast requires constant voltage to be able to start the bulb and keep it running, and the thermostat will cut that power. This will cause the lamp to cut out and restart which will shorten the lifespan of the bulb. As they are such large bulbs, generally 80-160W, they provide lots of heat too (the glass surface gets very hot). This fact combined with not being able to be combined with a thermostat means they are often unsuitable for use inside a vivarium. They are however, very useful for large enclosures such as a room, or for open topped enclosures like tortoise tables or terrapin enclosures.
Finally, metal halide lamps are similar to mercury vapour in that they produce UVA, UVB, visible light and infrared, except that they require the use of an external ballast. This ballast effectively amplifies the electricity from your supply in order to start the bulb. This means the bulbs themselves can be lower wattage which helps to reduce the electricity bill. However, they still produce large amounts of infra-red radiation and cannot be used on a thermostat due to their ballast. Therefore, they are best used in open top enclosures or larger enclosures like mercury vapour. Trials have shown that they project UV light and visible light much further into the enclosure than other methods.
We know our Ferguson zone, we know how we will setup our UV lamp, either shade method or sunbeam method and we have decided on our UV lamp, now we need to set up the equipment and ensure the measured UV index is correct. For our bearded dragon we know it is Ferguson zone 3, needing a UV index of 2.9-7.4. It is best to use the sunbeam method, and as a result we will use a “desert” T8 or T5 bulb in our vivarium at the basking area in the hot end. Once we have this setup, we will turn it on and allow the lamp to “burn in”. Often UV lamps require a time to stabilise the output of UV. This is often around 100 hours of being on. After this period the amount of UV the lamp produces will be more stable and will then start to decline slowly over the lifecycle of the lamp. We will then check our UV index in the basking area, where the animal will sit, and it is hopefully reading within the range of 2.9-7.4.
Now for visible light. This is a developing area in reptile keeping as, for many years we have been happy being able to see our reptiles with the visible light that is also produced by our fluorescent UV tubes. However, more and more research is being done into the benefits of providing well-lit vivariums. A bright enclosure not only allows us to see the enclosure better but also stimulates more natural behaviours from our animals, even if they are a nocturnal species. Nocturnal species have been shown to react to light levels and carry out a behaviour known as cryptic basking. This can be, for example, where they are hiding under a leaf but have a foot sticking out. The reptile is therefore able to utilise light and infrared radiation, just as if it was basking in the open.
As we discussed the sun has UV, visible and infrared light all in one. But we need to provide multiple bulbs to produce the full spectrum effectively. Visible light is often added to an enclosure using LED lamps. These are high output, efficient lamps that provide a bright light. Many basking lamps also give out light in the UVA range.
We measure light levels in lumens and also the colours of light in degrees kelvin. As shown in the illustration at the start of the blog, visible light at different wavelengths appears to us as different colours, i.e.the colours of the rainbow. Reddish light (often seen at sunrise and sunset), shows when blue light is filtered out, which is around 3000K. Bluish light shows when the red light is filtered out which is often when it’s cloudy (10,000K). Bright sunlight is around 6500K and this is generally what LED manufacturers aim for. Bright, well-lit enclosures also have benefits for naturalistic or bioactive enclosures that contain live plants. Live plants require light in the visible light range of wavelengths in order to photosynthesis. By producing bright, full spectrum lighting, we can improve the health of our plants. The pros and cons of naturalistic and bioactive enclosures is another whole article in itself! To complete our lighting setup, we need an infra-red heat source. Like UV, infrared can be split into 3 categories. Near infra-red, middle infra-red and far infra-red.
These 3 categories all provide warmth to the reptile/amphibian; however they provide it in different ways. The near/short infra-red is the wavelength that is closest to visible light. We cannot see it, but some reptiles can, and they will use this when choosing where to bask. This wavelength of infrared also penetrates the tissue of the reptile and has a deeper warming effect on the tissue than the other types of infrared. Mid-infrared penetrates the skin less than near infra-red but still has a moderate warming effect and far infra-red penetrates very little but has a surface warming effect for the items in the enclosure.
The different types of heating/lighting equipment we use produce different types of infra-red radiation. Again, the sun produces the whole range of this energy, along with UV light and visible light so we want to try and replicate that in our enclosures and provide a full spectrum of infra-red radiation too.
To provide near infra-red we can use incandescent bulbs such as halogen bulbs, or basking bulbs. These produce visible light that we can see, but the filaments inside them are very slowly burning and also producing near infra-red energy. As we discussed, this type of infra-red radiation penetrates the skin deeply and provides positive influences on the animal’s blood vessels and sub-cutaneous functions. For pre-vitamin d3 to convert to vitamin d3, the process requires warmth as shown in the illustration below.
To produce mid infra-red, we can use “deep heat projectors”. These do not produce visible light but do produce near and mid infra-red. This helps to provide heat deep into the tissue of the animal without disturbing the day-night cycle and also without producing extra visible light. This can be an advantage if you already have a very bright basking area by using multiple UV bulbs, LED bulbs and incandescent bulbs, but you still need to increase the basking temperature.
Finally, to produce far infra-red we can use equipment like heat mats, ceramic heat emitters or heating cable. This type of infra-red radiation is the type of infra-red that is reflected back into the environment once the sun has gone down. For example, a rock that has been under the sun all day and has been warmed by the sun’s energy. Once the sun goes down and external air temperatures start to decrease, the rock releases its energy back into the environment and cools down. This energy is in the form of far-infrared radiation. In our enclosures we can provide this by using the equipment listed above and this can help maintain temperatures overnight and provide a warm area for the animals to hide or move around in whilst still allowing a day/night cycle of visible and UVB light.
The reptile trade is developing equipment all the time. Recently, there has been a big push in the trade to try and move away from the old style of heating an enclosure using a heat mat at one end and that’s it. Now we understand more about the wavelengths of infra-red and how the provision of near infra-red wavelengths has so many benefits for reptiles and amphibians, we are trying to give a good full spectrum of lighting. However, to do this it is important that the heating elements of our spectrum should be on a thermostat. This ensures that the temperature doesn’t get too hot, and that the equipment is able to turn off when the enclosure gets above the required temperature for the species. In the wild, the animal would move itself into shade and escape the heat, or burrow into the substrate. However, without a thermostat turning our heating off in our enclosure, it can become like an oven with nowhere to escape to. Reptiles and amphibians can tolerate low temperatures for some time but over temperature can kill in minutes if extreme.
Near infra-red sources like incandescent light bulbs are best used on a dimming thermostat. This is because they also produce visible light (even the red lamps produce red light that we can see as well as infra red that we can’t). The light can be dimmed down by reducing the voltage applied and as a result the amount of infrared radiation is also dimmed down. If we were to use the other types of thermostats (pulse proportional or on/off) then the light will be flickering and it is likely to blow the bulb, meaning it needs replacing. This type of thermostat also gives the finest level of control as it keeps the highs and lows of temperature change closer and thus a more stable temperature overall. As the lamp spends a lot of time with the voltage applied to it lower than the maximum it is rated for the life of the bulb is also extended, sometimes quite significantly.
Heating elements like ceramic heat emitters are best used on a pulse proportional thermostat. This is where the electricity supply is on and off in short pulses. For example, when the temperature is too cold, the “on” pulse is longer than the “off” pulse. Then when the temperature is approaching the correct temperature, the pulses are about the same, 50/50. When it is too hot the “off” pulse is longer than the “on” pulse. This is why we use this type of thermostat with a far infra-red heating element as with an incandescent light bulb, this is likely to significantly reduce the life of the bulb.
The on/off thermostat is generally used for heat mats and cables and is the most basic of the thermostats. The heating element is on full power until it reaches temperature, and then it is completely off. This creates large peaks and troughs in temperature and is the least stable level of control. Heat mats can also introduce the chance of a phenomenon called “thermal blocking”. This is where the enclosure is cold, so the reptile moves to the heat mat to warm up. The heat mat is mainly producing far infra-red. It is not warming the air in the enclosure very much and not penetrating the tissue of the reptile. As a result, the reptile still feels cold, so stays on the heat mat. The heat mat stays on at full power as the thermostat probe thinks it is too cold because the reptile is sitting on the heat mat, blocking the heat warming the air temperature in the enclosure. As a result, the reptile can get burnt, even when using a thermostat. Therefore, if heat mats are used, it is often recommended to put them on the side of the enclosure so the animal cannot sit on them. This mainly effects large animals that can significantly cover the mat with their body.
That is an overview of lighting our reptile enclosures. It covers the principles of UV lighting, visible lighting and infra-red heating and the need to provide the full spectrum to our captive reptiles and amphibians. For detailed information on individual species the supplier should be asked for further advice. Animals should only be purchased from licensed suppliers who are able to give advice on the animals they are selling. Licences are graded from one to five stars. Always choose a 5 star supplier.
George Angell Bsc (Hons)
Countryside Management Course Leader & Lecturer
Abingdon and Witney College in Partnership with Oxford Brookes University