The sun provides us with visible light but also provides heat, UV-A and UV-B through the range of terrestrial wavelengths that reach our planet through our planet.

With the release of the Arcadia Reptile Deep Heat Projector® in 2017, there has been increasing conversation within the reptile community about the correct use of infrared heating for our reptiles. Many people have asked which animals are suitable for keeping with the Deep Heat Projector (DHP). Lizards, snakes, amphibians, invertebrates and even birds and mammals can be kept successfully with the DHP. The reason for this? The wavelengths produced are similar to those that reach the earth from our sun.

It is important to change the way we think about heat. There is not just one type of heat but in fact a range of different wavelengths, with different properties and interactions. As humans, it is easier for us to understand things we can see for ourselves. This is much easier when we look at different colours of visible light, because we can distinguish a ‘cooler’ blue light from a ‘warmer’ red light. Heat is a little different because we can feel it but we cannot easily distinguish the different types. As we cannot see infrared, we find it more difficult to understand. We can however feel the difference between the types once we know what we are looking for, as you will see below.

What Exactly is Infrared?

Infrared a group of wavelengths beyond the visible light spectrum. There is some disagreement about the exact wavelengths that constitute ‘infrared’; it is stated as between 700/760 nanometres to 1 millimetre1. Infrared wavelengths are the primary terrestrial wavelengths known to penetrate the skin. This means that they are more effective at heating our animals5.

Within the infrared portion we then have Infrared-A, Infrared-B and Infrared-C.

This diagram shows the breakdown of the groups of terrestrial wavelengths.

electromagnetic, wavelengths
The range of electromagnetic wavelengths from ultraviolet, through visible light and into infrared2.

Infrared-A is also known as ‘near infrared’ or NIR for short. It is the shortest wavelengths within the group: 750-1400 nanometers. That is because it is the closest to visible light – that which humans can see. It has a high energy and as such is beneficial for animals. This is because the photons penetrate into the dermis of the skin as shown in the diagram below.

Then we have infrared B. This is between 1400 and 3000 nm. It does not push as far into the dermis but the wavelengths contain more energy within them, so they are also efficient.

You can feel Infrared-B & A, for example when you hold your hand out in the sunshine you can almost feel a prickle as it heats deep into the skin. Its pleasant feeling also causes animals, including ourselves, being drawn to sit in sunshine.

Finally, at the end of the spectrum, furthest away from visible light, we have Infrared-C. This is sometimes called ‘far infrared’ or FIR. Now, Infrared-C is an important group of wavelengths as it is these that are rereleased from the environment after the heat is absorbed as infrared-A & B. You know when you have a very hot sunny day? (Something we have had plenty of in the UK for the last few weeks)! Well, when you press your hand to the dark tarmac you feel that gentle warmth being released. That is Infrared-C. This energy release can continue for long periods and is why you do not get a sudden temperature drop after dark, especially in the tropics.

Living things also emit radiation in the FIR part of the spectrum. The heat sensing organs in snakes detect infrared energy being emitted by prey and the environment and so help them with both hunting and thermoregulatory behaviours2.


infrared, ceramic, ceramic heater, Deep Heat Projector
The varying penetration of infrared types into animal skin3.

Benefits of Infrared Technology

We are finding more and more that infrared helps to promote beneficial basking behaviours in our reptiles. Many keepers have presented anectodal evidence via our social media pages and positive reactions from the DHP. These include novel natural behaviours and improvements in the animals’ appetite, activity levels, and colouration.

There has been some very interesting work recently to show that infrared wavelengths and how they react to reptile skin. What has been shown is that the skin appears to retain heat better than inorganic objects. What this suggests is that once the wavelengths are absorbed by the skin and then changed to IR-C, (as happens with all objects heated by infrared-A and B) the skin partially blocks the wavelengths from going back out of the body4. Amazingly, this is exactly what happens within a greenhouse. We all know that glass rooms get warmer than those with brick or wooden walls, but have you ever thought about why? The infrared A and B can pass through the glass but then it is blocked on its way back out, until it has been converted to infrared-C, at which point it is released.4

This process is adopted not only by reptiles but also by other animals in order to retain heat. It is the specific design, at a microscopic level, of animals hairs that retain infrared and helps them to keep them warm.

Infrared wavelengths are also known to have beneficial effects on human and animal skin in other ways. It has been found that exposure to gentle infrared wavelengths in the morning actually protect the skin from the burning effects of UV rays later in the day. It has also long been known about the benefits of accelerated healing when a wound is exposed to infrared energy. This is now widely implemented for wound healing in veterinary medicine. A basking reptile will also benefit from this; along with the benefits of ultraviolet provision, the infrared will also help their skin recover from any injuries.

This rescue basilisk benefitted from use of the infrared heat, ample humidity and ultraviolet lighting and her damaged tail has now healed up perfectly.

You might be thinking that these wavelengths sound powerful and so could be dangerous. In fact the opposite is true. Because animals can recognise the heat as a more natural source, they are likely to better detect the heat, warm up more quickly and be able to get on with appetitive behaviours, therefore avoiding burns.

We do of course need to properly protect our animals in all cases; guard our lamps with a cage and check temperatures regularly using an infrared thermometer.

We have all seen those images of reptiles that have spent too long sitting on or under a heat source, only to become very burnt in certain areas. However, this almost always happens with unnatural heating methods or failure of the keeper to adequately protect their heat source. There could be two reasons for this. The first is that the animals cannot recognise the unnaturally balanced wavelengths of heat that are produced by certain traditional heat sources. Or, it could be that the animal is not getting a wide enough spread of heat to cover its whole body and so continues to bask even though certain parts of its body are overheating. Most likely it is a combination of the two. It can also be caused by an undersupply of ultraviolet energy, meaning that the animals overexpose themselves to high levels of heat in an effort to warm u[p sufficiently.

We can avoid this scenario by doing two things – ensuring a complete balance of wavelengths and also providing a wide basking area. Heat in the wild is not localised to a small spot – the sun’s energy comes down to the environment evenly. So, small heat lamps are not suitable for large animals because they do not heat the whole body.

How Should a Deep Heat Projector be Set Up?

This of course depends on the animal kept. For small animals, one DHP grouped closely with your T5 lighting will provide a good balance of wavelengths for them to bask.

If you have a large animal, such as a bosc monitor for example, you will want to ensure the heat spreads out over its body from at least the snout to vent. This may mean positioning the DHP higher up – photons spread out over distance; at 30cm away you will get a flood of heat around 40cm wide. However, using this method, you MAY find that you need an additional heat source in order to achieve the required temperature. You could group two heat projectors alongside each other, so the beams cross over and join together to create a wider basking zone. You could alternatively use a 100 or 150W Solar Basking Flood light to create a pool of visible light and UVA and then a DHP alongside it to complete the spectrum.

infrared, ceramic, ceramic heater, Deep Heat Projector
The bosc monitor is a large, highly energised species that may require two or more heat lamps.

Your linear UV-A + UV-B lamp should also be positioned so as to illuminate the basking area. Do this by placing it alongside the heat lamp and choose a lamp that is around 2 thirds of the enclosure’s length so that the captive environment has a gradient from warm, bright and drier, to cooler, dimmer and more humid. This is the basis of the light and shade method.

The Deep Heat Projector does not wastefully heat air like ceramics or tungsten lamps. It provides deep heat, much more effectively, deep into the dermis of an animal. Ambient heating is not as bioavailable to reptiles and amphibians as infrared energy.

The heat is absorbed into the rocks and logs where it is stored, released, reflected and refracted in a similar way as in the natural environment. It is the decoration that then heats the enclosure air temperature via IR-C convection. This is why the DHP does not get as hot, as quickly as other heat sources do. This means that the more natural decor we include under the lamp, the better the technology will work.

When using a DHP, we have to use a laser thermometer to measure the decoration around the animal and the animal itself at basking. It is best to place the probe under the basking zone – stick-on thermometers will not give an accurate reading of the energy that is available to your pet as they measure air temperature rather than available energy.

They can also take 2-5 days to burn in to full output and can take a while to release that energy if switched back off at night. The DHP will not disturb nightime cycles, so can be left on 24/7. A dimming thermostat is the best option for this lamp as it prolongs the lamps life and also allows the energy to increase and drop gently. If using a pulse or on-off thermostat, you will not get the full benefits of this heater.

Glossary of terms used: Infrared: forms of heat that are beyond the visible light spectrum
Infrared-A: the portion of energy that is closer to the visible spectrum (800 to 1400nm). Also called ‘near infrared’
Infrared-B: the portion of energy that is in the mid-range of infrared.
Terrestrial wavelengths: light (ultraviolet light, visible light & heat)
Infrared-C: far infrared – the furthest from the visible wavelengths, the non-solar infrared range.
Terrestrial wavelengths: light (ultraviolet light, visible light & heat)
Non-terrestrial wavelengths: light or heat that do not reach our environment from the sun. (UVC and IRC).
Non-terrestrial wavelengths: light or heat that do not reach our environment from the sun. (UVC and IRC).
Non-ionising radiation: radiation that has insufficient energy to completely remove electrons from atoms and molecules. Examples of this kind of radiation are visible light, infrared, microwaves and radio waves.
Basking: the way in which a reptile obtains energy from sunlight. It is the way in which they elevate their temperatute to be able to carry out biological processes and to allow them to convert the hormone D3 in their skin to the active form.

  The first in a series of four books exploring how reptiles interact with the natural environment; Fire: The Sun, Its Use and Replication within Reptile Keeping, will be out in October 2018.




References: Featured Image: Platysaurus intermedius, A. Jones
1. Barolet et al. (2016) Infrared & Skin, Friend or Foe? Journal of Photochemistry and Photobiology.
2,3. Copyright P. Butler, 2018
4. Rom Muryn pers. comm
5. Solar Radiation through the Living Body Walls of Vertebrates with Emphasis on Desert Reptiles, Solar Radiation through the Living Body Walls of Vertebrates with Emphasis on Desert Reptiles 1967.