Understanding UV Light and Infrared in Reptile Husbandry | UVA/UVB/UVC & IRA/IRC

UV Light and Infrared in Reptile Husbandry: A Breakdown of UVA, UVB, UVC, and Infrared Radiation (IRA/IRC)

Reptile husbandry involves replicating the conditions of the reptiles' natural habitats as closely as possible, which includes providing proper lighting. Lighting plays an essential role in a reptile’s health, behavior, and overall well-being. Among the most critical factors to consider when setting up a reptile enclosure are UV light and infrared radiation. Understanding the elements of light and how they affect reptiles can help you create a more conducive environment for your pet, ensuring they live a healthier, happier life.

UV Light: UVA, UVB, and UVC

Ultraviolet light (UV light) is a type of electromagnetic radiation with wavelengths shorter than visible light but longer than X-rays. Though UV rays are not in our visible light spectrum, reptiles can see UV! UV light is crucial for reptiles as it influences their physiological processes, particularly those involved in metabolism, immune function, and vitamin synthesis. Some, but not all, reptiles require UV lighting to survive. Though some reptiles can survive without access to UV lighting, it is recommended to provide all reptiles with access to species appropriate levels of UV lighting due to the psychological benefits and to closer replicate their natural environment.

The three main categories of UV light are UVA, UVB, and UVC, and each plays a different role in reptile husbandry.

UVA: The Visual and Behavioral Influence

• Wavelength: 320–400 nm
• Role in Reptile Health: UVA light has a significant impact on reptile behavior, particularly in terms of communication, territoriality, and mating rituals. Reptiles can see UVA light, which helps them distinguish between objects and signals to other reptiles about territory or reproductive status. While UVA does not directly contribute to vitamin D3 synthesis, it affects the reptile's natural behaviors, such as basking, which indirectly influences their overall health.
• Practical Application: UVA light is important for the mental and social well-being of reptiles, especially for species that rely on visual cues for mating or social behavior. UVA is generally emitted by all types of UVB reptile bulbs. 

UVB: Vitamin D3 Synthesis and Calcium Metabolism

• Wavelength: 290–320 nm
• Role in Reptile Health: UVB light is perhaps the most critical form of UV radiation for reptiles because it enables them to synthesize vitamin D3. Vitamin D3 is essential for the absorption of calcium from the diet, and without sufficient UVB exposure, reptiles can suffer from metabolic bone disease (MBD), a common and serious condition that weakens bones as their bodies pull nutrients from them to support other vital body processes and can lead to deformities, paralysis, or even death.
• Practical Application: Many reptiles need exposure to UVB light for at least a portion of the day to ensure proper vitamin D3 synthesis. Special UVB bulbs are designed for reptiles to emit the correct wavelengths, and it’s crucial to choose a bulb with an appropriate UVB output for the species of reptile you are caring for. For example, desert-dwelling reptiles (like bearded dragons) that bask in full open sunlight in the wild require higher UVB intensity, while forest-dwelling reptiles (like chameleons) need a lower intensity bulb. Distance from the bulb to the animal, the type of bulb reflector, bulb strength, whether the bulb is mounted above or below the screen, screen density, brand of bulb, and bulb age all play a role in how much UVB your reptile is receiving. UV that is too intense can lead to burns and blindness, while UV that is not strong enough can cause previously mentioned health issues over time. 

Overwhelmed? We can help! Check out our UVB Calculator to get a good starting place for the proper bulb strength and distance for your reptile! 

UVC: The Harmful Wavelength

• Wavelength: 100–290 nm
• Role in Reptile Health: UVC light is the shortest and most dangerous type of UV radiation. Fortunately, it is mostly absorbed by the Earth’s atmosphere and does not reach the surface in significant amounts. However, when UVC light is emitted from artificial sources (like certain fluorescent bulbs or mercury vapor bulbs), it can be harmful to reptiles, causing eye damage, skin burns, or other injuries.
• Practical Application: Most reptile-specific bulbs do not emit high levels of UVC radiation; however, it’s essential to be cautious when selecting light bulbs and to ensure that the bulbs in use do not emit dangerous levels of UVC. Never buy cheap unbranded UVB bulbs or from brands that are not well known in the industry; Always go for brands consistently producing high quality, trustworthy products such as Arcadia and ZooMed. The price of the bulb is worth it to keep your pet safe and avoid serious health risks. Always follow manufacturer guidelines and maintain a safe distance between the light and the reptile.

Infrared Radiation (IRA/IRC) and its Importance in Reptile Husbandry

Infrared radiation (IR) is a form of heat radiation with wavelengths longer than visible light, typically divided into two categories: Infrared A (IRA) and Infrared C (IRC). These types of infrared light play a crucial role in regulating the temperature within the reptile's habitat.

Infrared A (IRA): Deep Heat Penetration

• Wavelength: 700–1400 nm
• Role in Reptile Health: Infrared A (IRA) heat penetrates the reptile’s body, warming up deeper tissues, which is particularly beneficial for thermoregulation and metabolism. IRA is useful for maintaining a warm environment in enclosures where heat is necessary for digestion and overall bodily function. IRA is the most deeply penetrating, natural form of heat that we can offer our reptiles.
• Practical Application: For many reptiles, maintaining a specific thermal gradient (from cooler to warmer areas within the enclosure) is essential for species such as snakes, lizards, and tortoises that rely on external heat sources to maintain their internal body temperature. Overhead heat lamps that emit visible light give off IRA that heats the surrounding enclosure, but not all bulbs are created equally. Halogen bulbs are the most natural form of heat that we can offer our reptiles, as they give off the highest levels of IRA. 

Infrared C (IRC): Surface Heating

• Wavelength: 1400–3000 nm
• Role in Reptile Health: Infrared C (IRC) is a type of infrared radiation that heats the surfaces of the enclosure and the reptiles themselves. This heat is typically felt on the skin's surface, promoting surface-level warmth, which is especially helpful for reptiles that bask and receive belly heat (for example, in basking areas). Heat bulbs that emit IRA will also emit IRC as the light is absorbed into the surface and turned from IRA to IRC. 
• Practical Application: IRC is often produced by ceramic heat emitters and heat mats. These types of heating elements can help provide localized heat for warm hides and can be used in conjunction with other temperature-regulating equipment to ensure a full thermal gradient in the enclosure. IRC can be beneficial for reptiles that require constant access to low levels of heat, such as crepuscular or nocturnal species that may not partake in midday basking in the sun’s intense rays like their diurnal counterparts.

Since IRC only heats the surface, it is not an effective measure of raising ambient enclosure temperatures, instead it is more ideal for creating localized thermal gradients or used in conjunction with a heating element that emits IRA to create a more intense basking spot.

Safety with Heat

All heating elements regardless of brand or type should be hooked to a thermostat to monitor and regulate the temperature to ensure safe operation and prevent overheating and burns. 

Practical Tips for Reptile Lighting and Heat Setup

1. Understand Your Species' Needs: Different reptiles will have vastly different UV and heat requirements. For example, some desert species need intense UVB and high basking temperatures, while some tropical species need more moderate UVB and a stable, temperate environment. Offering a gradient within their habitat of exposure levels is vital so your reptile can escape from higher temperatures and UV exposure.
2. Use Proper UVB Bulbs: Make sure to select UVB bulbs with the correct output for your reptile's specific needs. UVB intensity decreases with distance, so position the light at an appropriate distance from the top of your reptile’s back.
   Use our helpful UVB Calculator to get a good idea of strength and distance required for your species.
3. Create a Thermal Gradient: Provide a range of temperatures in the enclosure. Include a basking spot with higher temperatures (ideally using overhead bulbs that give off IRA for basking species), and regulated heat mats (that utilize IRC) to warm localized areas for animals with less intense heat requirements,  and be sure to incorporate cooler areas for the reptile to retreat to when necessary.
4. Regular Bulb Replacement: UVB bulbs lose their effectiveness over time, even if they still emit visible light. Replace UVB bulbs every 6-12 months, depending on the bulb type and the manufacturer's recommendations. Purchasing a Solarmeter 6.5 is an investment that will save you money in the long run and give peace of mind that your reptile is receiving the correct UV exposure at their basking area, and that your UVB bulb is still emitting effective levels of UVB for your species over time. You will find that many times the bulbs can last beyond the 6-12 month recommended replacement timeline, but without a Solarmeter to check output, replacing on a schedule is necessary.
5. Monitor Temperature and Humidity: Keep track of both the temperature and humidity levels in the enclosure to ensure your reptile’s environment is optimal. Use digital thermometers and hygrometers along with hooking all heating elements to dimmers/thermostats to maintain accurate readings and safe levels of heat.

Proper lighting and heat are vital components in reptile husbandry. Providing UVA, UVB, and infrared radiation (IRA/IRC) all contribute to the well-being of reptiles in captivity, influencing their behavior, metabolism, and physical health. UVA enhances behavior and visual functions, UVB is essential for vitamin D3 synthesis and calcium metabolism, and infrared radiation plays a key role in temperature regulation. Understanding the differences between these light types and how they impact your pet’s needs will help you create a healthier and more naturalistic environment, ensuring your reptile thrives in captivity!