Reptiles and amphibians are ectotherms, meaning they rely on their environment for bodily warmth. While mammals produce their own body heat, herps must move into warmer or cooler areas within their habitat to maintain a healthy internal body temperature. This target temperature is typically based on species, habitat and the current physiological needs of the animal.
In the wild, herps are able to bask directly in the sun for as long as needed to achieve an adequate body temperature. In addition to thermal energy, the sun also produces high levels of ultraviolet radiation that many herp species use for specific physiological functions. When herps are kept indoors under artificial conditions as pets, breeding stock or as part of species conservation efforts, the heat and light normally provided by the sun must be replicated to the best of the keeper’s ability.
While there is simply no replacing the sun itself, the market offers a myriad of products designed to provide pet herps with the beneficial heat and full-spectrum lighting that they require for long-term health.
Some Like it Hot
The needs of each reptile species are unique when it comes to heating and lighting. That said, some generalizations can be made regarding the manner in which the heat is provided. A primary heat source is meant to provide a stable background temperature within the herp’s environment. Secondary heat sources are typically used to provide elevated basking temps, high daytime temps and, most importantly, a thermal gradient within the habitat ranging from cool to hot.
The types of heating devices used varies widely based upon species, enclosure type and size, household temperature and time of year. Standard filament light bulbs have long been used to provide heat to reptiles. These bulbs are available in a wide range of wattages, shapes and colors.
Bulbs that produce bright, white light are best used during the day, while purple or red bulbs are ideal for providing heat at night. Most reptiles do not respond to the reddish glow produced by these bulbs, and some theorize that they cannot see it at all. These bulbs can provide a constant or nocturnal source of heat that will not interfere with the natural photoperiod of the animal.
When heat is desired without any visible light, the use of undertank heat pads is recommended. They are usually located underneath one end of the terrarium and provide radiant heat through the enclosure floor and bedding. Thermostats or rheostats can be used in conjunction with these devices to control heat output.
If more heat is required than a heat pad can provide, ceramic heat emitters are an ideal choice as both a primary or secondary heat source. These porcelain units are shaped similarly to a light bulb and have the same screw-type base, but they don’t provide light. Another advantage is that these heaters have no internal filament to break or burn out. As a result, these heaters last a very long time with proper use.
Light the Way
There is much more to providing light than pulling a 60-watt bulb from your favorite reading lamp and setting it above a terrarium. It is crucial that owners understand the levels of ultraviolet light herps require, specifically UVA and UVB, as well as the duration of the day/night cycle known as the photoperiod.
Ultraviolet light is vital to the health and well-being of most diurnal reptiles and amphibians. The type of herp, as well as the habitat from which it comes, both help dictate the type and amount of UV lighting that is needed. Most lizards, turtles and tortoises are highly sensitive to UVB lighting, the specific wavelength of light that aids in production of vitamin D3 in the animal and subsequent calcium absorption in the gut.
When direct natural sunlight is not a feasible option, bulbs designed specifically to replicate the sun are required. Traditionally these bulbs were available in the form of a standard linear fluorescent bulb. These bulbs are constructed with special glass and have certain phosphors added that greatly differentiate them from any ordinary fluorescent bulb.
When used for 10 to 12 hours a day, along with proper heat, these bulbs are a boost to the psychological well-being of the animal. They also play an important role in calcium absorption. These linear fluorescent bulbs are available from many top manufacturers in a variety of strengths or intensities. The values are depicted as numbers such as 2.0, 5.0, 8.0 or even 10.0, which all correlate to the percentage of total light emitted from the bulb that is within the UVB range.
Generally, bulbs producing two percent or less UVB are recommended for amphibians, snakes, nocturnal herps or other animals that rarely bask in the sun. Bulbs in this UVB range also tend to have a higher visible light output, making them ideal for living plants within naturalistic vivaria.
Bulbs in the five-percent range are typically recommended for basking tropical species such as green iguanas, anoles and most aquatic turtles. Higher output UVB tubes in the eight-percent-or-higher range are most effective for sun-loving desert species (bearded dragons, uromastyx and most tortoises), as well as for use in very large or tall enclosures, or when mesh screen lids are used.
Linear fluorescents are available in a variety of standard sizes ranging from 15 to 48 inches. These bulbs fit into standard hood-type fixtures such as those used with fish aquariums. Some higher-end fixtures designed specifically for UVB bulbs are equipped with highly polished aluminum reflectors, assuring that ample light is directed downward into the habitat.
Among the newest trends in UV lighting are compact fluorescent lights (CFL), which resemble the energy-saving spiral bulbs that screw into a standard screw-in type fixture. These bulbs are available in a variety of intensities, much like those of linear bulbs: 2.0, 5.0, 8.0, and 10.0 strengths are among the most readily available and popular models. It is still, however, best suited for use in smaller terrariums or as a supplement to another bulb. Larger environments are more efficiently illuminated with the use of a linear bulb that spans the entire length of the enclosure.
One of most exciting advances in reptile heating and lighting has hit the U.S. market in just the past 10 years. Self-ballasted mercury vapor bulbs are now widely available and can be used as a source of both heat and UVB, all in one bulb. These bulbs are convenient for many keepers, and it should be noted that the amount of UVA and UVB emitted by these lamps far exceeds that of any type of fluorescent.
As a result of the high heat and UVB levels that these bulbs produce, they should be reserved for use in large enclosures or with animals with very high UV requirements. These bulbs have even been used therapeutically with ailing herps that were previously deprived of adequate UV light and calcium supplementation.
Jonathan Rheins is an avid herpeteculturist whose interest in all things reptilian began at an early age. He is a manager at LLLReptile & Supply Co. in Escondido, Calif. and, when not fulfilling that position, spends his time working with and writing about a wide variety of exotic reptiles, amphibians and invertebrates.