One of the most confusing and intimidating components of tortoise husbandry is lighting. Many new keepers don’t understand the lighting needs of their animals or how to provide the kind of lighting they need to remain healthy.
But don’t worry. I’m about to explain everything you need to know about setting up the lights in your tortoise’s enclosure.
You’ll learn exactly what you need to do to provide the right amount of light for your tortoise, and discover that it’s actually simpler than you may think.
Lighting Needs for Tortoises
Like many diurnal (day active) reptiles, tortoises need access to “full spectrum” light. This simply means that your pet needs light that not only contains the visible wavelengths (what humans think of as “light”) but also wavelengths in the UVA and UVB portions of the spectrum.
Visible light provides the same basic function for tortoises that it does people: It allows them to see their surroundings and navigate through the environment. But UVA and UVB light play other roles in the health and well-being of tortoises.
UVA light is thought to be visible to tortoises, and it helps them to recognize food. It is also likely to provide psychological benefits and help them to maintain proper circadian rhythms. UVB wavelengths, on the other hand, help tortoises synthesize vitamin D3. This, in turn, allows them to properly utilize the calcium they obtain in their diet.
When deprived of UVB light, tortoises can develop metabolic bone disease, which can manifest in limb deformities, soft jaw bones, and malformed or weak shells. Unfortunately, the damage caused by metabolic bone disease appears to be irreversible, which highlights the importance of providing your tortoise with proper lighting from the outset.
Lighting Equipment: Selecting the Best Lights for Your Situation
In the wild, tortoises are able to obtain all three types of light – visible, UVA, and UVB – from sunlight. Similarly, most tortoises reared outdoors are also able to obtain all of the light they require from the sun, meaning that they don’t require any supplemental lighting (this is not necessarily true for keepers located at northern latitudes, so be sure to check with your veterinarian in these situations).
However, tortoises reared in indoor enclosures cannot satisfy their lighting needs in this way. Even if the tortoises can access sunlight through a window, the glass will filter out the UVB light, placing them at risk.
Instead, tortoises need specialized lighting to remain healthy when maintained indoors. There are essentially four different options available:
- Mercury Vapor Bulbs: Mercury vapor bulbs are often the most expensive of the three options (though this varies, based on a variety of factors), but they also produce a great deal of heat. This is convenient, as it allows many keepers to satisfy their pet’s lighting and heating needs with one light.
- Full-Spectrum Fluorescent Tubes: Often the most affordable choice, fluorescent bulbs have been used by tortoise keepers for longer than either of the other options. These types of lights do not produce much heat, so you’ll still need to utilize separate heating devices. Additionally, these types of lights require ballasts, which increases your overall investment.
- Full-Spectrum LED Lights: The newest of the three basic options, LED lights are quickly growing in popularity. They rarely produce much heat, so you’ll still need to employ separate heating devices. However, they often screw into standard light sockets (unlike long fluorescent tubes), alleviating the need for costly fixtures. They are also easier to fit into small spaces and usually produce a very pleasing light.
- Compact Fluorescent Bulbs: These types of lights offer some of the benefits of LED lights (they’re small and easy to fit into tight spaces), but they’re typically affordable and don’t require special ballasts. However, like standard fluorescent tubes and LED lights, they don’t produce heat. So, you’ll still need separate heating devices for your pet.
Note that there is considerable variation between specific products. Accordingly, you’ll need to think carefully about your tortoise’s needs and your specific situation before making a purchase.
It is also important to note that different tortoise species require different amounts of UVB light. Broadly speaking, those species hailing from deserts require lights that produce more UVB rays than those hailing from forested habitats.
Tortoise Enclosure Lights Set Up
No matter which kind of lights you choose, you’ll need to set them up in an appropriate manner. This generally means doing the following:
- Install the necessary fixtures. Different kinds of full-spectrum lights require different types of fixtures. However, most will either require standard heat-lamp-style receptacles or fluorescent ballasts (note that many are sold as combination packs, containing the fixture and the light). Consult the manufacturer’s instructions to determine the best way to connect the fixtures to the enclosure.
- Place most of the full-spectrum lights near the heating devices. This won’t matter if you’re using mercury vapor bulbs, as they’ll create the light and heat required for a suitable “basking spot.” However, if you’re using any of the other three types of lights, you’ll want to locate them close to the heating devices you use in the habitat.
- Consider placing additional full-spectrum lights away from the basking spot. This is only necessary for very large enclosures, but it can help encourage the tortoise to use a greater percentage of the available enclosure space.
- Be sure to include shaded portions within the enclosure. You do not want to force your tortoise to be exposed to UVA or UVB light at all times. Accordingly, you’ll want to incorporate hides or barriers that provide shaded areas within the habitat.
- Ensure that your tortoise can get close enough to the lights. The amount of UVA and UVB emitted by the lights will fall with increasing distance, rendering them less effective. Consult the instructions provided with your lights to determine how close they need to be to the top of your tortoise’s shell (generally, between 6 and 18 inches).
- Monitor the amount of UVA and UVB light produced by the lights. It is always a good idea to monitor your lights to ensure they’re producing full-spectrum light. You obviously can’t see UVA or UVB light, so you would never know if you received defective lights (until your tortoise started displaying signs of illness). There are light-sensitive cards available, which can tell you if your lights are producing UVA and UVB light. However, it’s worth investing in an index meter, which will provide more detailed information and help you get the right amount of light to your pet.
Light Operation, Maintenance, and Replacement
Understand that your job is not finished once the lights have been installed. You’ll still need to do a few more things, including:
- Connect the lights to a timing device. It is important that your tortoise can enjoy a consistent day-night schedule, known as a photoperiod. Some keepers try to do so by manually turning the lights on and off each day, but mistakes are invariably made. So, simply purchase and use a timing device to automate the process.
- Replace the lights as recommended by the manufacturer. All full-spectrum lights begin producing less UVA and UVB light over time, so you’ll need to replace them periodically. The manufacturer will indicate an appropriate replacement schedule (typically every 6 to 12 months) in the product instructions. Just keep in mind that these are maximum lifespans; it is always wise to replace them more frequently than suggested.
- Dispose of old or broken lights properly. Many full-spectrum lights contain mercury or other toxic substances. As such, they shouldn’t be discarded with typical household garbage. Consult the manufacturer’s recommendations as well as your local environmental authorities to learn the proper disposal procedure for your chosen type of light. Additionally, you’ll need to use care as broken glass can lead to injuries.
A Hybrid Approach: Lights and Outdoor Access
It is important to note that while proper full-spectrum enclosure lighting has been shown to be sufficient for keeping tortoises healthy, no commercially manufactured light will ever be able to produce light equivalent to that produced by the sun.
Accordingly, many keepers who’re not willing or able to rear their tortoises outdoors all year long employ a hybrid approach. Specifically, they’ll keep their tortoise indoors, in an enclosure that features full-spectrum lights for some portion of the year, and then move them outdoors for short periods of time when it is possible to do so.
For example, keepers living in areas with cold winters may maintain their pets outdoors during the late spring, summer, and early fall, and then move them to indoor enclosures (with full-spectrum lights) for the rest of the year. Alternatively, keepers may simply maintain their tortoises indoors for most of the time, and then provide outdoor access for brief periods when circumstances allow (such as weekends).
This approach is more labor-intensive, but it allows you to give your tortoise the best of both worlds. It also allows you to take advantage of natural sunlight and save on electricity costs when possible.
Citations
- Arizona Exotic Animal Hospital – Basic Care: Sulcata Tortoise
- Reptile UV Info – Disposing of Mercury Lamps
- U.S. Environmental Protection Agency – Recycling and Disposal of CFLs and Other Bulbs
