Corn snake or Pantherophis guttatus

For most of my employees, longtime hobbyists and herp enthusiasts all, the dilemma of proper lighting for exotics is a confusing and daunting snarl of competing products and information.

Imagine, then, how confusing this must be for your average customer! Let’s try to straighten some of this out.

First of all, “lighting” and “heating” a cage are separate but intertwined issues. You can use lights to heat a cage…but you can also use ceramic heaters or heat pads that emit no light. You can light a cage with bulbs that, ironically, produce no heat. Almost all reptiles and amphibians require some form of heat, but many of them require not a bit of light. Confused yet?

So, for the purposes of this article, let’s just set heating apart and talk purely about the lighting requirements of our little friends. 


Focusing on UVB

The main point of using specialized lights in cages is to provide Ultraviolet B Light (UVB) (not UVA, bands of which occur with just about all lights, and are misleadingly touted on the packages of many herp-related products). Intense UVB comes from sunlight and is used by animals to process vitamin D3. It also, and to my mind more importantly, is the main spectrum of light that herptiles see; without it they exist in a visual haze. We cannot see UVB at all, but to herps it is the primary light.

For animals that bask, UVB is absolutely essential. For those that don’t bask, it can still be important. UVB is most commonly available as florescent bulbs (the long bulbs you pop in to fixture), and those are generally the best way to go. There are also florescent bulbs available on the market today that can be used with an incandescent (screw-in) fixture, but they have limited usage.

Imagine you are in a room with no lights, no windows, and a closed door. The only light coming in is a shaft of sunlight coming though a hole in the roof. Is that a well-lit room? Obviously not. The idea with UVB bulbs is to have the light spread through as much of the enclosure as possible, and a flo fixture can do just that. The incandescent-style bulb is useful only in an arboreal cage with a very small footprint. In such a cage, there is little need for the light to spread.

There are also bulbs that provide heat and UVB in one bulb. That would seem to be convenient, right? But these bulbs still have the issue of not spreading the light, and are pretty much the most expensive bulbs on the market. They tend to have a lifespan akin to most incandescents. Flo bulbs rarely burn out, and in fact, the UVB will be long gone by the time the bulb does go (and because of that, they should be replaced once a year, whether they look like they need replacing or not). So the customer is paying a premium for a bulb that does not spread light sufficiently and burns out quickly. And that’s called a rip-off.

As I mentioned above, some animals do not seem to need UVB at all. Most herps, whose diets are largely rodent-based, including almost all snakes, seem fine without it (the exceptions being tree snakes like Tree Pythons, Emerald Boas, etc.). On the other hand, most insectivores and vegetarians seem to need it. Even many nocturnal reptiles will show remarkably better health with it! For instance, nocturnal geckos like Leopards and Cresteds will sleep in broad daylight, soaking up the UVB and as a result producing more and better eggs and offspring.

Even some amphibians have been shown to do better with it! Spotted Salamanders and Dart Frogs have shown significant basking behaviors under it.


Finding the Right Light

Now, UVB bulbs tend to come in two strengths: 5.0 and 10.0. Which one is appropriate? It depends on what we’re lighting. In general: desert lizards and tortoises want 10.0, as do equatorial animals with significant sunlight exposure. Deep forest animals whose exposure is more along the lines of dappled sunlight, and temperate animals will be happier with 5.0. If in doubt, contact the bulb’s manufacturer and ask their advice. Be careful; 10.0 can actually do retinal damage to some herps.

For many years, flo bulbs came in T12 (1.5 in.) diameters. Those are now antiques. Manufacturers switched to T8 (1 in.), which are still commonplace, but due to environmental concerns, they too are on the march to extinction. The up and coming bulb is the T5 (5/8 in.), and in the past few years we have seen this bulb taking over the marketplace. This is good news; they produce a demonstrably better light for human perception and the beauty of our displays. Oddly, the only major company I know of who has really embraced this inevitable evolution is Zoo Med, who produces an excellent series of T5 fixtures. They have become an essential part of many of our animal/set-up sales.

Unfortunately, due to the potential risk of 10.0 overexposure described above, their fixtures only come with a 5.0 bulb, meaning that some customers have to buy a fixture and immediately switch to the stronger bulb. C’est la vie!

Another word of light-related warning: if you happen to live in a part of the country that affords you the opportunity to allow your animals to spend a lot of time outdoors in real sunlight, this will dramatically affect both your use of cage lighting and your use of vitamins and calcium. Outdoor exposure will allow your animal to biochemically produce enough D3 to make necessary a switch to D3 reduced calcium and/or reduced strength UVB bulbs.

With UVB taken care of, let’s briefly discuss the various options available for heat lights. Firstly, you’ll almost always want to use spotlights, as opposed to household bulbs. Spots produce a directed heat, whereas standard bulbs diffuse the heat. You want the variation in temperatures that spots allow. 

In almost all cases, given that a pet has a hide space, it will adapt to whatever color bulb you prefer, be it red, white, or violet. Don’t swerve your customers into thinking they need multiple bulbs; inevitably they will discover that’s not true and it will make you look either ignorant or dishonest. Neither is a good look.

There is one more bulb type currently on the market that I believe to be a scam: the LED. LED produces no useful UVB; it also produces no heat. I have asked a company rep why I should carry them at all, and he struggled with the answer. After squirming a bit, he said, “Well, they’re really good for plants, and they make tanks look good!”

In other words, they don’t do a thing for the animals. I don’t carry them, and if you do, in the end, you’re just going to make your competition look good. Don’t get LED down a fool’s path!  PB


Owen Maercks has enjoyed being immersed in the world of professional herpetoculture for nearly 40 years. His store, the East Bay Vivarium in Berkeley, Calif., is one of the oldest and largest herptile specialty stores in the U.S.