Home | General Reptile & Amphibian Articles | Providing Ultraviolet A Light (UVA) to Reptiles and Amphibians – Part 1

Providing Ultraviolet A Light (UVA) to Reptiles and Amphibians – Part 1

While the role of UVB light in the care of reptiles is well understood, we are only beginning to learn about their needs for UVA. Unlike UVB, UVA may also be critical to the proper husbandry of amphibians and invertebrates. Today I’ll summarize what is known; in Part II of this article we’ll take a look at some of the UVA-Emitting Bulbs currently available at ThatFishPlace/ThatPetPlace.


UVA light has a wavelength of 320-400 nanometers (a nanometer measures 1 thousandth of 1 millionth of a meter…don’t ask me how that was figured out!) and is visible to herps and many invertebrates, but not to people.

The Pineal Gland

UVA light sensed by an organ known as the pineal gland (located near the brain) of many reptiles.  It functions in the regulation of their “internal clocks” or circadian rhythms, and is believed responsible for daily and seasonal behavioral changes in response to varying light levels.  A similar process is at work in amphibians and at least some invertebrates.

Uses in Captivity

The provision of UVA light encourages natural behavior, better appetites, basking and breeding in a great many species.  UVA reflective areas on animals and plants (which we cannot see) help a variety of creatures to identify mates, food and predators.

A lack of UVA may be responsible for the failure of many otherwise hardy species to breed regularly in captivity.  For example, without UVA light, female desert iguanas cannot see the pheromone trails laid down by males in breeding condition, and hence may fail to reproduce.

Unlike UVB, which is generally not essential to nocturnal animals, UVA light may have a role in regulating the behavior of both diurnal and nocturnal species.

Next time we’ll take a look at some UVA-emitting bulbs.  We have a great deal to learn about UVA.


  1. avatar

    Recently I’ve seen a lot of talk about how there are possible, if not certain, positive effects on leopard geckos (nocturnal reptiles) on uvb. I’ve seen posts and surveys done that argue leopard geckos absorb uvb for the benefit of their health. I’ve never had a problem getting uvb for my leos. For the past 6 months I’ve had my leos on desert-type fluorescent bulbs (Zilla 50 series). They’re the same ones I have for my bearded dragon. I love them because all of my reptiles under them have been healthy. Therefore, I see no reason why nocturnal reptiles shouldn’t be on uvb. I don’t know, however, if they should be exposed to MVBs.

    • avatar

      Thanks for bringing up this interesting point. UVB will in all likelihood do no harm to leopard geckos. I would, however, be sure to provide shelters so that they can avoid the light – treefrogs kept under UVB often develop corneal opacities and other eye problems if not provided with shade/cover. The eyes of nocturnal creatures may sensitive to UVB, but we have not yet established that, other than by casual observation.

      The reason we don’t generally suggest UVB for leopard geckos is that research and practical experience has shown that, like snakes, highly aquatic turtles and some other reptiles, they are able to utilize dietary Vitamin D3, and need not produce it in their skin in the presence of UVB. However, a naturalistic light cycle of any type is helpful, and perhaps, like people, they can utilize 2 methods of Vitamin D3 synthesis.

      Bearded dragons and other diurnal lizards benefit from the provision of UVA as well as UVB. It seems not to be critical for their survival, but an important element in breeding and promoting natural behaviors. It also seems to improve the appetites of certain desert-adapted reptiles.

      Good luck and thanks again for your thoughts; please keep me posted.

      Best regards, Frank Indiviglio.

About Frank Indiviglio

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Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.
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