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.