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[NicoleRussell]

(Written by Robert MacCargar)

Iguanas and Artificial Ultraviolet Light:
How and How Much Made Simple — Well, Not Exactly Simple…

This article was originally published in the International Iguana Societies magazine “Iguana” and was edited by Dr. Robert Powell and A.J. Gutmann (Volume 10, No3 September 2003) and later published in the Upstatate Herpetological Association news letter Volume#15, issue#5 “HerpBeat” .

Dr. William Gehrmann kindly reedited the paragraph concerning the biological process of D3 conversion (his editing is in bold print). It has again taken another reediting to reflect the latest research by Dr Gehrmann and his associates published in the Journal of Herpetological Medicine and Surgery Volume 13, No.2, 2003.


Bob MacCargar

Readers will recognize that, in order to stay healthy, iguanas require UV-B (ultraviolet radiation in the “B” range) as much as they need the complex salads we prepare for them daily. Without UV-B, the all-important mineral, calcium, cannot be effectively absorbed — and calcium is as critical as nutritious food, water, and heat. In responsible husbandry, we must replicate the UV spectrum required for the photochemical process involved in metabolizing vitamin D3 (which mediates calcium absorption) — while never forgetting that this will be of little importance if the diet, heat, etc. are less than optimal. Also remember that this is a discussion on what is best for reptiles, NOT humans. We have deliberately excluded highly technical terms to keep the reading enjoyable.


UV-B is part of the electromagnetic spectrum. This spectrum includes everything from radio waves at one end to gamma rays on the other. All of the EMS is called “radiation”. Visible light is somewhere in the middle. Wavelengths are read in nanometers from 0.001 nm (x-rays) to 100 billion nm (radio waves). A reptile bulb can be subjected to testing by an ultraviolet radiometer and spectrographs in order to measure precisely the wavelengths that are being produced. There are no longer unknowns in the electromagnetic spectrum.