Zoo Med NatureSun® - Manual (Page 5)

Fluorescent lamps that
provide UVB, UVA and
human-visible light.
Courtesy Shane Bagnall
fat soluble and carries a risk of overdose, as do all
fat-soluble vitamins.
In addition to being a major component
of bones and eggshells, calcium is involved in
countless biological processes at the cellular
level, including cell communication, muscle
contractions and other functions that are
essential to life. Vitamin D3 is responsible for
calcium metabolism, and if there is not enough
circulating vitamin D3 in the blood, animals
are not able to use the calcium in their gut
that they get from their food. Dietary calcium
would then pass through the gut unused, and
animals would be forced to take it from their
bones, ultimately leading to a form of metabolic
bone disease known as nutritional secondary
hyperparathyroidism.
Animals can get vitamin D from two
different sources: UVB-induced synthesis in
the skin, or by ingesting vitamin D in the food
that they eat. The livers
of vertebrate prey, for
instance, such as mice,
rats and cod, provide a
rich source of vitamin
D3. Researchers have
found, however, that
not all reptiles and
amphibians are able to
adequately use dietary
vitamin D3, and they
depend on UVB-induced
synthesis of vitamin
D in the skin. Some of
the reptiles for which
this has been shown
to be the case include
Seen here is a Gooch
& Housego model
OL-756 scanning double-
grating monochromator
spectroradiometer (left)
alongside a Solartech
model 6.2 UV-B Solarmeter
digital ultraviolet
radiometer (right). Both
are used to measure light.
Courtesy John C. Dowdy
Reptiles | 5