Reptile Lighting

24 05 2011

Reptile Lighting

Many UVB lambs sold for use with reptiles are actually designed and manufactured for the tanning industry or for medical use.  Some especially powerful lamps are even used for industry purposes such as curing inks and paints.

Light is part of the electromagnetic spectrum which is actually a stream of energy or photons that moves in waves.  Long waves have a lower energy level while short waves have a higher energy.  The gap between the waves is called the wavelength of the light and is measured in nanometers (nm). Visible light for humans is wavelengths from 400 to 700 nm.  Many other animals including, including reptiles have vision that will extend into the ultraviolet or UVA light range.

UVA is an important component of sunlight and comprises wavelengths of light from 290 to 320 nm.  UVB rays (280 – 320 nm) are also found in natural sunlight but our atmosphere effective blocks wavelengths below 290 on the earth’s surface.  Depending on the animal’s natural habitat most UVB light from the sun is also filtered by the earth’s atmosphere with primarily only the longer-wavelengths getting through our atmosphere to any large extent. Atmospheric density does however change with the location on plant earth.  The atmosphere is thinner at higher altitudes than at sea level.  The same hold true for the equator than the poles of the earth.  UVB wavelengths of light will penetrate in greater amounts at higher altitudes and at the equator.  Reptile species native to high-altitudes and desert areas near the equator have adapted to the higher concentration of UVB light available by developing a thicker skin or having an internal black pigment around their body cavities to further protect their internal organs from the penetration of this wavelength of light.  May species of diurnal lizards which bask in sunlight will require and utilize this UVB radiation for the manufacture of active Vitamin D3.

UVC (180 – 280 nm) light is effectively filtered out by the earth’s atmosphere and will rarely reach the earth’s surface.  There are no animal species, including reptiles that are adapted to withstand any level of UVC light and should not be permitted in artificial lighting.

The easiest way to determine if a reptile needs UVB lighting is to look at their natural habitat and life history.  Those species that spend a significant amount of time basking in the sun typically need UVB.  Some species originating from desert habitats have the highest UVB requirements, while species that spend a large portion of their time under a tree canopy will have a lower requirement. UVB light will be blocked or filtered out by any glass or plastic separating the bulb housing from the enclosure.  Some fluorescent fixtures may come with a glass of plastic cover that should be removed if a fixture is being used in a herp enclosure.

To find out the amount of UVB lighting your reptiles are receiving a Solarmeter may be used.  The instrument should be held in the basking spot allowing the sensor to be at the level of the reptile’s back and aimed directly at the lamp being used.

Nocturnal lizards do not need UVB light, although some will require vitamin D supplementation.

All UVB-producing bulbs decrease their UVB output over time.  It is often important to provide a UV gradient where some portion of the cage should be without UV light so the animal can choose to move in and out of the light as their needs dictate.

Lower-wavelengths of UVB light are closer to UVC light which is more dangerous to the health of biological processes.  Even when used for very short periods UVC and lower-wavelength UVB light may have dangerous effects on biological processes.  These wavelengths of light may cause tanning to take place in minutes, rather than hours. Due to the power of these wavelengths of light they can be tolerated for only minutes rather than hours.

UVB-producing lamps that are sold for reptile use may produce significant amounts of the shorter-wavelength UVB than one would obtain under normal atmospheric conditions.  When used these lamps are likely to cause serious health problems in captive reptiles.  At the very least, we can expect eye damage.  In the more delicate species, such as chameleons or geckos, severe skin damage may be a result of their use.

Measurement of the total UVB output from a lamp does not provide sufficient information as to it’s efficacy for use in reptiles.  If most of the UVB light produced by a lamp is of the shorter wavelength then it will have a far greater effect on the reptile.

Linear Fluorescent bulbs may or may not emit UVB light.  These types of bulbs typically work well for enclosures housing animals that do not require UVB lighting and will not produce added heat.  Those fluorescent bulbs that do produce UVB wavelengths will only penetrate 10 to 12 inches within the herp enclosure.

Compact fluorescent bulbs work well for small enclosures and may be found in UVB producing and non-UVB models.  These bulbs do not produce a lot of excess heat.

Mercury Vapor bulbs do produce UVB rays and may produce large quantities of extra heat.  The UVB radiation produced by these lamps will penetrate up to a depth of 3 feet in a focused area.  These bulbs may be ideal for those herps requiring large amounts of UVB but may be excessive for those herps having a lower UVB requirement.  Safe basking distances should be determined before using these bulbs.

Red light may be used for night viewing.  Reptiles do not see light in the red end of the color spectrum allowing them to be viewed at night without disturbing them.


Coote, Jon.  “Dangerous Rays.”  Pet Business.  January 2008. Pp. 68-71.

Spiess, Petra.  “Light Up Your Herps.”  Pet Product News International.  May 2007. Pp 92-93.




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