Geckos are fascinating reptiles that have the ability to change colour. This colour changing ability, known as metachrosis, helps geckos camouflage and communicate. But why exactly do geckos change colour? There are a few key reasons.
Temperature regulation
One of the main reasons geckos change colour is to regulate their body temperature. Geckos are ectothermic, meaning they rely on external sources to regulate their body temperature. Lighter colours reflect more sunlight and keep the gecko cooler, while darker colours absorb more sunlight and warmth. This allows geckos to warm up or cool down by changing to lighter or darker skin tones.
Most geckos darken during cooler temperatures and lighten during warmer temps. This helps them maintain their preferred body temperature. A gecko’s ability to alter its skin colour to regulate temperature is called thermoregulation. It allows geckos to be active during cooler times when other reptiles may be inactive.
Camouflage
The chameleon-like colour changing ability of geckos also assists with camouflage and hiding from predators or prey. Geckos can shift skin colour and pattern to better match their surroundings and avoid detection. Some species, like the moorish gecko, can even change from drab brown to bright green in a matter of seconds when disturbed!
This rapid colour change startles predators while also helping the gecko vanish against leafy or grassy backgrounds. Geckos that rest on tree trunks are also known to darken their skin to better blend into the bark. By matching its skin tone and pattern to the environment, a gecko can easily escape threats through camouflage.
Communication
Geckos also utilize colour changing abilities to communicate with each other. Bright colours and patterns are used to attract mates, warn off competing males, or signal danger. For example, when defending territory male geckos often become brighter in colour, flashing vibrant reds, oranges, blues, and greens.
Females also exhibit more muted colouring when gravid (carrying eggs). The differences in colour help geckos relay important social information to others of the same species. Specific skin tone changes can send a clear message without making a sound.
Why can geckos change colour?
So how exactly are geckos physically able to change their skin colour? It comes down to special pigment cells called chromatophores found in their skin.
There are 3 main types of chromatophores that create gecko colour:
- Melanophores – contain black/brown melanin pigments
- Xanthophores – contain yellow/red pigments
- Iridophores – reflect blues/greens
Geckos can control these pigment cells and expand or contract them to change their skin colour. For example, expanding melanophores makes the skin appear darker. Iridophores help create brighter blues, greens, and oranges when reflected.
Geckos also have a fourth chromatophore called a guanophore that contains a pigment called guanine. Guanine produces a bright reflective surface and helps reinforce other colour changes. By actively manipulating these chromatophores, geckos can alter their colouration.
When do geckos change colour?
Geckos primarily change colour at the following times:
- When basking to regulate temperature
- When feeling threatened or stressed
- When defending territory from rivals
- When attracting a mate
- When camouflaging against surroundings
Younger geckos also tend to be more vibrantly coloured than mature adults. The ability to rapidly shift colours is especially pronounced in species like crested geckos, day geckos, chameleon geckos, and flat-tailed geckos.
How long does it take?
Geckos are able to change their skin colour relatively quickly. The speed depends on factors like temperature, the type of colour change, and the species of gecko.
Some examples of colour changing speed in different gecko species:
- Moorish Gecko – less than 20 seconds to completely change from brown to green
- Panther Gecko – around 1 minute to darken skin
- Crested Gecko – up to 2 hours to fully darken skin tones
- Leopard Gecko – over 6 hours to change between light and dark phase
As you can see, some species like the Moorish Gecko can change in a matter of seconds. Others, like the Leopard Gecko, may take many hours to fully shift colour. Temperature also plays a key role in speed of colour change.
Do all geckos change colour?
The majority of gecko species have at least some ability to actively change their skin colour. However, there are a few species that do not change colour much at all or simply lack vibrant pigments.
Some gecko species with very limited colour changing ability include:
- Mediterranean House Gecko
- Madagascar Ground Gecko
- Common House Gecko
- Gold Dust Day Gecko
These geckos may be able to lighten or darken a bit, but do not display the dramatic metachrosis seen in most other geckos. They tend to have more solid, fixed colour patterns.
There are also albino strains of typically colourful gecko species that lack any pigment shifting abilities. Albino geckos maintain the same white appearance regardless of temperature or mood.
Are colour changes permanent?
The colour changes exhibited by most geckos are not permanent. They are short-term changes that can reverse once the gecko’s temperature, mood, or surroundings change.
However, some species like the leopard gecko do undergo more long-term, seasonal colour shifts. These reptiles naturally become lighter and more yellow during winter months and darker grey/brown in the summer. But the seasonal changes are not 100% permanent either.
Given their active, quick-changing chromatophores, most colour shifts in geckos are intended to be brief adaptations to temporary conditions, not permanent alterations.
Do geckos change colour at night?
Many nocturnal gecko species do exhibit colour changes at night, typically becoming lighter in tone. Since warmer temperatures stimulate darker pigments, the cooler temperatures of nighttime cause geckos to take on paler hues.
Species like leopard geckos and African fat-tailed geckos often appear much lighter when sleeping at night vs active during the day. However, the colour change is less dramatic than temperature-driven shifts that occur when basking under direct sunlight.
Some primarily diurnal gecko species like day geckos may also dull slightly in colour at night when at rest. But the differences are subtler compared to nocturnal geckos that rely on colours to regulate body heat from the sun.
Can colour changes indicate health issues?
While colour changes in response to environment/temperature are normal, unusual or prolonged colour shifts can potentially indicate health problems in some cases. Here are a few examples:
- Extreme darkening or blackening of skin may signal overheating
- Lethargic geckos may appear washed out or extra pale
- Loss of colour vibrancy may indicate illness, stress or malnutrition
- Spots/discolouration can be sign of skin infection or parasite
If your gecko’s colouration seems abnormal, darkened, extra light, or shows strange blotches/spots, it is a good idea to have them examined by an exotic veterinarian. While some colour variation is normal, drastic changes can mean something is wrong.
Do colours differ between sexes?
There are some subtle differences in colouration between male and female geckos of certain species. These sex-linked colour differences include:
- Male leopard geckos tend to develop more vibrant orange or yellow tones
- Male African fat-tailed geckos usually have more pink or orange on their undersides
- Male crested geckos display more red spots and extensive striping on their backs
However, sex based colour differences only occur in mature adult geckos, not juveniles. And in some gecko species, males and females look exactly alike in colour and patterning.
Sexual maturity and testosterone in males contribute to bolder ornamentation in certain types of geckos. But for most species sex cannot be determined by colour alone. Physical probing is required for accurate sexing.
What causes colour differences between morphs?
There are over 1500 named gecko species, and many have specialized captive-bred colour morphs. The vibrant morphs show wide variation in patterning and colouration.
These morphs are produced through selective breeding to isolate and enhance natural colour mutations. Some common gecko morphs include:
- Albinos – lack all dark pigments due to recessive gene
- Hypomelanistics – reduced black pigment cells
- leucistics- reduced all pigment cells
- Paradox – random patches with little pigment
Breeders combine compatible mutations to create unique designer morphs with bright oranges, yellows, pinks and more. Isolation and amplification of reptile colour mutations allows development of amazing new morphs.
Can temperature influence colour morphs?
While colour morphs are genetic, temperature can still impact the shade intensity. Warmer temperatures tend to result in darker, more saturated colouration in morphs. Cooler temperatures lead to paler, faded tones.
For example, a warm basking spot can help bring out the vibrancy of reds and oranges in a crested gecko flame morph. Proper temperature gradient allows the ideal expression of colour genetics in gecko morphs.
Can stress change a gecko’s colour?
Stress, fear, and anxiety can definitely cause colour changes in geckos. Geckos tend to lighten or darken when stressed, depending on species. Some examples include:
- Crested geckos turn darker grey
- Leopard geckos become paler
- Gargoyle geckos develop darker striping
Rapid colour shifts when handled, moved to a new environment, or sensing predators are indicators of stress. Pay attention to your gecko’s skin tone as it reflects their mood and comfort level.
Do colours fade as geckos age?
It is common for adult geckos to become less colourful as they age. Older geckos often showcase more muted versions of their juvenile colours. Factors like nutrition, temperatures, and genetics influence colour vibrancy over time.
Some common colour changes in aging geckos:
- Washed out version of younger pigments
- Darker overall body colour
- Reduced pattern contrast
- More solid tones vs complex mixes
- Duller versions of juvenile markings
- Less dramatic shifts in colour changes
While these paler and more monotone colourations are normal in mature geckos, extreme fading can indicate illness. Provide proper care and nutrition to help maintain colour vigor into old age.
Can medications influence gecko colour?
Certain medications and supplements can impact gecko skin colour when administered for health issues. Some examples include:
- Calcium supplements increasing colour vibrancy
- Vitamin A helping enhance skin and eye colour
- Antibiotics causing slight darkening of skin
- Antifungal medications leading to temporary skin discolouration
Consult your exotic vet on potential side effects before giving your gecko any supplements or prescribed medicine. Make sure to monitor your gecko’s colouration closely after administering any treatment.
Conclusion
Geckos are amazing reptiles that utilize a variety of colour changing abilities to regulate temperature, hide from predators, communicate, and more. Their special skin cells called chromatophores allow them to swiftly alter colours to adapt to their surroundings and conditions.
Understanding why, when, and how geckos change colour provides critical insight into their biology and behaviour. Next time you notice your gecko shift skin tones, consider what factors might be driving this dazzling ability. With proper care, you can enjoy watching how your gecko’s colours morph and change throughout its long, healthy life.
