Some lizards have the remarkable ability to change their skin color from green to brown and back again. This color change serves as camouflage, helping the lizards blend in with their surroundings and avoid predators. The color change is made possible by specialized pigment cells in the lizard’s skin called chromatophores. In this article, we will explore which species of lizards can change color, how they achieve it, and the benefits it provides.
Chameleons
Chameleons are perhaps the most well-known color changing lizards. Their name is even synonymous with the ability to blend in. There are over 160 species of chameleons, and most have the ability to shift between green, brown, and more colors.
Some notable color changing chameleon species include:
| Common Name | Scientific Name |
|---|---|
| Veiled Chameleon | Chamaeleo calyptratus |
| Panther Chameleon | Furcifer pardalis |
| Jackson’s Chameleon | Trioceros jacksonii |
Chameleons have several different types of specialized color changing cells. Some are structurally arranged to reflect certain wavelengths of light. Others contain pigments like melanin that can be dispersed or aggregated to alter skin tone. Chameleons primarily use color change for camouflage and communication/signaling. The veiled chameleon is particularly adept, able to shift through a wide range of colors in just a few seconds.
Anoles
Anoles are a diverse group of small lizards found throughout the Americas and Caribbean islands. Most anole species can shift between green and brown hues. This ability allows them to blend in among forest vegetation or match the color of tree bark and branches.
Some notable green/brown changing anoles include:
| Common Name | Scientific Name |
|---|---|
| Green Anole | Anolis carolinensis |
| Brown Anole | Anolis sagrei |
| Barbados Anole | Anolis extremus |
Anoles have a single layer of iridophore cells in their skin that reflects blue and green light. To shift from green to brown, melanin pigment cells expand in size, filtering out those wavelengths. This allows more red and orange to be reflected, producing a brownish hue. The color change can occur in just a few minutes, providing effective camouflage.
Bearded Dragons
Bearded dragons are popular pet lizards native to Australia. They are able to alter their colors between light and dark shades. This helps them regulate body temperature and communicate. When cold, a bearded dragon’s skin will appear light gray or white. As they warm up, their coloration shifts to darker black and brown hues.
During mating seasons and displays of aggression, bearded dragons can turn their beards black for signaling. They have specialized pigment cells called melanophores that contain melanin. Dispersing or aggregating the melanin pigment allows them to make rapid color changes.
How Color Change Works
So how exactly are lizards like chameleons and anoles able to shift their skin coloration? As mentioned, the key lies in specialized pigment cells called chromatophores found in the lizard’s dermal layer. There are a few different types:
- Melanophores – Contain dark melanin pigment granules.
- Xanthophores – Contain yellow pigments like carotenoids.
- Iridophores – Reflective plates that produce iridescent blues/greens.
- Erythrophores – Contain red pigments.
These chromatophore cells are able to rapidly expand, contract, disperse, or aggregate their pigment content. This is achieved through the rearrangement of actin filaments in the cells.
Muscle-like cytoskeletal elements allow the cells to grow, move pigments apart, or bunch them together. Signals from the nervous system or hormones initiate these changes. For example, a rise in adrenaline or testosterone can trigger a color shift.
Benefits of Color Changing
The ability to shift skin color provides a number of key benefits for lizards in their environments:
- Camouflage – Blending in helps avoid predators and surprise prey.
- Communication – Visual signals are used to attract mates, warn rivals, and define territories.
- Thermoregulation – Darker colors absorb heat, while lighter hues reflect sunlight.
- Mimicry – Some species mimic the patterning of venomous lizards for defense.
Camouflage is likely the primary evolutionary drive behind color changing abilities. Chameleons, anoles, and other lizards rely heavily on cryptic coloration for protection and hunting.
Rapid color shifts also allow displays of dominance, submission, courtship, and aggression through visual cues. For diurnal lizards, darker skin can help absorb heat in the morning, while reflective lighter tones prevent overheating later in the day.
Other Color Changing Lizards
While chameleons and anoles are well known for shifting between green and brown, other lizard species exhibit color changing abilities too:
- Uta stansburiana (side-blotched lizard) – Brown to green
- Phelsuma madagascariensis (Madagascar day gecko) – Green to red/orange
- Draco volans (flying dragon) – Brown to green
- Cnemaspis psychedelica – Gray to blue/yellow
- Sitana ponticeriana (fan-throated lizard) – Brown to orange
The side-blotched lizard of North America can go from brown to green in just 5-10 seconds to camouflage itself among rocks or vegetation. Male day geckos from Madagascar can switch from green to red/orange as a display of dominance during mating season.
Other species like the psychedelic gecko and fan-throated lizard display wildly unique color shifts that aren’t fully understood but may play a role in camouflage or signaling. As you can see, color changing abilities are diverse and fascinating across different lizard families.
Conclusion
Color changing lizards have mastered the ability to shift their skin tones for camouflage, communication, and thermal regulation. Chameleons and anoles are especially adept, transitioning rapidly between greens and browns. Specialized pigment cells called chromatophores allow them to expand, contract, disperse, or concentrate color pigments. While other lizards have some color shifting abilities, chameleons and anoles exhibit the full range and speed for effective crypsis and signaling in their environments. Their color changing prowess continues to inspire scientists and engineers seeking to replicate such capabilities in artificial systems.